KASAN: use-after-free Read in drm_gem_object_release

KASAN: use-after-free Read in drm_gem_object_release

[butt3rflyh4ck]

I report a bug (in linux-5.8.0-rc4) found by syzkaller.

kernel config: https://github.com/butterflyhack/syzkaller-fuzz/blob/master/v5.8.0-rc4.config

I test the reproducer and crash too.

In the drm_em_vram_t() function,  ttm_bo_init() function call
ttm_bo_init_reserved(),
the ttm_bo_init_reserved() function  call ttm_bo_put(), it will free
gbo->bo that is struct ttm_buffer_object.

then, goto the err_drm_gem_object_release lable,
drm_gem_object_release() function will free gbo->bo.base, so cause use
after free.

crash log:
==================================================================
BUG: KASAN: use-after-free in drm_gem_object_release+0xf7/0x120
drivers/gpu/drm/drm_gem.c:953
Read of size 8 at addr ffff888064dfd928 by task syz-executor.2/1320

CPU: 1 PID: 1320 Comm: syz-executor.2 Not tainted 5.8.0-rc4+ #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
1.10.2-1ubuntu1 04/01/2014
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x18f/0x20d lib/dump_stack.c:118
 print_address_description.constprop.0.cold+0xae/0x436 mm/kasan/report.c:383
 __kasan_report mm/kasan/report.c:513 [inline]
 kasan_report.cold+0x1f/0x37 mm/kasan/report.c:530
 drm_gem_object_release+0xf7/0x120 drivers/gpu/drm/drm_gem.c:953
 drm_gem_vram_init drivers/gpu/drm/drm_gem_vram_helper.c:211 [inline]
 drm_gem_vram_create+0x3e6/0x5e0 drivers/gpu/drm/drm_gem_vram_helper.c:244
 drm_gem_vram_fill_create_dumb+0x17a/0x310
drivers/gpu/drm/drm_gem_vram_helper.c:615
 drm_gem_vram_driver_dumb_create+0x51/0xb0
drivers/gpu/drm/drm_gem_vram_helper.c:710
 drm_mode_create_dumb+0x27c/0x300 drivers/gpu/drm/drm_dumb_buffers.c:94
 drm_ioctl_kernel+0x220/0x2e0 drivers/gpu/drm/drm_ioctl.c:787
 drm_ioctl+0x4d2/0x96f drivers/gpu/drm/drm_ioctl.c:887
 vfs_ioctl fs/ioctl.c:48 [inline]
 ksys_ioctl+0x11a/0x180 fs/ioctl.c:753
 __do_sys_ioctl fs/ioctl.c:762 [inline]
 __se_sys_ioctl fs/ioctl.c:760 [inline]
 __x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:760
 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:384
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x467a29
Code: Bad RIP value.
RSP: 002b:00007f98f2d40c48 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 000000000076bf00 RCX: 0000000000467a29
RDX: 0000000020000040 RSI: 00000000c02064b2 RDI: 0000000000000003
RBP: 000000000070c600 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f98f2d416bc
R13: 0000000000000297 R14: 0000000000702040 R15: 00000000004d2418

Allocated by task 1320:
 save_stack+0x1b/0x40 mm/kasan/common.c:48
 set_track mm/kasan/common.c:56 [inline]
 __kasan_kmalloc.constprop.0+0xc2/0xd0 mm/kasan/common.c:494
 kmem_cache_alloc_trace+0x14f/0x2d0 mm/slab.c:3551
 kmalloc include/linux/slab.h:555 [inline]
 kzalloc include/linux/slab.h:669 [inline]
 drm_gem_vram_create+0x425/0x5e0 drivers/gpu/drm/drm_gem_vram_helper.c:239
 drm_gem_vram_fill_create_dumb+0x17a/0x310
drivers/gpu/drm/drm_gem_vram_helper.c:615
 drm_gem_vram_driver_dumb_create+0x51/0xb0
drivers/gpu/drm/drm_gem_vram_helper.c:710
 drm_mode_create_dumb+0x27c/0x300 drivers/gpu/drm/drm_dumb_buffers.c:94
 drm_ioctl_kernel+0x220/0x2e0 drivers/gpu/drm/drm_ioctl.c:787
 drm_ioctl+0x4d2/0x96f drivers/gpu/drm/drm_ioctl.c:887
 vfs_ioctl fs/ioctl.c:48 [inline]
 ksys_ioctl+0x11a/0x180 fs/ioctl.c:753
 __do_sys_ioctl fs/ioctl.c:762 [inline]
 __se_sys_ioctl fs/ioctl.c:760 [inline]
 __x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:760
 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:384
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Freed by task 1320:
 save_stack+0x1b/0x40 mm/kasan/common.c:48
 set_track mm/kasan/common.c:56 [inline]
 kasan_set_free_info mm/kasan/common.c:316 [inline]
 __kasan_slab_free+0xf5/0x140 mm/kasan/common.c:455
 __cache_free mm/slab.c:3426 [inline]
 kfree+0x103/0x2c0 mm/slab.c:3757
 ttm_bo_release+0xae1/0x1350 drivers/gpu/drm/ttm/ttm_bo.c:632
 kref_put include/linux/kref.h:65 [inline]
 ttm_bo_put drivers/gpu/drm/ttm/ttm_bo.c:638 [inline]
 ttm_bo_init_reserved+0xb04/0xd00 drivers/gpu/drm/ttm/ttm_bo.c:1339
 ttm_bo_init+0x10e/0x330 drivers/gpu/drm/ttm/ttm_bo.c:1366
 drm_gem_vram_init drivers/gpu/drm/drm_gem_vram_helper.c:202 [inline]
 drm_gem_vram_create+0x3c1/0x5e0 drivers/gpu/drm/drm_gem_vram_helper.c:244
 drm_gem_vram_fill_create_dumb+0x17a/0x310
drivers/gpu/drm/drm_gem_vram_helper.c:615
 drm_gem_vram_driver_dumb_create+0x51/0xb0
drivers/gpu/drm/drm_gem_vram_helper.c:710
 drm_mode_create_dumb+0x27c/0x300 drivers/gpu/drm/drm_dumb_buffers.c:94
 drm_ioctl_kernel+0x220/0x2e0 drivers/gpu/drm/drm_ioctl.c:787
 drm_ioctl+0x4d2/0x96f drivers/gpu/drm/drm_ioctl.c:887
 vfs_ioctl fs/ioctl.c:48 [inline]
 ksys_ioctl+0x11a/0x180 fs/ioctl.c:753
 __do_sys_ioctl fs/ioctl.c:762 [inline]
 __se_sys_ioctl fs/ioctl.c:760 [inline]
 __x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:760
 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:384
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

The buggy address belongs to the object at ffff888064dfd800
 which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 296 bytes inside of
 1024-byte region [ffff888064dfd800, ffff888064dfdc00)
The buggy address belongs to the page:
page:ffffea0001937f40 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0
flags: 0xfffe0000000200(slab)
raw: 00fffe0000000200 ffffea0000f3c248 ffffea0001ad7388 ffff88806bc00c40
raw: 0000000000000000 ffff888064dfd000 0000000100000002 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888064dfd800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888064dfd880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888064dfd900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                  ^
 ffff888064dfd980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888064dfda00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

Regards,
 butt3rflyh4ck.
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Re: KASAN: use-after-free Read in drm_gem_object_release

[Greg KH]

On Fri, Jul 10, 2020 at 04:24:03PM +0800, butt3rflyh4ck wrote:
> I report a bug (in linux-5.8.0-rc4) found by syzkaller.

Great!

But can you also submit a fix for this as well?  We are drowning in
syzkaller reports and just throwing them at us doesn't really help
anyone here anymore.

thanks,

greg k-h
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Re: KASAN: use-after-free Read in drm_gem_object_release

[Dan Carpenter]

On Fri, Jul 10, 2020 at 04:24:03PM +0800, butt3rflyh4ck wrote:
> I report a bug (in linux-5.8.0-rc4) found by syzkaller.
> 
> kernel config: https://github.com/butterflyhack/syzkaller-fuzz/blob/master/v5.8.0-rc4.config
> 
> I test the reproducer and crash too.
> 
> In the drm_em_vram_t() function,  ttm_bo_init() function call
         ^^^^^^^^^^^^^
This a typo.  The function name is drm_gem_vram_init().

> ttm_bo_init_reserved(),
> the ttm_bo_init_reserved() function  call ttm_bo_put(), it will free
> gbo->bo that is struct ttm_buffer_object.
> 
> then, goto the err_drm_gem_object_release lable,
> drm_gem_object_release() function will free gbo->bo.base, so cause use
> after free.
> 

There is a third free in drm_gem_vram_create().  This is a triple free
bug.  The correct place to free this is in drm_gem_vram_create() because
that's where it was allocated.

This code is quite subtle so I'm not going to attempt to fix it because
I can't test it.

regards,
dan carpenter

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dri-devel mailing list
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Re: KASAN: use-after-free Read in drm_gem_object_release

[butt3rflyh4ck]

[-- Attachment #1: Type: text/plain, Size: 1254 bytes --]

Thank you for pointing out my spelling error. ok, I upload a PoC and
compile it to a binary. you can test it.

regards,
  butt3rflyh4ck.

On Fri, Jul 10, 2020 at 7:53 PM Dan Carpenter <dan.carpenter@oracle.com> wrote:
>
> On Fri, Jul 10, 2020 at 04:24:03PM +0800, butt3rflyh4ck wrote:
> > I report a bug (in linux-5.8.0-rc4) found by syzkaller.
> >
> > kernel config: https://github.com/butterflyhack/syzkaller-fuzz/blob/master/v5.8.0-rc4.config
> >
> > I test the reproducer and crash too.
> >
> > In the drm_em_vram_t() function,  ttm_bo_init() function call
>          ^^^^^^^^^^^^^
> This a typo.  The function name is drm_gem_vram_init().
>
> > ttm_bo_init_reserved(),
> > the ttm_bo_init_reserved() function  call ttm_bo_put(), it will free
> > gbo->bo that is struct ttm_buffer_object.
> >
> > then, goto the err_drm_gem_object_release lable,
> > drm_gem_object_release() function will free gbo->bo.base, so cause use
> > after free.
> >
>
> There is a third free in drm_gem_vram_create().  This is a triple free
> bug.  The correct place to free this is in drm_gem_vram_create() because
> that's where it was allocated.
>
> This code is quite subtle so I'm not going to attempt to fix it because
> I can't test it.
>
> regards,
> dan carpenter
>

[-- Attachment #2: uaf-drm_gem_object_release.c --]
[-- Type: application/octet-stream, Size: 4647 bytes --]

// autogenerated by syzkaller (https://github.com/google/syzkaller)

#define _GNU_SOURCE 

#include <dirent.h>
#include <endian.h>
#include <errno.h>
#include <fcntl.h>
#include <signal.h>
#include <stdarg.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/prctl.h>
#include <sys/stat.h>
#include <sys/syscall.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <time.h>
#include <unistd.h>

static void sleep_ms(uint64_t ms)
{
	usleep(ms * 1000);
}

static uint64_t current_time_ms(void)
{
	struct timespec ts;
	if (clock_gettime(CLOCK_MONOTONIC, &ts))
	exit(1);
	return (uint64_t)ts.tv_sec * 1000 + (uint64_t)ts.tv_nsec / 1000000;
}

static bool write_file(const char* file, const char* what, ...)
{
	char buf[1024];
	va_list args;
	va_start(args, what);
	vsnprintf(buf, sizeof(buf), what, args);
	va_end(args);
	buf[sizeof(buf) - 1] = 0;
	int len = strlen(buf);
	int fd = open(file, O_WRONLY | O_CLOEXEC);
	if (fd == -1)
		return false;
	if (write(fd, buf, len) != len) {
		int err = errno;
		close(fd);
		errno = err;
		return false;
	}
	close(fd);
	return true;
}

static long syz_open_dev(volatile long a0, volatile long a1, volatile long a2)
{
	if (a0 == 0xc || a0 == 0xb) {
		char buf[128];
		sprintf(buf, "/dev/%s/%d:%d", a0 == 0xc ? "char" : "block", (uint8_t)a1, (uint8_t)a2);
		return open(buf, O_RDWR, 0);
	} else {
		char buf[1024];
		char* hash;
strncpy(buf, (char*)a0, sizeof(buf) - 1);
		buf[sizeof(buf) - 1] = 0;
		while ((hash = strchr(buf, '#'))) {
			*hash = '0' + (char)(a1 % 10);
			a1 /= 10;
		}
		return open(buf, a2, 0);
	}
}

