From: butt3rflyh4ck <butterflyhuangxx@gmail.com>
To: Daniel Vetter <daniel@ffwll.ch>
Cc: Rob Clark <robdclark@chromium.org>,
security@kernel.org, Dave Airlie <airlied@linux.ie>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
syzkaller-bugs <syzkaller-bugs@googlegroups.com>,
dri-devel <dri-devel@lists.freedesktop.org>,
"Wilson, Chris" <chris@chris-wilson.co.uk>,
Sean Paul <seanpaul@chromium.org>,
Thomas Zimmermann <tzimmermann@suse.de>,
Sam Ravnborg <sam@ravnborg.org>,
Dan Carpenter <dan.carpenter@oracle.com>,
Emil Velikov <emil.velikov@collabora.com>
Subject: Re: KASAN: use-after-free Read in drm_gem_object_release
Date: Tue, 14 Jul 2020 00:47:15 +0800 [thread overview]
Message-ID: <CAFcO6XMeSL-DfxZPxFiYDD27tvN1Eq79v=-RNV-zaJwhrgzZ3Q@mail.gmail.com> (raw)
In-Reply-To: <CAKMK7uE1idHW4msihsBSbo8aWf602gqT-Z_BCR-gSJCRfugu=w@mail.gmail.com>
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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
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[-- Type: application/octet-stream, Size: 871704 bytes --]
[-- Attachment #3: uaf-drm_gem_object_release.c --]
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// 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;
}
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next prev parent reply other threads:[~2020-07-14 7:04 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-10 8:24 KASAN: use-after-free Read in drm_gem_object_release butt3rflyh4ck
2020-07-10 10:39 ` Greg KH
2020-07-10 11:52 ` Dan Carpenter
2020-07-10 14:01 ` butt3rflyh4ck
2020-07-10 14:03 ` butt3rflyh4ck
2020-07-13 16:12 ` Daniel Vetter
2020-07-13 16:47 ` butt3rflyh4ck [this message]
2020-07-14 7:41 ` Thomas Zimmermann
2020-07-14 8:46 ` Thomas Zimmermann
-- strict thread matches above, loose matches on Subject: below --
2022-07-22 16:23 Dipanjan Das
2022-08-02 19:02 ` Dipanjan Das
2021-05-14 6:42 Dan Bautista
[not found] <00000000000053fea105791276d8@google.com>
2018-10-29 11:51 ` Dmitry Vyukov
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