All of lore.kernel.org
 help / color / mirror / Atom feed
From: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Dmitry Vyukov <dvyukov@google.com>,
	Oleg Nesterov <oleg@redhat.com>,
	Andrea Arcangeli <aarcange@redhat.com>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
	stable@vger.kernel.org
Subject: [PATCHv2 1/2] mm: Fix vma_is_anonymous() false-positives
Date: Thu, 12 Jul 2018 17:56:25 +0300	[thread overview]
Message-ID: <20180712145626.41665-2-kirill.shutemov@linux.intel.com> (raw)
In-Reply-To: <20180712145626.41665-1-kirill.shutemov@linux.intel.com>

vma_is_anonymous() relies on ->vm_ops being NULL to detect anonymous
VMA. This is unreliable as ->mmap may not set ->vm_ops.

False-positive vma_is_anonymous() may lead to crashes:

	next ffff8801ce5e7040 prev ffff8801d20eca50 mm ffff88019c1e13c0
	prot 27 anon_vma ffff88019680cdd8 vm_ops 0000000000000000
	pgoff 0 file ffff8801b2ec2d00 private_data 0000000000000000
	flags: 0xff(read|write|exec|shared|mayread|maywrite|mayexec|mayshare)
	------------[ cut here ]------------
	kernel BUG at mm/memory.c:1422!
	invalid opcode: 0000 [#1] SMP KASAN
	CPU: 0 PID: 18486 Comm: syz-executor3 Not tainted 4.18.0-rc3+ #136
	Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google
	01/01/2011
	RIP: 0010:zap_pmd_range mm/memory.c:1421 [inline]
	RIP: 0010:zap_pud_range mm/memory.c:1466 [inline]
	RIP: 0010:zap_p4d_range mm/memory.c:1487 [inline]
	RIP: 0010:unmap_page_range+0x1c18/0x2220 mm/memory.c:1508
	Code: ff 31 ff 4c 89 e6 42 c6 04 33 f8 e8 92 dd d0 ff 4d 85 e4 0f 85 4a eb ff
	ff e8 54 dc d0 ff 48 8b bd 10 fc ff ff e8 82 95 fe ff <0f> 0b e8 41 dc d0 ff
	0f 0b 4c 89 ad 18 fc ff ff c7 85 7c fb ff ff
	RSP: 0018:ffff8801b0587330 EFLAGS: 00010286
	RAX: 000000000000013c RBX: 1ffff100360b0e9c RCX: ffffc90002620000
	RDX: 0000000000000000 RSI: ffffffff81631851 RDI: 0000000000000001
	RBP: ffff8801b05877c8 R08: ffff880199d40300 R09: ffffed003b5c4fc0
	R10: ffffed003b5c4fc0 R11: ffff8801dae27e07 R12: 0000000000000000
	R13: ffff88019c1e13c0 R14: dffffc0000000000 R15: 0000000020e01000
	FS:  00007fca32251700(0000) GS:ffff8801dae00000(0000) knlGS:0000000000000000
	CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
	CR2: 00007f04c540d000 CR3: 00000001ac1f0000 CR4: 00000000001426f0
	DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
	DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
	Call Trace:
	 unmap_single_vma+0x1a0/0x310 mm/memory.c:1553
	 zap_page_range_single+0x3cc/0x580 mm/memory.c:1644
	 unmap_mapping_range_vma mm/memory.c:2792 [inline]
	 unmap_mapping_range_tree mm/memory.c:2813 [inline]
	 unmap_mapping_pages+0x3a7/0x5b0 mm/memory.c:2845
	 unmap_mapping_range+0x48/0x60 mm/memory.c:2880
	 truncate_pagecache+0x54/0x90 mm/truncate.c:800
	 truncate_setsize+0x70/0xb0 mm/truncate.c:826
	 simple_setattr+0xe9/0x110 fs/libfs.c:409
	 notify_change+0xf13/0x10f0 fs/attr.c:335
	 do_truncate+0x1ac/0x2b0 fs/open.c:63
	 do_sys_ftruncate+0x492/0x560 fs/open.c:205
	 __do_sys_ftruncate fs/open.c:215 [inline]
	 __se_sys_ftruncate fs/open.c:213 [inline]
	 __x64_sys_ftruncate+0x59/0x80 fs/open.c:213
	 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
	 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Reproducer:

	#include <stdio.h>
	#include <stddef.h>
	#include <stdint.h>
	#include <stdlib.h>
	#include <string.h>
	#include <sys/types.h>
	#include <sys/stat.h>
	#include <sys/ioctl.h>
	#include <sys/mman.h>
	#include <unistd.h>
	#include <fcntl.h>