static int inject_fault(int nth)
{
	int fd;
	fd = open("/proc/thread-self/fail-nth", O_RDWR);
	if (fd == -1)
	exit(1);
	char buf[16];
	sprintf(buf, "%d", nth + 1);
	if (write(fd, buf, strlen(buf)) != (ssize_t)strlen(buf))
	exit(1);
	return fd;
}

static void kill_and_wait(int pid, int* status)
{
	kill(-pid, SIGKILL);
	kill(pid, SIGKILL);
	int i;
	for (i = 0; i < 100; i++) {
		if (waitpid(-1, status, WNOHANG | __WALL) == pid)
			return;
		usleep(1000);
	}
	DIR* dir = opendir("/sys/fs/fuse/connections");
	if (dir) {
		for (;;) {
			struct dirent* ent = readdir(dir);
			if (!ent)
				break;
			if (strcmp(ent->d_name, ".") == 0 || strcmp(ent->d_name, "..") == 0)
				continue;
			char abort[300];
			snprintf(abort, sizeof(abort), "/sys/fs/fuse/connections/%s/abort", ent->d_name);
			int fd = open(abort, O_WRONLY);
			if (fd == -1) {
				continue;
			}
			if (write(fd, abort, 1) < 0) {
			}
			close(fd);
		}
		closedir(dir);
	} else {
	}
	while (waitpid(-1, status, __WALL) != pid) {
	}
}

static void setup_test()
{
	prctl(PR_SET_PDEATHSIG, SIGKILL, 0, 0, 0);
	setpgrp();
	write_file("/proc/self/oom_score_adj", "1000");
}

static void setup_fault()
{
	static struct {
		const char* file;
		const char* val;
		bool fatal;
	} files[] = {
	    {"/sys/kernel/debug/failslab/ignore-gfp-wait", "N", true},
	    {"/sys/kernel/debug/fail_futex/ignore-private", "N", false},
	    {"/sys/kernel/debug/fail_page_alloc/ignore-gfp-highmem", "N", false},
	    {"/sys/kernel/debug/fail_page_alloc/ignore-gfp-wait", "N", false},
	    {"/sys/kernel/debug/fail_page_alloc/min-order", "0", false},
	};
	unsigned i;
	for (i = 0; i < sizeof(files) / sizeof(files[0]); i++) {
		if (!write_file(files[i].file, files[i].val)) {
			if (files[i].fatal)
	exit(1);
		}
	}
}

static void execute_one(void);

#define WAIT_FLAGS __WALL

static void loop(void)
{
	int iter;
	for (iter = 0;; iter++) {
		int pid = fork();
		if (pid < 0)
	exit(1);
		if (pid == 0) {
			setup_test();
			execute_one();
			exit(0);
		}
		int status = 0;
		uint64_t start = current_time_ms();
		for (;;) {
			if (waitpid(-1, &status, WNOHANG | WAIT_FLAGS) == pid)
				break;
			sleep_ms(1);
			if (current_time_ms() - start < 5 * 1000)
				continue;
			kill_and_wait(pid, &status);
			break;
		}
	}
}

uint64_t r[1] = {0xffffffffffffffff};

void execute_one(void)
{
		intptr_t res = 0;
memcpy((void*)0x200000c0, "/dev/dri/card#\000", 15);
	res = syz_open_dev(0x200000c0, 2, 0);
	if (res != -1)
		r[0] = res;
*(uint32_t*)0x20000040 = 5;
*(uint32_t*)0x20000044 = 0x8000000;
*(uint32_t*)0x20000048 = 2;
*(uint32_t*)0x2000004c = 0;
*(uint32_t*)0x20000050 = 0;
*(uint32_t*)0x20000054 = 0;
*(uint64_t*)0x20000058 = 0;
	inject_fault(8);
	syscall(__NR_ioctl, r[0], 0xc02064b2, 0x20000040ul);

}
int main(void)
{
		syscall(__NR_mmap, 0x1ffff000ul, 0x1000ul, 0ul, 0x32ul, -1, 0ul);
	inject_fault(8);
	syscall(__NR_mmap, 0x20000000ul, 0x1000000ul, 7ul, 0x32ul, -1, 0ul);
	syscall(__NR_mmap, 0x21000000ul, 0x1000ul, 0ul, 0x32ul, -1, 0ul);
	setup_fault();
			loop();
	return 0;
}

[-- Attachment #3: uaf-drm_gem_object_release --]
[-- Type: application/octet-stream, Size: 871704 bytes --]

[-- Attachment #4: Type: text/plain, Size: 160 bytes --]

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Re: KASAN: use-after-free Read in drm_gem_object_release

[butt3rflyh4ck]

[-- Attachment #1: Type: text/plain, Size: 1254 bytes --]

Thank you for pointing out my spelling error. ok, I upload a PoC and
compile it to a binary. you can test it.

regards,
  butt3rflyh4ck.

On Fri, Jul 10, 2020 at 7:53 PM Dan Carpenter <dan.carpenter@oracle.com> wrote:
>
> On Fri, Jul 10, 2020 at 04:24:03PM +0800, butt3rflyh4ck wrote:
> > I report a bug (in linux-5.8.0-rc4) found by syzkaller.
> >
> > kernel config: https://github.com/butterflyhack/syzkaller-fuzz/blob/master/v5.8.0-rc4.config
> >
> > I test the reproducer and crash too.
> >
> > In the drm_em_vram_t() function,  ttm_bo_init() function call
>          ^^^^^^^^^^^^^
> This a typo.  The function name is drm_gem_vram_init().
>
> > ttm_bo_init_reserved(),
> > the ttm_bo_init_reserved() function  call ttm_bo_put(), it will free
> > gbo->bo that is struct ttm_buffer_object.
> >
> > then, goto the err_drm_gem_object_release lable,
> > drm_gem_object_release() function will free gbo->bo.base, so cause use
> > after free.
> >
>
> There is a third free in drm_gem_vram_create().  This is a triple free
> bug.  The correct place to free this is in drm_gem_vram_create() because
> that's where it was allocated.
>
> This code is quite subtle so I'm not going to attempt to fix it because
> I can't test it.
>
> regards,
> dan carpenter
>

[-- Attachment #2: uaf-drm_gem_object_release.c --]
[-- Type: application/octet-stream, Size: 4647 bytes --]

// autogenerated by syzkaller (https://github.com/google/syzkaller)

#define _GNU_SOURCE 

#include <dirent.h>
#include <endian.h>
#include <errno.h>
#include <fcntl.h>
#include <signal.h>
#include <stdarg.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/prctl.h>
#include <sys/stat.h>
#include <sys/syscall.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <time.h>
#include <unistd.h>

static void sleep_ms(uint64_t ms)
{
	usleep(ms * 1000);
}

static uint64_t current_time_ms(void)
{
	struct timespec ts;
	if (clock_gettime(CLOCK_MONOTONIC, &ts))
	exit(1);
	return (uint64_t)ts.tv_sec * 1000 + (uint64_t)ts.tv_nsec / 1000000;
}

static bool write_file(const char* file, const char* what, ...)
{
	char buf[1024];
	va_list args;
	va_start(args, what);
	vsnprintf(buf, sizeof(buf), what, args);
	va_end(args);
	buf[sizeof(buf) - 1] = 0;
	int len = strlen(buf);
	int fd = open(file, O_WRONLY | O_CLOEXEC);
	if (fd == -1)
		return false;
	if (write(fd, buf, len) != len) {
		int err = errno;
		close(fd);
		errno = err;
		return false;
	}
	close(fd);
	return true;
}

static long syz_open_dev(volatile long a0, volatile long a1, volatile long a2)
{
	if (a0 == 0xc || a0 == 0xb) {
		char buf[128];
		sprintf(buf, "/dev/%s/%d:%d", a0 == 0xc ? "char" : "block", (uint8_t)a1, (uint8_t)a2);
		return open(buf, O_RDWR, 0);
	} else {
		char buf[1024];
		char* hash;
strncpy(buf, (char*)a0, sizeof(buf) - 1);
		buf[sizeof(buf) - 1] = 0;
		while ((hash = strchr(buf, '#'))) {
			*hash = '0' + (char)(a1 % 10);
			a1 /= 10;
		}
		return open(buf, a2, 0);
	}
}

static int inject_fault(int nth)
{
	int fd;
	fd = open("/proc/thread-self/fail-nth", O_RDWR);
	if (fd == -1)
	exit(1);
	char buf[16];
	sprintf(buf, "%d", nth + 1);
	if (write(fd, buf, strlen(buf)) != (ssize_t)strlen(buf))
	exit(1);
	return fd;
}

static void kill_and_wait(int pid, int* status)
{
	kill(-pid, SIGKILL);
	kill(pid, SIGKILL);
	int i;
	for (i = 0; i < 100; i++) {
		if (waitpid(-1, status, WNOHANG | __WALL) == pid)
			return;
		usleep(1000);
	}
	DIR* dir = opendir("/sys/fs/fuse/connections");
	if (dir) {
		for (;;) {
			struct dirent* ent = readdir(dir);
			if (!ent)
				break;
			if (strcmp(ent->d_name, ".") == 0 || strcmp(ent->d_name, "..") == 0)
				continue;
			char abort[300];
			snprintf(abort, sizeof(abort), "/sys/fs/fuse/connections/%s/abort", ent->d_name);
			int fd = open(abort, O_WRONLY);
			if (fd == -1) {
				continue;
			}
			if (write(fd, abort, 1) < 0) {
			}
			close(fd);
		}
		closedir(dir);
	} else {
	}
	while (waitpid(-1, status, __WALL) != pid) {
	}
}

static void setup_test()
{
	prctl(PR_SET_PDEATHSIG, SIGKILL, 0, 0, 0);
	setpgrp();
	write_file("/proc/self/oom_score_adj", "1000");
}

static void setup_fault()
{
	static struct {
		const char* file;
		const char* val;
		bool fatal;
	} files[] = {
	    {"/sys/kernel/debug/failslab/ignore-gfp-wait", "N", true},
	    {"/sys/kernel/debug/fail_futex/ignore-private", "N", false},
	    {"/sys/kernel/debug/fail_page_alloc/ignore-gfp-highmem", "N", false},
	    {"/sys/kernel/debug/fail_page_alloc/ignore-gfp-wait", "N", false},
	    {"/sys/kernel/debug/fail_page_alloc/min-order", "0", false},
	};
	unsigned i;
	for (i = 0; i < sizeof(files) / sizeof(files[0]); i++) {
		if (!write_file(files[i].file, files[i].val)) {
			if (files[i].fatal)
	exit(1);
		}
	}
}

static void execute_one(void);

#define WAIT_FLAGS __WALL

static void loop(void)
{
	int iter;
	for (iter = 0;; iter++) {
		int pid = fork();
		if (pid < 0)
	exit(1);
		if (pid == 0) {
			setup_test();
			execute_one();
			exit(0);
		}
		int status = 0;
		uint64_t start = current_time_ms();
		for (;;) {
			if (waitpid(-1, &status, WNOHANG | WAIT_FLAGS) == pid)
				break;
			sleep_ms(1);
			if (current_time_ms() - start < 5 * 1000)
				continue;
			kill_and_wait(pid, &status);
			break;
		}
	}
}

uint64_t r[1] = {0xffffffffffffffff};

void execute_one(void)
{
		intptr_t res = 0;
memcpy((void*)0x200000c0, "/dev/dri/card#\000", 15);
	res = syz_open_dev(0x200000c0, 2, 0);
	if (res != -1)
		r[0] = res;
*(uint32_t*)0x20000040 = 5;
*(uint32_t*)0x20000044 = 0x8000000;
*(uint32_t*)0x20000048 = 2;
*(uint32_t*)0x2000004c = 0;
*(uint32_t*)0x20000050 = 0;
*(uint32_t*)0x20000054 = 0;
*(uint64_t*)0x20000058 = 0;
	inject_fault(8);
	syscall(__NR_ioctl, r[0], 0xc02064b2, 0x20000040ul);

}
int main(void)
{
		syscall(__NR_mmap, 0x1ffff000ul, 0x1000ul, 0ul, 0x32ul, -1, 0ul);
	inject_fault(8);
	syscall(__NR_mmap, 0x20000000ul, 0x1000000ul, 7ul, 0x32ul, -1, 0ul);
	syscall(__NR_mmap, 0x21000000ul, 0x1000ul, 0ul, 0x32ul, -1, 0ul);
	setup_fault();
			loop();
	return 0;
}

[-- Attachment #3: uaf-drm_gem_object_release --]
[-- Type: application/octet-stream, Size: 871704 bytes --]

[-- Attachment #4: Type: text/plain, Size: 160 bytes --]

