On Wed, Oct 25, 2023 at 08:54:32AM +0000, Kazunori Kobayashi wrote:
From: Chao Yu chao@kernel.org
commit 9056d6489f5a41cfbb67f719d2c0ce61ead72d9f upstream.
As report by Wenqing Liu in bugzilla:
https://bugzilla.kernel.org/show_bug.cgi?id=215231
- Overview
kernel NULL pointer dereference triggered in folio_mark_dirty() when mount and operate on a crafted f2fs image
- Reproduce
tested on kernel 5.16-rc3, 5.15.X under root
- mkdir mnt
- mount -t f2fs tmp1.img mnt
- touch tmp
- cp tmp mnt
F2FS-fs (loop0): sanity_check_inode: inode (ino=49) extent info [5942, 4294180864, 4] is incorrect, run fsck to fix F2FS-fs (loop0): f2fs_check_nid_range: out-of-range nid=31340049, run fsck to fix. BUG: kernel NULL pointer dereference, address: 0000000000000000 folio_mark_dirty+0x33/0x50 move_data_page+0x2dd/0x460 [f2fs] do_garbage_collect+0xc18/0x16a0 [f2fs] f2fs_gc+0x1d3/0xd90 [f2fs] f2fs_balance_fs+0x13a/0x570 [f2fs] f2fs_create+0x285/0x840 [f2fs] path_openat+0xe6d/0x1040 do_filp_open+0xc5/0x140 do_sys_openat2+0x23a/0x310 do_sys_open+0x57/0x80
The root cause is for special file: e.g. character, block, fifo or socket file, f2fs doesn't assign address space operations pointer array for mapping->a_ops field, so, in a fuzzed image, SSA table indicates a data block belong to special file, when f2fs tries to migrate that block, it causes NULL pointer access once move_data_page() calls a_ops->set_dirty_page().
Cc: stable@vger.kernel.org Reported-by: Wenqing Liu wenqingliu0120@gmail.com Signed-off-by: Chao Yu chao@kernel.org Signed-off-by: Jaegeuk Kim jaegeuk@kernel.org Signed-off-by: Kazunori Kobayashi kazunori.kobayashi@miraclelinux.com
fs/f2fs/gc.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/fs/f2fs/gc.c b/fs/f2fs/gc.c
Also applied to 5.4.y and 4.14.y, you can't forget those :)
thanks,
greg k-h