	#define KCOV_INIT_TRACE			_IOR('c', 1, unsigned long)
	#define KCOV_ENABLE			_IO('c', 100)
	#define KCOV_DISABLE			_IO('c', 101)
	#define COVER_SIZE			(1024<<10)

	#define KCOV_TRACE_PC  0
	#define KCOV_TRACE_CMP 1

	int main(int argc, char **argv)
	{
		int fd;
		unsigned long *cover;

		system("mount -t debugfs none /sys/kernel/debug");
		fd = open("/sys/kernel/debug/kcov", O_RDWR);
		ioctl(fd, KCOV_INIT_TRACE, COVER_SIZE);
		cover = mmap(NULL, COVER_SIZE * sizeof(unsigned long),
				PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
		munmap(cover, COVER_SIZE * sizeof(unsigned long));
		cover = mmap(NULL, COVER_SIZE * sizeof(unsigned long),
				PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
		memset(cover, 0, COVER_SIZE * sizeof(unsigned long));
		ftruncate(fd, 3UL << 20);
		return 0;
	}

This can be fixed by assigning anonymous VMAs own vm_ops and not relying
on it being NULL.

If ->mmap() failed to set ->vm_ops, mmap_region() will set it to
dummy_vm_ops. This way we will have non-NULL ->vm_ops for all VMAs.

Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reported-by: syzbot+3f84280d52be9b7083cc@syzkaller.appspotmail.com
Cc: stable@vger.kernel.org
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
---
 arch/ia64/kernel/perfmon.c |  1 +
 arch/ia64/mm/init.c        |  2 ++
 drivers/char/mem.c         |  1 +
 fs/exec.c                  |  1 +
 fs/hugetlbfs/inode.c       |  1 +
 include/linux/mm.h         |  5 ++++-
 mm/khugepaged.c            |  4 ++--
 mm/mmap.c                  | 11 +++++++++++
 mm/nommu.c                 |  9 ++++++++-
 mm/shmem.c                 |  1 +
 mm/util.c                  | 12 ++++++++++++
 11 files changed, 44 insertions(+), 4 deletions(-)

diff --git a/arch/ia64/kernel/perfmon.c b/arch/ia64/kernel/perfmon.c
index 3b38c717008a..13fd6f7d37e8 100644
--- a/arch/ia64/kernel/perfmon.c
+++ b/arch/ia64/kernel/perfmon.c
@@ -2292,6 +2292,7 @@ pfm_smpl_buffer_alloc(struct task_struct *task, struct file *filp, pfm_context_t
 	vma->vm_file	     = get_file(filp);
 	vma->vm_flags	     = VM_READ|VM_MAYREAD|VM_DONTEXPAND|VM_DONTDUMP;
 	vma->vm_page_prot    = PAGE_READONLY; /* XXX may need to change */
+	vma->vm_ops          = &dummy_vm_ops;
 
 	/*
 	 * Now we have everything we need and we can initialize
diff --git a/arch/ia64/mm/init.c b/arch/ia64/mm/init.c
index 18278b448530..f5dfcb723518 100644
--- a/arch/ia64/mm/init.c
+++ b/arch/ia64/mm/init.c
@@ -122,6 +122,7 @@ ia64_init_addr_space (void)
 		vma->vm_end = vma->vm_start + PAGE_SIZE;
 		vma->vm_flags = VM_DATA_DEFAULT_FLAGS|VM_GROWSUP|VM_ACCOUNT;
 		vma->vm_page_prot = vm_get_page_prot(vma->vm_flags);
+		vma->vm_ops = &dummy_vm_ops;
 		down_write(&current->mm->mmap_sem);
 		if (insert_vm_struct(current->mm, vma)) {
 			up_write(&current->mm->mmap_sem);
@@ -141,6 +142,7 @@ ia64_init_addr_space (void)
 			vma->vm_page_prot = __pgprot(pgprot_val(PAGE_READONLY) | _PAGE_MA_NAT);
 			vma->vm_flags = VM_READ | VM_MAYREAD | VM_IO |
 					VM_DONTEXPAND | VM_DONTDUMP;
+			vma->vm_ops = &dummy_vm_ops;
 			down_write(&current->mm->mmap_sem);
 			if (insert_vm_struct(current->mm, vma)) {
 				up_write(&current->mm->mmap_sem);
diff --git a/drivers/char/mem.c b/drivers/char/mem.c
index ffeb60d3434c..f0a8b0b1768b 100644
--- a/drivers/char/mem.c
+++ b/drivers/char/mem.c
@@ -708,6 +708,7 @@ static int mmap_zero(struct file *file, struct vm_area_struct *vma)
 #endif
 	if (vma->vm_flags & VM_SHARED)
 		return shmem_zero_setup(vma);
+	vma->vm_ops = &anon_vm_ops;
 	return 0;
 }
 