_______________________________________________
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Re: KASAN: use-after-free Read in drm_gem_object_release

[Daniel Vetter]

Adding Thomas, who's the main author for vram helpers.
-Daniel

On Fri, Jul 10, 2020 at 1:53 PM Dan Carpenter <dan.carpenter@oracle.com> wrote:
>
> On Fri, Jul 10, 2020 at 04:24:03PM +0800, butt3rflyh4ck wrote:
> > I report a bug (in linux-5.8.0-rc4) found by syzkaller.
> >
> > kernel config: https://github.com/butterflyhack/syzkaller-fuzz/blob/master/v5.8.0-rc4.config
> >
> > I test the reproducer and crash too.
> >
> > In the drm_em_vram_t() function,  ttm_bo_init() function call
>          ^^^^^^^^^^^^^
> This a typo.  The function name is drm_gem_vram_init().
>
> > ttm_bo_init_reserved(),
> > the ttm_bo_init_reserved() function  call ttm_bo_put(), it will free
> > gbo->bo that is struct ttm_buffer_object.
> >
> > then, goto the err_drm_gem_object_release lable,
> > drm_gem_object_release() function will free gbo->bo.base, so cause use
> > after free.
> >
>
> There is a third free in drm_gem_vram_create().  This is a triple free
> bug.  The correct place to free this is in drm_gem_vram_create() because
> that's where it was allocated.
>
> This code is quite subtle so I'm not going to attempt to fix it because
> I can't test it.
>
> regards,
> dan carpenter
>


-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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Re: KASAN: use-after-free Read in drm_gem_object_release

[butt3rflyh4ck]

[-- Attachment #1: Type: text/plain, Size: 1589 bytes --]

 Ok, firstly, thank Dan Carpenter for pointing out my spelling error
and I upload a PoC and compile it to a binary, hope that helpful for
you to test it.

regards,
butt3rflyh4ck

On Tue, Jul 14, 2020 at 12:12 AM Daniel Vetter <daniel@ffwll.ch> wrote:
>
> Adding Thomas, who's the main author for vram helpers.
> -Daniel
>
> On Fri, Jul 10, 2020 at 1:53 PM Dan Carpenter <dan.carpenter@oracle.com> wrote:
> >
> > On Fri, Jul 10, 2020 at 04:24:03PM +0800, butt3rflyh4ck wrote:
> > > I report a bug (in linux-5.8.0-rc4) found by syzkaller.
> > >
> > > kernel config: https://github.com/butterflyhack/syzkaller-fuzz/blob/master/v5.8.0-rc4.config
> > >
> > > I test the reproducer and crash too.
> > >
> > > In the drm_em_vram_t() function,  ttm_bo_init() function call
> >          ^^^^^^^^^^^^^
> > This a typo.  The function name is drm_gem_vram_init().
> >
> > > ttm_bo_init_reserved(),
> > > the ttm_bo_init_reserved() function  call ttm_bo_put(), it will free
> > > gbo->bo that is struct ttm_buffer_object.
> > >
> > > then, goto the err_drm_gem_object_release lable,
> > > drm_gem_object_release() function will free gbo->bo.base, so cause use
> > > after free.
> > >
> >
> > There is a third free in drm_gem_vram_create().  This is a triple free
> > bug.  The correct place to free this is in drm_gem_vram_create() because
> > that's where it was allocated.
> >
> > This code is quite subtle so I'm not going to attempt to fix it because
> > I can't test it.
> >
> > regards,
> > dan carpenter
> >
>
>
> --
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch

[-- Attachment #2: uaf-drm_gem_object_release --]
[-- Type: application/octet-stream, Size: 871704 bytes --]

[-- Attachment #3: uaf-drm_gem_object_release.c --]
[-- Type: application/octet-stream, Size: 4647 bytes --]

// autogenerated by syzkaller (https://github.com/google/syzkaller)

#define _GNU_SOURCE 

#include <dirent.h>
#include <endian.h>
#include <errno.h>
#include <fcntl.h>
#include <signal.h>
#include <stdarg.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/prctl.h>
#include <sys/stat.h>
#include <sys/syscall.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <time.h>
#include <unistd.h>

static void sleep_ms(uint64_t ms)
{
	usleep(ms * 1000);
}

static uint64_t current_time_ms(void)
{
	struct timespec ts;
	if (clock_gettime(CLOCK_MONOTONIC, &ts))
	exit(1);
	return (uint64_t)ts.tv_sec * 1000 + (uint64_t)ts.tv_nsec / 1000000;
}

static bool write_file(const char* file, const char* what, ...)
{
	char buf[1024];
	va_list args;
	va_start(args, what);
	vsnprintf(buf, sizeof(buf), what, args);
	va_end(args);
	buf[sizeof(buf) - 1] = 0;
	int len = strlen(buf);
	int fd = open(file, O_WRONLY | O_CLOEXEC);
	if (fd == -1)
		return false;
	if (write(fd, buf, len) != len) {
		int err = errno;
		close(fd);
		errno = err;
		return false;
	}
	close(fd);
	return true;
}

static long syz_open_dev(volatile long a0, volatile long a1, volatile long a2)
{
	if (a0 == 0xc || a0 == 0xb) {
		char buf[128];
		sprintf(buf, "/dev/%s/%d:%d", a0 == 0xc ? "char" : "block", (uint8_t)a1, (uint8_t)a2);
		return open(buf, O_RDWR, 0);
	} else {
		char buf[1024];
		char* hash;
strncpy(buf, (char*)a0, sizeof(buf) - 1);
		buf[sizeof(buf) - 1] = 0;
		while ((hash = strchr(buf, '#'))) {
			*hash = '0' + (char)(a1 % 10);
			a1 /= 10;
		}
		return open(buf, a2, 0);
	}
}

static int inject_fault(int nth)
{
	int fd;
	fd = open("/proc/thread-self/fail-nth", O_RDWR);
	if (fd == -1)
	exit(1);
	char buf[16];
	sprintf(buf, "%d", nth + 1);
	if (write(fd, buf, strlen(buf)) != (ssize_t)strlen(buf))
	exit(1);
	return fd;
}

static void kill_and_wait(int pid, int* status)
{
	kill(-pid, SIGKILL);
	kill(pid, SIGKILL);
	int i;
	for (i = 0; i < 100; i++) {
		if (waitpid(-1, status, WNOHANG | __WALL) == pid)
			return;
		usleep(1000);
	}
	DIR* dir = opendir("/sys/fs/fuse/connections");
	if (dir) {
		for (;;) {
			struct dirent* ent = readdir(dir);
			if (!ent)
				break;
			if (strcmp(ent->d_name, ".") == 0 || strcmp(ent->d_name, "..") == 0)
				continue;
			char abort[300];
			snprintf(abort, sizeof(abort), "/sys/fs/fuse/connections/%s/abort", ent->d_name);
			int fd = open(abort, O_WRONLY);
			if (fd == -1) {
				continue;
			}
			if (write(fd, abort, 1) < 0) {
			}
			close(fd);
		}
		closedir(dir);
	} else {
	}
	while (waitpid(-1, status, __WALL) != pid) {
	}
}

static void setup_test()
{
	prctl(PR_SET_PDEATHSIG, SIGKILL, 0, 0, 0);
	setpgrp();
	write_file("/proc/self/oom_score_adj", "1000");
}

static void setup_fault()
{
	static struct {
		const char* file;
		const char* val;
		bool fatal;
	} files[] = {
	    {"/sys/kernel/debug/failslab/ignore-gfp-wait", "N", true},
	    {"/sys/kernel/debug/fail_futex/ignore-private", "N", false},
	    {"/sys/kernel/debug/fail_page_alloc/ignore-gfp-highmem", "N", false},
	    {"/sys/kernel/debug/fail_page_alloc/ignore-gfp-wait", "N", false},
	    {"/sys/kernel/debug/fail_page_alloc/min-order", "0", false},
	};
	unsigned i;
	for (i = 0; i < sizeof(files) / sizeof(files[0]); i++) {
		if (!write_file(files[i].file, files[i].val)) {
			if (files[i].fatal)
	exit(1);
		}
	}
}

static void execute_one(void);

#define WAIT_FLAGS __WALL

static void loop(void)
{
	int iter;
	for (iter = 0;; iter++) {
		int pid = fork();
		if (pid < 0)
	exit(1);
		if (pid == 0) {
			setup_test();
			execute_one();
			exit(0);
		}
		int status = 0;
		uint64_t start = current_time_ms();
		for (;;) {
			if (waitpid(-1, &status, WNOHANG | WAIT_FLAGS) == pid)
				break;
			sleep_ms(1);
			if (current_time_ms() - start < 5 * 1000)
				continue;
			kill_and_wait(pid, &status);
			break;
		}
	}
}

uint64_t r[1] = {0xffffffffffffffff};

void execute_one(void)
{
		intptr_t res = 0;
memcpy((void*)0x200000c0, "/dev/dri/card#\000", 15);
	res = syz_open_dev(0x200000c0, 2, 0);
	if (res != -1)
		r[0] = res;
*(uint32_t*)0x20000040 = 5;
*(uint32_t*)0x20000044 = 0x8000000;
*(uint32_t*)0x20000048 = 2;
*(uint32_t*)0x2000004c = 0;
*(uint32_t*)0x20000050 = 0;
*(uint32_t*)0x20000054 = 0;
*(uint64_t*)0x20000058 = 0;
	inject_fault(8);
	syscall(__NR_ioctl, r[0], 0xc02064b2, 0x20000040ul);

}
int main(void)
{
		syscall(__NR_mmap, 0x1ffff000ul, 0x1000ul, 0ul, 0x32ul, -1, 0ul);
	inject_fault(8);
	syscall(__NR_mmap, 0x20000000ul, 0x1000000ul, 7ul, 0x32ul, -1, 0ul);
	syscall(__NR_mmap, 0x21000000ul, 0x1000ul, 0ul, 0x32ul, -1, 0ul);
	setup_fault();
			loop();
	return 0;
}

[-- Attachment #4: Type: text/plain, Size: 160 bytes --]

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Re: KASAN: use-after-free Read in drm_gem_object_release

[Thomas Zimmermann]

[-- Attachment #1.1.1: Type: text/plain, Size: 7020 bytes --]

Hi

Am 10.07.20 um 10:24 schrieb butt3rflyh4ck:
> I report a bug (in linux-5.8.0-rc4) found by syzkaller.
> 
> kernel config: https://github.com/butterflyhack/syzkaller-fuzz/blob/master/v5.8.0-rc4.config
> 
> I test the reproducer and crash too.
> 
> In the drm_em_vram_t() function,  ttm_bo_init() function call
> ttm_bo_init_reserved(),
> the ttm_bo_init_reserved() function  call ttm_bo_put(), it will free
> gbo->bo that is struct ttm_buffer_object.
> 
> then, goto the err_drm_gem_object_release lable,
> drm_gem_object_release() function will free gbo->bo.base, so cause use
> after free.

Thanks for reporting. I think we recently had a patch for this problem,
[1] but I asked for some changes. Are you in a position to test a fix?

