From: Chao Yu chao@kernel.org
[ Upstream commit eb70d5a6c932d9d23f4bb3e7b83782c21ac4b064 ]
syzbot reports a f2fs bug as below:
BUG: KASAN: slab-use-after-free in f2fs_filemap_fault+0xd1/0x2c0 fs/f2fs/file.c:49 Read of size 8 at addr ffff88807bb22680 by task syz-executor184/5058
CPU: 0 PID: 5058 Comm: syz-executor184 Not tainted 6.7.0-syzkaller-09928-g052d534373b7 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/17/2023 Call Trace: <TASK> __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x1e7/0x2d0 lib/dump_stack.c:106 print_address_description mm/kasan/report.c:377 [inline] print_report+0x163/0x540 mm/kasan/report.c:488 kasan_report+0x142/0x170 mm/kasan/report.c:601 f2fs_filemap_fault+0xd1/0x2c0 fs/f2fs/file.c:49 __do_fault+0x131/0x450 mm/memory.c:4376 do_shared_fault mm/memory.c:4798 [inline] do_fault mm/memory.c:4872 [inline] do_pte_missing mm/memory.c:3745 [inline] handle_pte_fault mm/memory.c:5144 [inline] __handle_mm_fault+0x23b7/0x72b0 mm/memory.c:5285 handle_mm_fault+0x27e/0x770 mm/memory.c:5450 do_user_addr_fault arch/x86/mm/fault.c:1364 [inline] handle_page_fault arch/x86/mm/fault.c:1507 [inline] exc_page_fault+0x456/0x870 arch/x86/mm/fault.c:1563 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:570
The root cause is: in f2fs_filemap_fault(), vmf->vma may be not alive after filemap_fault(), so it may cause use-after-free issue when accessing vmf->vma->vm_flags in trace_f2fs_filemap_fault(). So it needs to keep vm_flags in separated temporary variable for tracepoint use.
Fixes: 87f3afd366f7 ("f2fs: add tracepoint for f2fs_vm_page_mkwrite()") Reported-and-tested-by: syzbot+763afad57075d3f862f2@syzkaller.appspotmail.com Closes: https://lore.kernel.org/lkml/000000000000e8222b060f00db3b@google.com Cc: Ed Tsai Ed.Tsai@mediatek.com Suggested-by: Hillf Danton hdanton@sina.com Signed-off-by: Chao Yu chao@kernel.org Signed-off-by: Jaegeuk Kim jaegeuk@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- fs/f2fs/file.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c index ffe7fca39a8e8..51970b345eeee 100644 --- a/fs/f2fs/file.c +++ b/fs/f2fs/file.c @@ -39,6 +39,7 @@ static vm_fault_t f2fs_filemap_fault(struct vm_fault *vmf) { struct inode *inode = file_inode(vmf->vma->vm_file); + vm_flags_t flags = vmf->vma->vm_flags; vm_fault_t ret;
ret = filemap_fault(vmf); @@ -46,7 +47,7 @@ static vm_fault_t f2fs_filemap_fault(struct vm_fault *vmf) f2fs_update_iostat(F2FS_I_SB(inode), inode, APP_MAPPED_READ_IO, F2FS_BLKSIZE);
- trace_f2fs_filemap_fault(inode, vmf->pgoff, vmf->vma->vm_flags, ret); + trace_f2fs_filemap_fault(inode, vmf->pgoff, flags, ret);
return ret; }