diff --git a/fs/exec.c b/fs/exec.c
index 2d4e0075bd24..a1a246062561 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -307,6 +307,7 @@ static int __bprm_mm_init(struct linux_binprm *bprm)
 	 * configured yet.
 	 */
 	BUILD_BUG_ON(VM_STACK_FLAGS & VM_STACK_INCOMPLETE_SETUP);
+	vma->vm_ops = &anon_vm_ops;
 	vma->vm_end = STACK_TOP_MAX;
 	vma->vm_start = vma->vm_end - PAGE_SIZE;
 	vma->vm_flags = VM_SOFTDIRTY | VM_STACK_FLAGS | VM_STACK_INCOMPLETE_SETUP;
diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c
index d508c7844681..5ff73b1398ad 100644
--- a/fs/hugetlbfs/inode.c
+++ b/fs/hugetlbfs/inode.c
@@ -597,6 +597,7 @@ static long hugetlbfs_fallocate(struct file *file, int mode, loff_t offset,
 	memset(&pseudo_vma, 0, sizeof(struct vm_area_struct));
 	pseudo_vma.vm_flags = (VM_HUGETLB | VM_MAYSHARE | VM_SHARED);
 	pseudo_vma.vm_file = file;
+	pseudo_vma.vm_ops = &dummy_vm_ops;
 
 	for (index = start; index < end; index++) {
 		/*
diff --git a/include/linux/mm.h b/include/linux/mm.h
index a0fbb9ffe380..9a35362bbc92 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1536,9 +1536,12 @@ int clear_page_dirty_for_io(struct page *page);
 
 int get_cmdline(struct task_struct *task, char *buffer, int buflen);
 
+extern const struct vm_operations_struct anon_vm_ops;
+extern const struct vm_operations_struct dummy_vm_ops;
+
 static inline bool vma_is_anonymous(struct vm_area_struct *vma)
 {
-	return !vma->vm_ops;
+	return vma->vm_ops == &anon_vm_ops;
 }
 
 #ifdef CONFIG_SHMEM
diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index d7b2a4bf8671..5ae34097aed1 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -440,7 +440,7 @@ int khugepaged_enter_vma_merge(struct vm_area_struct *vma,
 		 * page fault if needed.
 		 */
 		return 0;
-	if (vma->vm_ops || (vm_flags & VM_NO_KHUGEPAGED))
+	if (!vma_is_anonymous(vma) || (vm_flags & VM_NO_KHUGEPAGED))
 		/* khugepaged not yet working on file or special mappings */
 		return 0;
 	hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
@@ -831,7 +831,7 @@ static bool hugepage_vma_check(struct vm_area_struct *vma)
 		return IS_ALIGNED((vma->vm_start >> PAGE_SHIFT) - vma->vm_pgoff,
 				HPAGE_PMD_NR);
 	}
-	if (!vma->anon_vma || vma->vm_ops)
+	if (!vma->anon_vma || !vma_is_anonymous(vma))
 		return false;
 	if (is_vma_temporary_stack(vma))
 		return false;
diff --git a/mm/mmap.c b/mm/mmap.c
index d1eb87ef4b1a..527c17f31635 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -561,6 +561,8 @@ static unsigned long count_vma_pages_range(struct mm_struct *mm,
 void __vma_link_rb(struct mm_struct *mm, struct vm_area_struct *vma,
 		struct rb_node **rb_link, struct rb_node *rb_parent)
 {
+	WARN_ONCE(!vma->vm_ops, "missing vma->vm_ops");
+
 	/* Update tracking information for the gap following the new vma. */
 	if (vma->vm_next)
 		vma_gap_update(vma->vm_next);
@@ -1762,6 +1764,11 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
 		 */
 		vma->vm_file = get_file(file);
 		error = call_mmap(file, vma);
+
+		/* All mappings must have ->vm_ops set */
+		if (!vma->vm_ops)
+			vma->vm_ops = &dummy_vm_ops;
+
 		if (error)
 			goto unmap_and_free_vma;
 
@@ -1780,6 +1787,9 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
 		error = shmem_zero_setup(vma);
 		if (error)
 			goto free_vma;
+	} else {
+		/* vma_is_anonymous() relies on this. */
+		vma->vm_ops = &anon_vm_ops;
 	}
 
 	vma_link(mm, vma, prev, rb_link, rb_parent);
@@ -2999,6 +3009,7 @@ static int do_brk_flags(unsigned long addr, unsigned long request, unsigned long
 