Best regards
Thomas


[1]
https://lore.kernel.org/dri-devel/20200620062134.82961-1-jiayang5@huawei.com/

> 
> crash log:
> ==================================================================
> BUG: KASAN: use-after-free in drm_gem_object_release+0xf7/0x120
> drivers/gpu/drm/drm_gem.c:953
> Read of size 8 at addr ffff888064dfd928 by task syz-executor.2/1320
> 
> CPU: 1 PID: 1320 Comm: syz-executor.2 Not tainted 5.8.0-rc4+ #1
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
> 1.10.2-1ubuntu1 04/01/2014
> Call Trace:
>  __dump_stack lib/dump_stack.c:77 [inline]
>  dump_stack+0x18f/0x20d lib/dump_stack.c:118
>  print_address_description.constprop.0.cold+0xae/0x436 mm/kasan/report.c:383
>  __kasan_report mm/kasan/report.c:513 [inline]
>  kasan_report.cold+0x1f/0x37 mm/kasan/report.c:530
>  drm_gem_object_release+0xf7/0x120 drivers/gpu/drm/drm_gem.c:953
>  drm_gem_vram_init drivers/gpu/drm/drm_gem_vram_helper.c:211 [inline]
>  drm_gem_vram_create+0x3e6/0x5e0 drivers/gpu/drm/drm_gem_vram_helper.c:244
>  drm_gem_vram_fill_create_dumb+0x17a/0x310
> drivers/gpu/drm/drm_gem_vram_helper.c:615
>  drm_gem_vram_driver_dumb_create+0x51/0xb0
> drivers/gpu/drm/drm_gem_vram_helper.c:710
>  drm_mode_create_dumb+0x27c/0x300 drivers/gpu/drm/drm_dumb_buffers.c:94
>  drm_ioctl_kernel+0x220/0x2e0 drivers/gpu/drm/drm_ioctl.c:787
>  drm_ioctl+0x4d2/0x96f drivers/gpu/drm/drm_ioctl.c:887
>  vfs_ioctl fs/ioctl.c:48 [inline]
>  ksys_ioctl+0x11a/0x180 fs/ioctl.c:753
>  __do_sys_ioctl fs/ioctl.c:762 [inline]
>  __se_sys_ioctl fs/ioctl.c:760 [inline]
>  __x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:760
>  do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:384
>  entry_SYSCALL_64_after_hwframe+0x44/0xa9
> RIP: 0033:0x467a29
> Code: Bad RIP value.
> RSP: 002b:00007f98f2d40c48 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
> RAX: ffffffffffffffda RBX: 000000000076bf00 RCX: 0000000000467a29
> RDX: 0000000020000040 RSI: 00000000c02064b2 RDI: 0000000000000003
> RBP: 000000000070c600 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 00007f98f2d416bc
> R13: 0000000000000297 R14: 0000000000702040 R15: 00000000004d2418
> 
> Allocated by task 1320:
>  save_stack+0x1b/0x40 mm/kasan/common.c:48
>  set_track mm/kasan/common.c:56 [inline]
>  __kasan_kmalloc.constprop.0+0xc2/0xd0 mm/kasan/common.c:494
>  kmem_cache_alloc_trace+0x14f/0x2d0 mm/slab.c:3551
>  kmalloc include/linux/slab.h:555 [inline]
>  kzalloc include/linux/slab.h:669 [inline]
>  drm_gem_vram_create+0x425/0x5e0 drivers/gpu/drm/drm_gem_vram_helper.c:239
>  drm_gem_vram_fill_create_dumb+0x17a/0x310
> drivers/gpu/drm/drm_gem_vram_helper.c:615
>  drm_gem_vram_driver_dumb_create+0x51/0xb0
> drivers/gpu/drm/drm_gem_vram_helper.c:710
>  drm_mode_create_dumb+0x27c/0x300 drivers/gpu/drm/drm_dumb_buffers.c:94
>  drm_ioctl_kernel+0x220/0x2e0 drivers/gpu/drm/drm_ioctl.c:787
>  drm_ioctl+0x4d2/0x96f drivers/gpu/drm/drm_ioctl.c:887
>  vfs_ioctl fs/ioctl.c:48 [inline]
>  ksys_ioctl+0x11a/0x180 fs/ioctl.c:753
>  __do_sys_ioctl fs/ioctl.c:762 [inline]
>  __se_sys_ioctl fs/ioctl.c:760 [inline]
>  __x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:760
>  do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:384
>  entry_SYSCALL_64_after_hwframe+0x44/0xa9
> 
> Freed by task 1320:
>  save_stack+0x1b/0x40 mm/kasan/common.c:48
>  set_track mm/kasan/common.c:56 [inline]
>  kasan_set_free_info mm/kasan/common.c:316 [inline]
>  __kasan_slab_free+0xf5/0x140 mm/kasan/common.c:455
>  __cache_free mm/slab.c:3426 [inline]
>  kfree+0x103/0x2c0 mm/slab.c:3757
>  ttm_bo_release+0xae1/0x1350 drivers/gpu/drm/ttm/ttm_bo.c:632
>  kref_put include/linux/kref.h:65 [inline]
>  ttm_bo_put drivers/gpu/drm/ttm/ttm_bo.c:638 [inline]
>  ttm_bo_init_reserved+0xb04/0xd00 drivers/gpu/drm/ttm/ttm_bo.c:1339
>  ttm_bo_init+0x10e/0x330 drivers/gpu/drm/ttm/ttm_bo.c:1366
>  drm_gem_vram_init drivers/gpu/drm/drm_gem_vram_helper.c:202 [inline]
>  drm_gem_vram_create+0x3c1/0x5e0 drivers/gpu/drm/drm_gem_vram_helper.c:244
>  drm_gem_vram_fill_create_dumb+0x17a/0x310
> drivers/gpu/drm/drm_gem_vram_helper.c:615
>  drm_gem_vram_driver_dumb_create+0x51/0xb0
> drivers/gpu/drm/drm_gem_vram_helper.c:710
>  drm_mode_create_dumb+0x27c/0x300 drivers/gpu/drm/drm_dumb_buffers.c:94
>  drm_ioctl_kernel+0x220/0x2e0 drivers/gpu/drm/drm_ioctl.c:787
>  drm_ioctl+0x4d2/0x96f drivers/gpu/drm/drm_ioctl.c:887
>  vfs_ioctl fs/ioctl.c:48 [inline]
>  ksys_ioctl+0x11a/0x180 fs/ioctl.c:753
>  __do_sys_ioctl fs/ioctl.c:762 [inline]
>  __se_sys_ioctl fs/ioctl.c:760 [inline]
>  __x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:760
>  do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:384
>  entry_SYSCALL_64_after_hwframe+0x44/0xa9
> 
> The buggy address belongs to the object at ffff888064dfd800
>  which belongs to the cache kmalloc-1k of size 1024
> The buggy address is located 296 bytes inside of
>  1024-byte region [ffff888064dfd800, ffff888064dfdc00)
> The buggy address belongs to the page:
> page:ffffea0001937f40 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0
> flags: 0xfffe0000000200(slab)
> raw: 00fffe0000000200 ffffea0000f3c248 ffffea0001ad7388 ffff88806bc00c40
> raw: 0000000000000000 ffff888064dfd000 0000000100000002 0000000000000000
> page dumped because: kasan: bad access detected
> 
> Memory state around the buggy address:
>  ffff888064dfd800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>  ffff888064dfd880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>> ffff888064dfd900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>                                   ^
>  ffff888064dfd980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>  ffff888064dfda00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ==================================================================
> 
> Regards,
>  butt3rflyh4ck.
> _______________________________________________
> dri-devel mailing list
> dri-devel@lists.freedesktop.org
> https://lists.freedesktop.org/mailman/listinfo/dri-devel
> 

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Felix Imendörffer


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_______________________________________________
dri-devel mailing list
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https://lists.freedesktop.org/mailman/listinfo/dri-devel

Re: KASAN: use-after-free Read in drm_gem_object_release

[Thomas Zimmermann]

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Am 14.07.20 um 09:41 schrieb Thomas Zimmermann:
> Hi
> 
> Am 10.07.20 um 10:24 schrieb butt3rflyh4ck:
>> I report a bug (in linux-5.8.0-rc4) found by syzkaller.
>>
>> kernel config: https://github.com/butterflyhack/syzkaller-fuzz/blob/master/v5.8.0-rc4.config
>>
>> I test the reproducer and crash too.
>>
>> In the drm_em_vram_t() function,  ttm_bo_init() function call
>> ttm_bo_init_reserved(),
>> the ttm_bo_init_reserved() function  call ttm_bo_put(), it will free
>> gbo->bo that is struct ttm_buffer_object.
>>
>> then, goto the err_drm_gem_object_release lable,
>> drm_gem_object_release() function will free gbo->bo.base, so cause use
>> after free.
> 
> Thanks for reporting. I think we recently had a patch for this problem,
> [1] but I asked for some changes. Are you in a position to test a fix?
> 
> Best regards
> Thomas
> 
> 
> [1]
> https://lore.kernel.org/dri-devel/20200620062134.82961-1-jiayang5@huawei.com/

I sent out a patchset with this patch and a few additional changes.

https://lore.kernel.org/dri-devel/20200714083238.28479-1-tzimmermann@suse.de/T/#t

Best regards
Thomas

> 
>>
>> crash log:
>> ==================================================================
>> BUG: KASAN: use-after-free in drm_gem_object_release+0xf7/0x120
>> drivers/gpu/drm/drm_gem.c:953
>> Read of size 8 at addr ffff888064dfd928 by task syz-executor.2/1320
>>
>> CPU: 1 PID: 1320 Comm: syz-executor.2 Not tainted 5.8.0-rc4+ #1
>> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
>> 1.10.2-1ubuntu1 04/01/2014
>> Call Trace:
>>  __dump_stack lib/dump_stack.c:77 [inline]
>>  dump_stack+0x18f/0x20d lib/dump_stack.c:118
>>  print_address_description.constprop.0.cold+0xae/0x436 mm/kasan/report.c:383
>>  __kasan_report mm/kasan/report.c:513 [inline]
>>  kasan_report.cold+0x1f/0x37 mm/kasan/report.c:530
>>  drm_gem_object_release+0xf7/0x120 drivers/gpu/drm/drm_gem.c:953
>>  drm_gem_vram_init drivers/gpu/drm/drm_gem_vram_helper.c:211 [inline]
>>  drm_gem_vram_create+0x3e6/0x5e0 drivers/gpu/drm/drm_gem_vram_helper.c:244
>>  drm_gem_vram_fill_create_dumb+0x17a/0x310
>> drivers/gpu/drm/drm_gem_vram_helper.c:615
>>  drm_gem_vram_driver_dumb_create+0x51/0xb0
>> drivers/gpu/drm/drm_gem_vram_helper.c:710
>>  drm_mode_create_dumb+0x27c/0x300 drivers/gpu/drm/drm_dumb_buffers.c:94
>>  drm_ioctl_kernel+0x220/0x2e0 drivers/gpu/drm/drm_ioctl.c:787
>>  drm_ioctl+0x4d2/0x96f drivers/gpu/drm/drm_ioctl.c:887
>>  vfs_ioctl fs/ioctl.c:48 [inline]
>>  ksys_ioctl+0x11a/0x180 fs/ioctl.c:753
>>  __do_sys_ioctl fs/ioctl.c:762 [inline]
>>  __se_sys_ioctl fs/ioctl.c:760 [inline]
>>  __x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:760
>>  do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:384
>>  entry_SYSCALL_64_after_hwframe+0x44/0xa9
>> RIP: 0033:0x467a29
>> Code: Bad RIP value.
>> RSP: 002b:00007f98f2d40c48 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
>> RAX: ffffffffffffffda RBX: 000000000076bf00 RCX: 0000000000467a29
>> RDX: 0000000020000040 RSI: 00000000c02064b2 RDI: 0000000000000003
>> RBP: 000000000070c600 R08: 0000000000000000 R09: 0000000000000000
>> R10: 0000000000000000 R11: 0000000000000246 R12: 00007f98f2d416bc
>> R13: 0000000000000297 R14: 0000000000702040 R15: 00000000004d2418
>>
>> Allocated by task 1320:
>>  save_stack+0x1b/0x40 mm/kasan/common.c:48
>>  set_track mm/kasan/common.c:56 [inline]
>>  __kasan_kmalloc.constprop.0+0xc2/0xd0 mm/kasan/common.c:494
>>  kmem_cache_alloc_trace+0x14f/0x2d0 mm/slab.c:3551
>>  kmalloc include/linux/slab.h:555 [inline]
>>  kzalloc include/linux/slab.h:669 [inline]
>>  drm_gem_vram_create+0x425/0x5e0 drivers/gpu/drm/drm_gem_vram_helper.c:239
>>  drm_gem_vram_fill_create_dumb+0x17a/0x310
>> drivers/gpu/drm/drm_gem_vram_helper.c:615
>>  drm_gem_vram_driver_dumb_create+0x51/0xb0
>> drivers/gpu/drm/drm_gem_vram_helper.c:710
>>  drm_mode_create_dumb+0x27c/0x300 drivers/gpu/drm/drm_dumb_buffers.c:94
>>  drm_ioctl_kernel+0x220/0x2e0 drivers/gpu/drm/drm_ioctl.c:787
>>  drm_ioctl+0x4d2/0x96f drivers/gpu/drm/drm_ioctl.c:887
>>  vfs_ioctl fs/ioctl.c:48 [inline]
>>  ksys_ioctl+0x11a/0x180 fs/ioctl.c:753
>>  __do_sys_ioctl fs/ioctl.c:762 [inline]
>>  __se_sys_ioctl fs/ioctl.c:760 [inline]
>>  __x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:760
>>  do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:384
>>  entry_SYSCALL_64_after_hwframe+0x44/0xa9
>>
>> Freed by task 1320:
>>  save_stack+0x1b/0x40 mm/kasan/common.c:48
>>  set_track mm/kasan/common.c:56 [inline]
>>  kasan_set_free_info mm/kasan/common.c:316 [inline]
>>  __kasan_slab_free+0xf5/0x140 mm/kasan/common.c:455
>>  __cache_free mm/slab.c:3426 [inline]
>>  kfree+0x103/0x2c0 mm/slab.c:3757
>>  ttm_bo_release+0xae1/0x1350 drivers/gpu/drm/ttm/ttm_bo.c:632
>>  kref_put include/linux/kref.h:65 [inline]
>>  ttm_bo_put drivers/gpu/drm/ttm/ttm_bo.c:638 [inline]
>>  ttm_bo_init_reserved+0xb04/0xd00 drivers/gpu/drm/ttm/ttm_bo.c:1339
>>  ttm_bo_init+0x10e/0x330 drivers/gpu/drm/ttm/ttm_bo.c:1366
>>  drm_gem_vram_init drivers/gpu/drm/drm_gem_vram_helper.c:202 [inline]
>>  drm_gem_vram_create+0x3c1/0x5e0 drivers/gpu/drm/drm_gem_vram_helper.c:244
>>  drm_gem_vram_fill_create_dumb+0x17a/0x310
>> drivers/gpu/drm/drm_gem_vram_helper.c:615
>>  drm_gem_vram_driver_dumb_create+0x51/0xb0
>> drivers/gpu/drm/drm_gem_vram_helper.c:710
>>  drm_mode_create_dumb+0x27c/0x300 drivers/gpu/drm/drm_dumb_buffers.c:94
>>  drm_ioctl_kernel+0x220/0x2e0 drivers/gpu/drm/drm_ioctl.c:787
>>  drm_ioctl+0x4d2/0x96f drivers/gpu/drm/drm_ioctl.c:887
>>  vfs_ioctl fs/ioctl.c:48 [inline]
>>  ksys_ioctl+0x11a/0x180 fs/ioctl.c:753
>>  __do_sys_ioctl fs/ioctl.c:762 [inline]
>>  __se_sys_ioctl fs/ioctl.c:760 [inline]
>>  __x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:760
>>  do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:384
>>  entry_SYSCALL_64_after_hwframe+0x44/0xa9
>>
>> The buggy address belongs to the object at ffff888064dfd800
>>  which belongs to the cache kmalloc-1k of size 1024
>> The buggy address is located 296 bytes inside of
>>  1024-byte region [ffff888064dfd800, ffff888064dfdc00)
>> The buggy address belongs to the page:
>> page:ffffea0001937f40 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0
>> flags: 0xfffe0000000200(slab)
>> raw: 00fffe0000000200 ffffea0000f3c248 ffffea0001ad7388 ffff88806bc00c40
>> raw: 0000000000000000 ffff888064dfd000 0000000100000002 0000000000000000
>> page dumped because: kasan: bad access detected
>>
>> Memory state around the buggy address:
>>  ffff888064dfd800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>>  ffff888064dfd880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>>> ffff888064dfd900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>>                                   ^
>>  ffff888064dfd980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>>  ffff888064dfda00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>> ==================================================================
>>
>> Regards,
>>  butt3rflyh4ck.
>> _______________________________________________
>> dri-devel mailing list
>> dri-devel@lists.freedesktop.org
>> https://lists.freedesktop.org/mailman/listinfo/dri-devel
>>
> 

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Felix Imendörffer


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KASAN: use-after-free Read in drm_gem_object_release

[Dipanjan Das]

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Hi,

We would like to report the following bug which has been found by our
modified version of syzkaller.

======================================================
description: KASAN: use-after-free Read in drm_gem_object_release
affected file: drivers/gpu/drm/drm_gem.c
kernel version: 5.4.206
kernel commit: 981f87403bb9841f1e0b7953e12a51f09a47a4f0
git tree: upstream
kernel config: https://syzkaller.appspot.com/text?tag=KernelConfig&x=1aab6d4187ddf667
crash reproducer: attached
======================================================
Crash log:
======================================================
BUG: KASAN: use-after-free in drm_gem_object_release+0xf7/0x120
drivers/gpu/drm/drm_gem.c:952
Read of size 8 at addr ffff888069f2d110 by task syz-executor.2/9649

CPU: 0 PID: 9649 Comm: syz-executor.2 Tainted: G           OE     5.4.206+ #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
1.13.0-1ubuntu1.1 04/01/2014
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1a0/0x217 lib/dump_stack.c:118
 print_address_description.constprop.0.cold+0xd3/0x343 mm/kasan/report.c:374
 __kasan_report.cold+0x75/0x8d mm/kasan/report.c:506
 kasan_report+0x10/0x20 mm/kasan/common.c:645
 drm_gem_object_release+0xf7/0x120 drivers/gpu/drm/drm_gem.c:952
 drm_gem_vram_init drivers/gpu/drm/drm_gem_vram_helper.c:106 [inline]
 drm_gem_vram_create+0x180/0x1f0 drivers/gpu/drm/drm_gem_vram_helper.c:135
 drm_gem_vram_fill_create_dumb+0x13b/0x2c0
drivers/gpu/drm/drm_gem_vram_helper.c:382
 drm_gem_vram_driver_dumb_create+0x5e/0xe0
drivers/gpu/drm/drm_gem_vram_helper.c:509
 drm_mode_create_dumb+0x2a0/0x330 drivers/gpu/drm/drm_dumb_buffers.c:94
 drm_ioctl_kernel+0x21a/0x2e0 drivers/gpu/drm/drm_ioctl.c:787
 drm_ioctl+0x52f/0xa70 drivers/gpu/drm/drm_ioctl.c:890
 vfs_ioctl fs/ioctl.c:47 [inline]
 file_ioctl fs/ioctl.c:510 [inline]
 do_vfs_ioctl+0xd30/0x1340 fs/ioctl.c:697
 ksys_ioctl+0x9b/0xc0 fs/ioctl.c:714
 __do_sys_ioctl fs/ioctl.c:721 [inline]
 __se_sys_ioctl fs/ioctl.c:719 [inline]
 __x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:719
 do_syscall_64+0xf6/0x7b0 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x7f6b40bd24ed
Code: 02 b8 ff ff ff ff c3 66 0f 1f 44 00 00 f3 0f 1e fa 48 89 f8 48
89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d
01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f6b3eb82be8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f6b40cf0f60 RCX: 00007f6b40bd24ed
RDX: 0000000020000180 RSI: 00000000c02064b2 RDI: 0000000000000003
RBP: 00007f6b3eb82c40 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000014
R13: 00007ffc4fb462af R14: 00007f6b40cf0f60 R15: 00007f6b3eb82d80

Allocated by task 9649:
 save_stack+0x1b/0x80 mm/kasan/common.c:71
 set_track mm/kasan/common.c:79 [inline]
 __kasan_kmalloc+0xd2/0xe0 mm/kasan/common.c:521
 kmem_cache_alloc_trace+0x13a/0x4e0 mm/slab.c:3550
 kmalloc include/linux/slab.h:556 [inline]
 kzalloc include/linux/slab.h:690 [inline]
 drm_gem_vram_create+0x53/0x1f0 drivers/gpu/drm/drm_gem_vram_helper.c:131
 drm_gem_vram_fill_create_dumb+0x13b/0x2c0
drivers/gpu/drm/drm_gem_vram_helper.c:382
 drm_gem_vram_driver_dumb_create+0x5e/0xe0
drivers/gpu/drm/drm_gem_vram_helper.c:509
 drm_mode_create_dumb+0x2a0/0x330 drivers/gpu/drm/drm_dumb_buffers.c:94
 drm_ioctl_kernel+0x21a/0x2e0 drivers/gpu/drm/drm_ioctl.c:787
 drm_ioctl+0x52f/0xa70 drivers/gpu/drm/drm_ioctl.c:890
 vfs_ioctl fs/ioctl.c:47 [inline]
 file_ioctl fs/ioctl.c:510 [inline]
 do_vfs_ioctl+0xd30/0x1340 fs/ioctl.c:697
 ksys_ioctl+0x9b/0xc0 fs/ioctl.c:714
 __do_sys_ioctl fs/ioctl.c:721 [inline]
 __se_sys_ioctl fs/ioctl.c:719 [inline]
 __x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:719
 do_syscall_64+0xf6/0x7b0 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 9649:
 save_stack+0x1b/0x80 mm/kasan/common.c:71
 set_track mm/kasan/common.c:79 [inline]
 kasan_set_free_info mm/kasan/common.c:334 [inline]
 __kasan_slab_free+0x103/0x150 mm/kasan/common.c:478
 __cache_free mm/slab.c:3425 [inline]
 kfree+0x10b/0x330 mm/slab.c:3756
 ttm_bo_release_list+0x335/0x4e0 drivers/gpu/drm/ttm/ttm_bo.c:166
 kref_put include/linux/kref.h:65 [inline]
 kref_put include/linux/kref.h:62 [inline]
 ttm_bo_release+0x44c/0xf60 drivers/gpu/drm/ttm/ttm_bo.c:686
 kref_put include/linux/kref.h:65 [inline]
 kref_put include/linux/kref.h:62 [inline]
 ttm_bo_put drivers/gpu/drm/ttm/ttm_bo.c:691 [inline]
 ttm_bo_init_reserved+0x8c1/0x10c0 drivers/gpu/drm/ttm/ttm_bo.c:1390
 ttm_bo_init+0x10e/0x4a0 drivers/gpu/drm/ttm/ttm_bo.c:1419
 drm_gem_vram_init drivers/gpu/drm/drm_gem_vram_helper.c:97 [inline]
 drm_gem_vram_create+0x15c/0x1f0 drivers/gpu/drm/drm_gem_vram_helper.c:135
 drm_gem_vram_fill_create_dumb+0x13b/0x2c0
drivers/gpu/drm/drm_gem_vram_helper.c:382
 drm_gem_vram_driver_dumb_create+0x5e/0xe0
drivers/gpu/drm/drm_gem_vram_helper.c:509
 drm_mode_create_dumb+0x2a0/0x330 drivers/gpu/drm/drm_dumb_buffers.c:94
 drm_ioctl_kernel+0x21a/0x2e0 drivers/gpu/drm/drm_ioctl.c:787
 drm_ioctl+0x52f/0xa70 drivers/gpu/drm/drm_ioctl.c:890
 vfs_ioctl fs/ioctl.c:47 [inline]
 file_ioctl fs/ioctl.c:510 [inline]
 do_vfs_ioctl+0xd30/0x1340 fs/ioctl.c:697
 ksys_ioctl+0x9b/0xc0 fs/ioctl.c:714
 __do_sys_ioctl fs/ioctl.c:721 [inline]
 __se_sys_ioctl fs/ioctl.c:719 [inline]
 __x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:719
 do_syscall_64+0xf6/0x7b0 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff888069f2d000
 which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 272 bytes inside of
 1024-byte region [ffff888069f2d000, ffff888069f2d400)
The buggy address belongs to the page:
page:ffffea0001a7cb40 refcount:1 mapcount:0 mapping:ffff888119400c40 index:0x0
flags: 0xfffe0000000200(slab)
raw: 00fffe0000000200 ffffea0002831748 ffffea00019062c8 ffff888119400c40
raw: 0000000000000000 ffff888069f2d000 0000000100000002 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888069f2d000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888069f2d080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888069f2d100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                         ^
 ffff888069f2d180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888069f2d200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================
==================================================================
BUG: KASAN: double-free or invalid-free in
drm_gem_vram_create+0x1b7/0x1f0
drivers/gpu/drm/drm_gem_vram_helper.c:142

CPU: 0 PID: 9649 Comm: syz-executor.2 Tainted: G    B      OE     5.4.206+ #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
1.13.0-1ubuntu1.1 04/01/2014
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1a0/0x217 lib/dump_stack.c:118
 print_address_description.constprop.0.cold+0xd3/0x343 mm/kasan/report.c:374
 kasan_report_invalid_free+0x61/0xa0 mm/kasan/report.c:468
 __kasan_slab_free+0x135/0x150 mm/kasan/common.c:457
 __cache_free mm/slab.c:3425 [inline]
 kfree+0x10b/0x330 mm/slab.c:3756
 drm_gem_vram_create+0x1b7/0x1f0 drivers/gpu/drm/drm_gem_vram_helper.c:142
 drm_gem_vram_fill_create_dumb+0x13b/0x2c0
drivers/gpu/drm/drm_gem_vram_helper.c:382
 drm_gem_vram_driver_dumb_create+0x5e/0xe0
drivers/gpu/drm/drm_gem_vram_helper.c:509
 drm_mode_create_dumb+0x2a0/0x330 drivers/gpu/drm/drm_dumb_buffers.c:94
 drm_ioctl_kernel+0x21a/0x2e0 drivers/gpu/drm/drm_ioctl.c:787
 drm_ioctl+0x52f/0xa70 drivers/gpu/drm/drm_ioctl.c:890
 vfs_ioctl fs/ioctl.c:47 [inline]
 file_ioctl fs/ioctl.c:510 [inline]
 do_vfs_ioctl+0xd30/0x1340 fs/ioctl.c:697
 ksys_ioctl+0x9b/0xc0 fs/ioctl.c:714
 __do_sys_ioctl fs/ioctl.c:721 [inline]
 __se_sys_ioctl fs/ioctl.c:719 [inline]
 __x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:719
 do_syscall_64+0xf6/0x7b0 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x7f6b40bd24ed
Code: 02 b8 ff ff ff ff c3 66 0f 1f 44 00 00 f3 0f 1e fa 48 89 f8 48
89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d
01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f6b3eb82be8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f6b40cf0f60 RCX: 00007f6b40bd24ed
RDX: 0000000020000180 RSI: 00000000c02064b2 RDI: 0000000000000003
RBP: 00007f6b3eb82c40 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000014
R13: 00007ffc4fb462af R14: 00007f6b40cf0f60 R15: 00007f6b3eb82d80