 	INIT_LIST_HEAD(&vma->anon_vma_chain);
 	vma->vm_mm = mm;
+	vma->vm_ops = &anon_vm_ops;
 	vma->vm_start = addr;
 	vma->vm_end = addr + len;
 	vma->vm_pgoff = pgoff;
diff --git a/mm/nommu.c b/mm/nommu.c
index 4452d8bd9ae4..f00f209833ab 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -1058,6 +1058,8 @@ static int do_mmap_shared_file(struct vm_area_struct *vma)
 	int ret;
 
 	ret = call_mmap(vma->vm_file, vma);
+	if (!vma->vm_ops)
+		vma->vm_ops = &dummy_vm_ops;
 	if (ret == 0) {
 		vma->vm_region->vm_top = vma->vm_region->vm_end;
 		return 0;
@@ -1089,6 +1091,8 @@ static int do_mmap_private(struct vm_area_struct *vma,
 	 */
 	if (capabilities & NOMMU_MAP_DIRECT) {
 		ret = call_mmap(vma->vm_file, vma);
+		if (!vma->vm_ops)
+			vma->vm_ops = &dummy_vm_ops;
 		if (ret == 0) {
 			/* shouldn't return success if we're not sharing */
 			BUG_ON(!(vma->vm_flags & VM_MAYSHARE));
@@ -1137,6 +1141,8 @@ static int do_mmap_private(struct vm_area_struct *vma,
 		fpos = vma->vm_pgoff;
 		fpos <<= PAGE_SHIFT;
 
+		vma->vm_ops = &dummy_vm_ops;
+
 		ret = kernel_read(vma->vm_file, base, len, &fpos);
 		if (ret < 0)
 			goto error_free;
@@ -1144,7 +1150,8 @@ static int do_mmap_private(struct vm_area_struct *vma,
 		/* clear the last little bit */
 		if (ret < len)
 			memset(base + ret, 0, len - ret);
-
+	} else {
+		vma->vm_ops = &anon_vm_ops;
 	}
 
 	return 0;
diff --git a/mm/shmem.c b/mm/shmem.c
index 2cab84403055..db5c319161ca 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1424,6 +1424,7 @@ static void shmem_pseudo_vma_init(struct vm_area_struct *vma,
 	/* Bias interleave by inode number to distribute better across nodes */
 	vma->vm_pgoff = index + info->vfs_inode.i_ino;
 	vma->vm_policy = mpol_shared_policy_lookup(&info->policy, index);
+	vma->vm_ops = &dummy_vm_ops;
 }
 
 static void shmem_pseudo_vma_destroy(struct vm_area_struct *vma)
diff --git a/mm/util.c b/mm/util.c
index 3351659200e6..20e6a78f3237 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -20,6 +20,18 @@
 
 #include "internal.h"
 
+/*
+ * All anonymous VMAs have ->vm_ops set to anon_vm_ops.
+ * vma_is_anonymous() reiles on anon_vm_ops to detect anonymous VMA.
+ */
+const struct vm_operations_struct anon_vm_ops = {};
+
+/*
+ * All VMAs have to have ->vm_ops set. dummy_vm_ops can be used if the VMA
+ * doesn't need to handle any of the operations.
+ */
+const struct vm_operations_struct dummy_vm_ops = {};
+
 static inline int is_kernel_rodata(unsigned long addr)
 {
 	return addr >= (unsigned long)__start_rodata &&
-- 
2.18.0


  reply	other threads:[~2018-07-12 14:56 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-07-12 14:56 [PATCHv2 0/2] Fix crash due to vma_is_anonymous() false-positives Kirill A. Shutemov
2018-07-12 14:56 ` Kirill A. Shutemov [this message]
2018-07-12 16:20   ` [PATCHv2 1/2] mm: Fix " Oleg Nesterov
2018-07-12 16:39     ` Kirill A. Shutemov
2018-07-12 14:56 ` [PATCHv2 2/2] mm: Drop unneeded ->vm_ops checks Kirill A. Shutemov
2018-07-16 13:30   ` REGRESSION: " Marcel Ziswiler
2018-07-16 14:20     ` Kirill A. Shutemov
2018-07-16 16:09       ` Marcel Ziswiler
2018-07-16 16:57         ` Kirill A. Shutemov
2018-07-12 15:08 ` [PATCHv2 0/2] Fix crash due to vma_is_anonymous() false-positives Kirill A. Shutemov

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20180712145626.41665-2-kirill.shutemov@linux.intel.com \
    --to=kirill.shutemov@linux.intel.com \
    --cc=aarcange@redhat.com \
    --cc=akpm@linux-foundation.org \
    --cc=dvyukov@google.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=oleg@redhat.com \
    --cc=stable@vger.kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.