Allocated by task 9649:
 save_stack+0x1b/0x80 mm/kasan/common.c:71
 set_track mm/kasan/common.c:79 [inline]
 __kasan_kmalloc+0xd2/0xe0 mm/kasan/common.c:521
 kmem_cache_alloc_trace+0x13a/0x4e0 mm/slab.c:3550
 kmalloc include/linux/slab.h:556 [inline]
 kzalloc include/linux/slab.h:690 [inline]
 drm_gem_vram_create+0x53/0x1f0 drivers/gpu/drm/drm_gem_vram_helper.c:131
 drm_gem_vram_fill_create_dumb+0x13b/0x2c0
drivers/gpu/drm/drm_gem_vram_helper.c:382
 drm_gem_vram_driver_dumb_create+0x5e/0xe0
drivers/gpu/drm/drm_gem_vram_helper.c:509
 drm_mode_create_dumb+0x2a0/0x330 drivers/gpu/drm/drm_dumb_buffers.c:94
 drm_ioctl_kernel+0x21a/0x2e0 drivers/gpu/drm/drm_ioctl.c:787
 drm_ioctl+0x52f/0xa70 drivers/gpu/drm/drm_ioctl.c:890
 vfs_ioctl fs/ioctl.c:47 [inline]
 file_ioctl fs/ioctl.c:510 [inline]
 do_vfs_ioctl+0xd30/0x1340 fs/ioctl.c:697
 ksys_ioctl+0x9b/0xc0 fs/ioctl.c:714
 __do_sys_ioctl fs/ioctl.c:721 [inline]
 __se_sys_ioctl fs/ioctl.c:719 [inline]
 __x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:719
 do_syscall_64+0xf6/0x7b0 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 9649:
 save_stack+0x1b/0x80 mm/kasan/common.c:71
 set_track mm/kasan/common.c:79 [inline]
 kasan_set_free_info mm/kasan/common.c:334 [inline]
 __kasan_slab_free+0x103/0x150 mm/kasan/common.c:478
 __cache_free mm/slab.c:3425 [inline]
 kfree+0x10b/0x330 mm/slab.c:3756
 ttm_bo_release_list+0x335/0x4e0 drivers/gpu/drm/ttm/ttm_bo.c:166
 kref_put include/linux/kref.h:65 [inline]
 kref_put include/linux/kref.h:62 [inline]
 ttm_bo_release+0x44c/0xf60 drivers/gpu/drm/ttm/ttm_bo.c:686
 kref_put include/linux/kref.h:65 [inline]
 kref_put include/linux/kref.h:62 [inline]
 ttm_bo_put drivers/gpu/drm/ttm/ttm_bo.c:691 [inline]
 ttm_bo_init_reserved+0x8c1/0x10c0 drivers/gpu/drm/ttm/ttm_bo.c:1390
 ttm_bo_init+0x10e/0x4a0 drivers/gpu/drm/ttm/ttm_bo.c:1419
 drm_gem_vram_init drivers/gpu/drm/drm_gem_vram_helper.c:97 [inline]
 drm_gem_vram_create+0x15c/0x1f0 drivers/gpu/drm/drm_gem_vram_helper.c:135
 drm_gem_vram_fill_create_dumb+0x13b/0x2c0
drivers/gpu/drm/drm_gem_vram_helper.c:382
 drm_gem_vram_driver_dumb_create+0x5e/0xe0
drivers/gpu/drm/drm_gem_vram_helper.c:509
 drm_mode_create_dumb+0x2a0/0x330 drivers/gpu/drm/drm_dumb_buffers.c:94
 drm_ioctl_kernel+0x21a/0x2e0 drivers/gpu/drm/drm_ioctl.c:787
 drm_ioctl+0x52f/0xa70 drivers/gpu/drm/drm_ioctl.c:890
 vfs_ioctl fs/ioctl.c:47 [inline]
 file_ioctl fs/ioctl.c:510 [inline]
 do_vfs_ioctl+0xd30/0x1340 fs/ioctl.c:697
 ksys_ioctl+0x9b/0xc0 fs/ioctl.c:714
 __do_sys_ioctl fs/ioctl.c:721 [inline]
 __se_sys_ioctl fs/ioctl.c:719 [inline]
 __x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:719
 do_syscall_64+0xf6/0x7b0 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff888069f2d000
 which belongs to the cache kmalloc-1k of size 1024
The buggy address is located 0 bytes inside of
 1024-byte region [ffff888069f2d000, ffff888069f2d400)
The buggy address belongs to the page:
page:ffffea0001a7cb40 refcount:1 mapcount:0 mapping:ffff888119400c40 index:0x0
flags: 0xfffe0000000200(slab)
raw: 00fffe0000000200 ffffea0002831748 ffffea00019062c8 ffff888119400c40
raw: 0000000000000000 ffff888069f2d000 0000000100000002 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888069f2cf00: 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc
 ffff888069f2cf80: 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc
>ffff888069f2d000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff888069f2d080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888069f2d100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================

-- 
Thanks and Regards,

Dipanjan

[-- Attachment #2: repro.syz --]
[-- Type: application/octet-stream, Size: 171 bytes --]

r0 = syz_open_dev$dri(&(0x7f0000000540), 0x2000000000000000, 0x0)
ioctl$DRM_IOCTL_MODE_CREATE_DUMB(r0, 0xc02064b2, &(0x7f0000000180)={0x7, 0xfc000, 0xc39}) (fail_nth: 20)

[-- Attachment #3: repro.c --]
[-- Type: text/x-csrc, Size: 5514 bytes --]

// autogenerated by syzkaller (https://github.com/google/syzkaller)

#define _GNU_SOURCE 

#include <endian.h>
#include <errno.h>
#include <fcntl.h>
#include <sched.h>
#include <stdarg.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/mount.h>
#include <sys/prctl.h>
#include <sys/resource.h>
#include <sys/stat.h>
#include <sys/syscall.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>

#include <linux/capability.h>

static bool write_file(const char* file, const char* what, ...)
{
	char buf[1024];
	va_list args;
	va_start(args, what);
	vsnprintf(buf, sizeof(buf), what, args);
	va_end(args);
	buf[sizeof(buf) - 1] = 0;
	int len = strlen(buf);
	int fd = open(file, O_WRONLY | O_CLOEXEC);
	if (fd == -1)
		return false;
	if (write(fd, buf, len) != len) {
		int err = errno;
		close(fd);
		errno = err;
		return false;
	}
	close(fd);
	return true;
}

static long syz_open_dev(volatile long a0, volatile long a1, volatile long a2)
{
	if (a0 == 0xc || a0 == 0xb) {
		char buf[128];
		sprintf(buf, "/dev/%s/%d:%d", a0 == 0xc ? "char" : "block", (uint8_t)a1, (uint8_t)a2);
		return open(buf, O_RDWR, 0);
	} else {
		char buf[1024];
		char* hash;
		strncpy(buf, (char*)a0, sizeof(buf) - 1);
		buf[sizeof(buf) - 1] = 0;
		while ((hash = strchr(buf, '#'))) {
			*hash = '0' + (char)(a1 % 10);
			a1 /= 10;
		}
		return open(buf, a2, 0);
	}
}

static void setup_common()
{
	if (mount(0, "/sys/fs/fuse/connections", "fusectl", 0, 0)) {
	}
}

static void setup_binderfs()
{
	if (mkdir("/dev/binderfs", 0777)) {
	}
	if (mount("binder", "/dev/binderfs", "binder", 0, NULL)) {
	}
	if (symlink("/dev/binderfs", "./binderfs")) {
	}
}

static void loop();

static void sandbox_common()
{
	prctl(PR_SET_PDEATHSIG, SIGKILL, 0, 0, 0);
	setsid();
	struct rlimit rlim;
	rlim.rlim_cur = rlim.rlim_max = (200 << 20);
	setrlimit(RLIMIT_AS, &rlim);
	rlim.rlim_cur = rlim.rlim_max = 32 << 20;
	setrlimit(RLIMIT_MEMLOCK, &rlim);
	rlim.rlim_cur = rlim.rlim_max = 136 << 20;
	setrlimit(RLIMIT_FSIZE, &rlim);
	rlim.rlim_cur = rlim.rlim_max = 1 << 20;
	setrlimit(RLIMIT_STACK, &rlim);
	rlim.rlim_cur = rlim.rlim_max = 0;
	setrlimit(RLIMIT_CORE, &rlim);
	rlim.rlim_cur = rlim.rlim_max = 256;
	setrlimit(RLIMIT_NOFILE, &rlim);
	if (unshare(CLONE_NEWNS)) {
	}
	if (mount(NULL, "/", NULL, MS_REC | MS_PRIVATE, NULL)) {
	}
	if (unshare(CLONE_NEWIPC)) {
	}
	if (unshare(0x02000000)) {
	}
	if (unshare(CLONE_NEWUTS)) {
	}
	if (unshare(CLONE_SYSVSEM)) {
	}
	typedef struct {
		const char* name;
		const char* value;
	} sysctl_t;
	static const sysctl_t sysctls[] = {
		{"/proc/sys/kernel/shmmax", "16777216"},
		{"/proc/sys/kernel/shmall", "536870912"},
		{"/proc/sys/kernel/shmmni", "1024"},
		{"/proc/sys/kernel/msgmax", "8192"},
		{"/proc/sys/kernel/msgmni", "1024"},
		{"/proc/sys/kernel/msgmnb", "1024"},
		{"/proc/sys/kernel/sem", "1024 1048576 500 1024"},
	};
	unsigned i;
	for (i = 0; i < sizeof(sysctls) / sizeof(sysctls[0]); i++)
		write_file(sysctls[i].name, sysctls[i].value);
}

static int wait_for_loop(int pid)
{
	if (pid < 0)
		exit(1);
	int status = 0;
	while (waitpid(-1, &status, __WALL) != pid) {
	}
	return WEXITSTATUS(status);
}

static void drop_caps(void)
{
	struct __user_cap_header_struct cap_hdr = {};
	struct __user_cap_data_struct cap_data[2] = {};
	cap_hdr.version = _LINUX_CAPABILITY_VERSION_3;
	cap_hdr.pid = getpid();
	if (syscall(SYS_capget, &cap_hdr, &cap_data))
		exit(1);
	const int drop = (1 << CAP_SYS_PTRACE) | (1 << CAP_SYS_NICE);
	cap_data[0].effective &= ~drop;
	cap_data[0].permitted &= ~drop;
	cap_data[0].inheritable &= ~drop;
	if (syscall(SYS_capset, &cap_hdr, &cap_data))
		exit(1);
}

static int do_sandbox_none(void)
{
	if (unshare(CLONE_NEWPID)) {
	}
	int pid = fork();
	if (pid != 0)
		return wait_for_loop(pid);
	setup_common();
	sandbox_common();
	drop_caps();
	if (unshare(CLONE_NEWNET)) {
	}
	setup_binderfs();
	loop();
	exit(1);
}

static int inject_fault(int nth)
{
	int fd;
	fd = open("/proc/thread-self/fail-nth", O_RDWR);
	if (fd == -1)
		exit(1);
	char buf[16];
	sprintf(buf, "%d", nth);
	if (write(fd, buf, strlen(buf)) != (ssize_t)strlen(buf))
		exit(1);
	return fd;
}

static void setup_fault()
{
	static struct {
		const char* file;
		const char* val;
		bool fatal;
	} files[] = {
		{"/sys/kernel/debug/failslab/ignore-gfp-wait", "N", true},
		{"/sys/kernel/debug/fail_futex/ignore-private", "N", false},
		{"/sys/kernel/debug/fail_page_alloc/ignore-gfp-highmem", "N", false},
		{"/sys/kernel/debug/fail_page_alloc/ignore-gfp-wait", "N", false},
		{"/sys/kernel/debug/fail_page_alloc/min-order", "0", false},
	};
	unsigned i;
	for (i = 0; i < sizeof(files) / sizeof(files[0]); i++) {
		if (!write_file(files[i].file, files[i].val)) {
			if (files[i].fatal)
				exit(1);
		}
	}
}

uint64_t r[1] = {0xffffffffffffffff};

void loop(void)
{
	intptr_t res = 0;
	memcpy((void*)0x20000540, "/dev/dri/card#\000", 15);
	res = -1;
	res = syz_open_dev(0x20000540, 0x2000000000000000, 0);
	if (res != -1)
		r[0] = res;
	*(uint32_t*)0x20000180 = 7;
	*(uint32_t*)0x20000184 = 0xfc000;
	*(uint32_t*)0x20000188 = 0xc39;
	*(uint32_t*)0x2000018c = 0;
	inject_fault(20);
	syscall(__NR_ioctl, r[0], 0xc02064b2, 0x20000180ul);

}
int main(void)
{
	syscall(__NR_mmap, 0x1ffff000ul, 0x1000ul, 0ul, 0x32ul, -1, 0ul);
	syscall(__NR_mmap, 0x20000000ul, 0x1000000ul, 7ul, 0x32ul, -1, 0ul);
	syscall(__NR_mmap, 0x21000000ul, 0x1000ul, 0ul, 0x32ul, -1, 0ul);
	setup_fault();
	do_sandbox_none();
	return 0;
}

Re: KASAN: use-after-free Read in drm_gem_object_release

[Dipanjan Das]

On Fri, Jul 22, 2022 at 9:23 AM Dipanjan Das
<mail.dipanjan.das@gmail.com> wrote:
> ======================================================
> description: KASAN: use-after-free Read in drm_gem_object_release
> affected file: drivers/gpu/drm/drm_gem.c
> kernel version: 5.4.206
> kernel commit: 981f87403bb9841f1e0b7953e12a51f09a47a4f0
> git tree: upstream
> kernel config: https://syzkaller.appspot.com/text?tag=KernelConfig&x=1aab6d4187ddf667
> crash reproducer: attached
> ======================================================
> Crash log:
> ======================================================
> BUG: KASAN: use-after-free in drm_gem_object_release+0xf7/0x120
> drivers/gpu/drm/drm_gem.c:952
> ==================================================================
> BUG: KASAN: double-free or invalid-free in
> drm_gem_vram_create+0x1b7/0x1f0
> drivers/gpu/drm/drm_gem_vram_helper.c:142

We did an initial analysis for this bug and figured out the following:

If ttm_bo_init_reserved() fails, the `gbo` and `gbo->bo.base` will be
freed by ttm_buffer_object_destroy(). But then drm_gem_vram_create()
and drm_gem_vram_init() will attempt to free `gbo` and `gbo->bo.base`
again. This will result in UAF and Double Free. A similar bug (the
stack traces were a bit different) has been patched by this upstream
commit: https://github.com/torvalds/linux/commit/da62cb7230f0871c30dc9789071f63229158d261.
We applied this patch and can confirm that the repro does not trigger
the issue anymore.

-- 
Thanks and Regards,

Dipanjan

Re: KASAN: use-after-free Read in drm_gem_object_release

[Dan Bautista]

[-- Attachment #1: Type: text/plain, Size: 4 bytes --]

Tse

[-- Attachment #2: Type: text/html, Size: 79 bytes --]

Re: KASAN: use-after-free Read in drm_gem_object_release

[Dmitry Vyukov]

On Thu, Oct 25, 2018 at 9:18 PM, syzbot
<syzbot+e73f2fb5ed5a5df36d33@syzkaller.appspotmail.com> wrote:
> Hello,
>
> syzbot found the following crash on:
>
> HEAD commit:    bd6bf7c10484 Merge tag 'pci-v4.20-changes' of git://git.ke..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=1448a683400000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=2dd8629d56664133
> dashboard link: https://syzkaller.appspot.com/bug?extid=e73f2fb5ed5a5df36d33
> compiler:       gcc (GCC) 8.0.1 20180413 (experimental)
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=11331de5400000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1334e64d400000

+drm maintainers

> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+e73f2fb5ed5a5df36d33@syzkaller.appspotmail.com
>
>  drm_mode_create_dumb+0x28d/0x310 drivers/gpu/drm/drm_dumb_buffers.c:92
>  drm_mode_create_dumb_ioctl+0x25/0x30 drivers/gpu/drm/drm_dumb_buffers.c:98
>  drm_ioctl_kernel+0x245/0x2f0 drivers/gpu/drm/drm_ioctl.c:751
>  drm_ioctl+0x57a/0xb20 drivers/gpu/drm/drm_ioctl.c:847
> ==================================================================
> BUG: KASAN: use-after-free in drm_gem_object_release+0xf1/0x110
> drivers/gpu/drm/drm_gem.c:813
> Read of size 8 at addr ffff8801d83d3410 by task syz-executor977/6742
>
>  vfs_ioctl fs/ioctl.c:46 [inline]
>  file_ioctl fs/ioctl.c:501 [inline]
>  do_vfs_ioctl+0x1de/0x1720 fs/ioctl.c:685
>  ksys_ioctl+0xa9/0xd0 fs/ioctl.c:702
>  __do_sys_ioctl fs/ioctl.c:709 [inline]
>  __se_sys_ioctl fs/ioctl.c:707 [inline]
>  __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:707
>  do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
>  entry_SYSCALL_64_after_hwframe+0x49/0xbe
> RIP: 0033:0x445989
> Code: e8 4c e8 ff ff 48 83 c4 18 c3 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7
> 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff
> 0f 83 6b c8 fb ff c3 66 2e 0f 1f 84 00 00 00 00
> RSP: 002b:00007ffcf076f4e8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
> RAX: ffffffffffffffda RBX: 00007ffcf076f500 RCX: 0000000000445989
> RDX: 0000000020000000 RSI: ffffffffffffffb2 RDI: 0000000000000003
> RBP: 0000000000000004 R08: 0000000000000001 R09: 0000000000000100
> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
> R13: ffffffffffffffff R14: 0000000000000000 R15: 0000000000000000
> CPU: 0 PID: 6742 Comm: syz-executor977 Not tainted 4.19.0+ #80
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> Google 01/01/2011
> Call Trace:
>  __dump_stack lib/dump_stack.c:77 [inline]
>  dump_stack+0x244/0x39d lib/dump_stack.c:113
>  print_address_description.cold.7+0x9/0x1ff mm/kasan/report.c:256
>  kasan_report_error mm/kasan/report.c:354 [inline]
>  kasan_report.cold.8+0x242/0x309 mm/kasan/report.c:412
>  __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433
>  drm_gem_object_release+0xf1/0x110 drivers/gpu/drm/drm_gem.c:813
>  __vgem_gem_destroy drivers/gpu/drm/vgem/vgem_drv.c:175 [inline]
>  vgem_gem_create drivers/gpu/drm/vgem/vgem_drv.c:199 [inline]
>  vgem_gem_dumb_create+0x1f8/0x260 drivers/gpu/drm/vgem/vgem_drv.c:214
>  drm_mode_create_dumb+0x28d/0x310 drivers/gpu/drm/drm_dumb_buffers.c:92
>  drm_mode_create_dumb_ioctl+0x25/0x30 drivers/gpu/drm/drm_dumb_buffers.c:98
>  drm_ioctl_kernel+0x245/0x2f0 drivers/gpu/drm/drm_ioctl.c:751
>  drm_ioctl+0x57a/0xb20 drivers/gpu/drm/drm_ioctl.c:847
>  vfs_ioctl fs/ioctl.c:46 [inline]
>  file_ioctl fs/ioctl.c:501 [inline]
>  do_vfs_ioctl+0x1de/0x1720 fs/ioctl.c:685
>  ksys_ioctl+0xa9/0xd0 fs/ioctl.c:702
>  __do_sys_ioctl fs/ioctl.c:709 [inline]
>  __se_sys_ioctl fs/ioctl.c:707 [inline]
>  __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:707
>  do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
>  entry_SYSCALL_64_after_hwframe+0x49/0xbe
> RIP: 0033:0x445989
> Code: e8 4c e8 ff ff 48 83 c4 18 c3 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7
> 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff
> 0f 83 6b c8 fb ff c3 66 2e 0f 1f 84 00 00 00 00
> RSP: 002b:00007ffcf076f4e8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
> RAX: ffffffffffffffda RBX: 00007ffcf076f500 RCX: 0000000000445989
> RDX: 0000000020000000 RSI: ffffffffffffffb2 RDI: 0000000000000003
> RBP: 0000000000000004 R08: 0000000000000001 R09: 0000000000000100
> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
> R13: ffffffffffffffff R14: 0000000000000000 R15: 0000000000000000
>
> Allocated by task 6742:
>  save_stack+0x43/0xd0 mm/kasan/kasan.c:448
>  set_track mm/kasan/kasan.c:460 [inline]
>  kasan_kmalloc+0xc7/0xe0 mm/kasan/kasan.c:553
>  kmem_cache_alloc_trace+0x152/0x750 mm/slab.c:3620
>  kmalloc include/linux/slab.h:513 [inline]
>  kzalloc include/linux/slab.h:707 [inline]
>  __vgem_gem_create+0x4c/0x100 drivers/gpu/drm/vgem/vgem_drv.c:158
>  vgem_gem_create drivers/gpu/drm/vgem/vgem_drv.c:187 [inline]
>  vgem_gem_dumb_create+0xce/0x260 drivers/gpu/drm/vgem/vgem_drv.c:214
>  drm_mode_create_dumb+0x28d/0x310 drivers/gpu/drm/drm_dumb_buffers.c:92
>  drm_mode_create_dumb_ioctl+0x25/0x30 drivers/gpu/drm/drm_dumb_buffers.c:98
>  drm_ioctl_kernel+0x245/0x2f0 drivers/gpu/drm/drm_ioctl.c:751
>  drm_ioctl+0x57a/0xb20 drivers/gpu/drm/drm_ioctl.c:847
>  vfs_ioctl fs/ioctl.c:46 [inline]
>  file_ioctl fs/ioctl.c:501 [inline]
>  do_vfs_ioctl+0x1de/0x1720 fs/ioctl.c:685
>  ksys_ioctl+0xa9/0xd0 fs/ioctl.c:702
>  __do_sys_ioctl fs/ioctl.c:709 [inline]
>  __se_sys_ioctl fs/ioctl.c:707 [inline]
>  __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:707
>  do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
>  entry_SYSCALL_64_after_hwframe+0x49/0xbe
>
> Freed by task 6742:
>  save_stack+0x43/0xd0 mm/kasan/kasan.c:448
>  set_track mm/kasan/kasan.c:460 [inline]
>  __kasan_slab_free+0x102/0x150 mm/kasan/kasan.c:521
>  kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528
>  __cache_free mm/slab.c:3498 [inline]
>  kfree+0xcf/0x230 mm/slab.c:3813
>  vgem_gem_free_object+0xb6/0xe0 drivers/gpu/drm/vgem/vgem_drv.c:61
>  drm_gem_object_free+0xf1/0x2b0 drivers/gpu/drm/drm_gem.c:839
>  kref_put include/linux/kref.h:70 [inline]
>  drm_gem_object_put_unlocked+0x14c/0x180 drivers/gpu/drm/drm_gem.c:895
>  vgem_gem_create drivers/gpu/drm/vgem/vgem_drv.c:192 [inline]
>  vgem_gem_dumb_create+0x120/0x260 drivers/gpu/drm/vgem/vgem_drv.c:214
>  drm_mode_create_dumb+0x28d/0x310 drivers/gpu/drm/drm_dumb_buffers.c:92
>  drm_mode_create_dumb_ioctl+0x25/0x30 drivers/gpu/drm/drm_dumb_buffers.c:98
>  drm_ioctl_kernel+0x245/0x2f0 drivers/gpu/drm/drm_ioctl.c:751
>  drm_ioctl+0x57a/0xb20 drivers/gpu/drm/drm_ioctl.c:847
>  vfs_ioctl fs/ioctl.c:46 [inline]
>  file_ioctl fs/ioctl.c:501 [inline]
>  do_vfs_ioctl+0x1de/0x1720 fs/ioctl.c:685
>  ksys_ioctl+0xa9/0xd0 fs/ioctl.c:702
>  __do_sys_ioctl fs/ioctl.c:709 [inline]
>  __se_sys_ioctl fs/ioctl.c:707 [inline]
>  __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:707
>  do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
>  entry_SYSCALL_64_after_hwframe+0x49/0xbe
>
> The buggy address belongs to the object at ffff8801d83d3300
>  which belongs to the cache kmalloc-512 of size 512
> The buggy address is located 272 bytes inside of
>  512-byte region [ffff8801d83d3300, ffff8801d83d3500)
> The buggy address belongs to the page:
> page:ffffea000760f4c0 count:1 mapcount:0 mapping:ffff8801da800940 index:0x0
> flags: 0x2fffc0000000100(slab)
> raw: 02fffc0000000100 ffffea0007473948 ffffea0007471dc8 ffff8801da800940
> raw: 0000000000000000 ffff8801d83d3080 0000000100000006 0000000000000000
> page dumped because: kasan: bad access detected
>
> Memory state around the buggy address:
>  ffff8801d83d3300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>  ffff8801d83d3380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>>
>> ffff8801d83d3400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>
>                          ^
>  ffff8801d83d3480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>  ffff8801d83d3500: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> ==================================================================
> ==================================================================
> CPU: 0 PID: 6778 Comm: syz-executor977 Tainted: G    B             4.19.0+
> #80
> BUG: KASAN: double-free or invalid-free in __vgem_gem_destroy
> drivers/gpu/drm/vgem/vgem_drv.c:176 [inline]
> BUG: KASAN: double-free or invalid-free in vgem_gem_create
> drivers/gpu/drm/vgem/vgem_drv.c:199 [inline]
> BUG: KASAN: double-free or invalid-free in vgem_gem_dumb_create+0x203/0x260
> drivers/gpu/drm/vgem/vgem_drv.c:214
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> Google 01/01/2011
>
> Call Trace:
>  __dump_stack lib/dump_stack.c:77 [inline]
>  dump_stack+0x244/0x39d lib/dump_stack.c:113
>  fail_dump lib/fault-inject.c:51 [inline]
>  should_fail.cold.4+0xa/0x17 lib/fault-inject.c:149
>  __should_failslab+0x124/0x180 mm/failslab.c:32
>  should_failslab+0x9/0x14 mm/slab_common.c:1557
>  slab_pre_alloc_hook mm/slab.h:423 [inline]
>  slab_alloc mm/slab.c:3378 [inline]
>  kmem_cache_alloc_trace+0x2d7/0x750 mm/slab.c:3618
>  kmalloc include/linux/slab.h:513 [inline]
>  drm_vma_node_allow+0x5f/0x290 drivers/gpu/drm/drm_vma_manager.c:277
>  drm_gem_handle_create_tail+0x233/0x440 drivers/gpu/drm/drm_gem.c:409
>  drm_gem_handle_create+0x52/0x60 drivers/gpu/drm/drm_gem.c:452
>  vgem_gem_create drivers/gpu/drm/vgem/vgem_drv.c:191 [inline]
>  vgem_gem_dumb_create+0x115/0x260 drivers/gpu/drm/vgem/vgem_drv.c:214
>  drm_mode_create_dumb+0x28d/0x310 drivers/gpu/drm/drm_dumb_buffers.c:92
>  drm_mode_create_dumb_ioctl+0x25/0x30 drivers/gpu/drm/drm_dumb_buffers.c:98
>  drm_ioctl_kernel+0x245/0x2f0 drivers/gpu/drm/drm_ioctl.c:751
>  drm_ioctl+0x57a/0xb20 drivers/gpu/drm/drm_ioctl.c:847
>  vfs_ioctl fs/ioctl.c:46 [inline]
>  file_ioctl fs/ioctl.c:501 [inline]
>  do_vfs_ioctl+0x1de/0x1720 fs/ioctl.c:685
>  ksys_ioctl+0xa9/0xd0 fs/ioctl.c:702
>  __do_sys_ioctl fs/ioctl.c:709 [inline]
>  __se_sys_ioctl fs/ioctl.c:707 [inline]
>  __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:707
>  do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
>  entry_SYSCALL_64_after_hwframe+0x49/0xbe
> RIP: 0033:0x445989
> Code: e8 4c e8 ff ff 48 83 c4 18 c3 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7
> 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff
> 0f 83 6b c8 fb ff c3 66 2e 0f 1f 84 00 00 00 00
> RSP: 002b:00007ffcf076f4e8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
> RAX: ffffffffffffffda RBX: 00007ffcf076f500 RCX: 0000000000445989
> RDX: 0000000020000000 RSI: ffffffffffffffb2 RDI: 0000000000000003
> RBP: 0000000000000004 R08: 0000000000000001 R09: 0000000000000100
> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
> R13: ffffffffffffffff R14: 0000000000000000 R15: 0000000000000000
> CPU: 1 PID: 6767 Comm: syz-executor977 Tainted: G    B             4.19.0+
> #80
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> Google 01/01/2011
> Call Trace:
>  __dump_stack lib/dump_stack.c:77 [inline]
>  dump_stack+0x244/0x39d lib/dump_stack.c:113
>  print_address_description.cold.7+0x9/0x1ff mm/kasan/report.c:256
>  kasan_report_invalid_free+0x64/0xa0 mm/kasan/report.c:336
>  __kasan_slab_free+0x13a/0x150 mm/kasan/kasan.c:501
>  kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528
>  __cache_free mm/slab.c:3498 [inline]
>  kfree+0xcf/0x230 mm/slab.c:3813
>  __vgem_gem_destroy drivers/gpu/drm/vgem/vgem_drv.c:176 [inline]
>  vgem_gem_create drivers/gpu/drm/vgem/vgem_drv.c:199 [inline]
>  vgem_gem_dumb_create+0x203/0x260 drivers/gpu/drm/vgem/vgem_drv.c:214
>  drm_mode_create_dumb+0x28d/0x310 drivers/gpu/drm/drm_dumb_buffers.c:92
>  drm_mode_create_dumb_ioctl+0x25/0x30 drivers/gpu/drm/drm_dumb_buffers.c:98
>  drm_ioctl_kernel+0x245/0x2f0 drivers/gpu/drm/drm_ioctl.c:751
>  drm_ioctl+0x57a/0xb20 drivers/gpu/drm/drm_ioctl.c:847
>  vfs_ioctl fs/ioctl.c:46 [inline]
>  file_ioctl fs/ioctl.c:501 [inline]
>  do_vfs_ioctl+0x1de/0x1720 fs/ioctl.c:685
>  ksys_ioctl+0xa9/0xd0 fs/ioctl.c:702
>  __do_sys_ioctl fs/ioctl.c:709 [inline]
>  __se_sys_ioctl fs/ioctl.c:707 [inline]
>  __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:707
>  do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
>  entry_SYSCALL_64_after_hwframe+0x49/0xbe
> RIP: 0033:0x445989
> Code: e8 4c e8 ff ff 48 83 c4 18 c3 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7
> 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff
> 0f 83 6b c8 fb ff c3 66 2e 0f 1f 84 00 00 00 00
> RSP: 002b:00007ffcf076f4e8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
> RAX: ffffffffffffffda RBX: 00007ffcf076f500 RCX: 0000000000445989
> RDX: 0000000020000000 RSI: ffffffffffffffb2 RDI: 0000000000000003
> RBP: 0000000000000004 R08: 0000000000000001 R09: 0000000000000100
> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
> R13: ffffffffffffffff R14: 0000000000000000 R15: 0000000000000000
>
> Allocated by task 6767:
>  save_stack+0x43/0xd0 mm/kasan/kasan.c:448
>  set_track mm/kasan/kasan.c:460 [inline]
>  kasan_kmalloc+0xc7/0xe0 mm/kasan/kasan.c:553
>  kmem_cache_alloc_trace+0x152/0x750 mm/slab.c:3620
>  kmalloc include/linux/slab.h:513 [inline]
>  kzalloc include/linux/slab.h:707 [inline]
>  __vgem_gem_create+0x4c/0x100 drivers/gpu/drm/vgem/vgem_drv.c:158
>  vgem_gem_create drivers/gpu/drm/vgem/vgem_drv.c:187 [inline]
>  vgem_gem_dumb_create+0xce/0x260 drivers/gpu/drm/vgem/vgem_drv.c:214
>  drm_mode_create_dumb+0x28d/0x310 drivers/gpu/drm/drm_dumb_buffers.c:92
>  drm_mode_create_dumb_ioctl+0x25/0x30 drivers/gpu/drm/drm_dumb_buffers.c:98
>  drm_ioctl_kernel+0x245/0x2f0 drivers/gpu/drm/drm_ioctl.c:751
>  drm_ioctl+0x57a/0xb20 drivers/gpu/drm/drm_ioctl.c:847
>  vfs_ioctl fs/ioctl.c:46 [inline]
>  file_ioctl fs/ioctl.c:501 [inline]
>  do_vfs_ioctl+0x1de/0x1720 fs/ioctl.c:685
>  ksys_ioctl+0xa9/0xd0 fs/ioctl.c:702
>  __do_sys_ioctl fs/ioctl.c:709 [inline]
>  __se_sys_ioctl fs/ioctl.c:707 [inline]
>  __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:707
>  do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
>  entry_SYSCALL_64_after_hwframe+0x49/0xbe
>
> Freed by task 6767:
>  save_stack+0x43/0xd0 mm/kasan/kasan.c:448
>  set_track mm/kasan/kasan.c:460 [inline]
>  __kasan_slab_free+0x102/0x150 mm/kasan/kasan.c:521
>  kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528
>  __cache_free mm/slab.c:3498 [inline]
>  kfree+0xcf/0x230 mm/slab.c:3813
>  vgem_gem_free_object+0xb6/0xe0 drivers/gpu/drm/vgem/vgem_drv.c:61
>  drm_gem_object_free+0xf1/0x2b0 drivers/gpu/drm/drm_gem.c:839
>  kref_put include/linux/kref.h:70 [inline]
>  drm_gem_object_put_unlocked+0x14c/0x180 drivers/gpu/drm/drm_gem.c:895
>  vgem_gem_create drivers/gpu/drm/vgem/vgem_drv.c:192 [inline]
>  vgem_gem_dumb_create+0x120/0x260 drivers/gpu/drm/vgem/vgem_drv.c:214
>  drm_mode_create_dumb+0x28d/0x310 drivers/gpu/drm/drm_dumb_buffers.c:92
>  drm_mode_create_dumb_ioctl+0x25/0x30 drivers/gpu/drm/drm_dumb_buffers.c:98
>  drm_ioctl_kernel+0x245/0x2f0 drivers/gpu/drm/drm_ioctl.c:751
>  drm_ioctl+0x57a/0xb20 drivers/gpu/drm/drm_ioctl.c:847
>  vfs_ioctl fs/ioctl.c:46 [inline]
>  file_ioctl fs/ioctl.c:501 [inline]
>  do_vfs_ioctl+0x1de/0x1720 fs/ioctl.c:685
>  ksys_ioctl+0xa9/0xd0 fs/ioctl.c:702
>  __do_sys_ioctl fs/ioctl.c:709 [inline]
>  __se_sys_ioctl fs/ioctl.c:707 [inline]
>  __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:707
>  do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
>  entry_SYSCALL_64_after_hwframe+0x49/0xbe
>
> The buggy address belongs to the object at ffff8801d4974080
>  which belongs to the cache kmalloc-512 of size 512
> The buggy address is located 0 bytes inside of
>  512-byte region [ffff8801d4974080, ffff8801d4974280)
> The buggy address belongs to the page:
> page:ffffea0007525d00 count:1 mapcount:0 mapping:ffff8801da800940 index:0x0
> flags: 0x2fffc0000000100(slab)
> raw: 02fffc0000000100 ffffea0007558e48 ffffea00071d0508 ffff8801da800940
> raw: 0000000000000000 ffff8801d4974080 0000000100000006 0000000000000000
> page dumped because: kasan: bad access detected
>
> Memory state around the buggy address:
>  ffff8801d4973f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>  ffff8801d4974000: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>>
>> ffff8801d4974080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>
>                    ^
>  ffff8801d4974100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>  ffff8801d4974180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
> ==================================================================
> ==================================================================
>
>
> ---
> This bug is generated by a bot. It may contain errors.
> See https://goo.gl/tpsmEJ for more information about syzbot.
> syzbot engineers can be reached at syzkaller@googlegroups.com.
>
> syzbot will keep track of this bug report. See:
> https://goo.gl/tpsmEJ#bug-status-tracking for how to communicate with
> syzbot.
> syzbot can test patches for this bug, for details see:
> https://goo.gl/tpsmEJ#testing-patches
>
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