On Wed, Oct 25, 2023 at 08:54:32AM +0000, Kazunori Kobayashi wrote: > From: Chao Yu <chao@xxxxxxxxxx> > > 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 > > 1. mkdir mnt > 2. mount -t f2fs tmp1.img mnt > 3. touch tmp > 4. 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@xxxxxxxxxxxxxxx > Reported-by: Wenqing Liu <wenqingliu0120@xxxxxxxxx> > Signed-off-by: Chao Yu <chao@xxxxxxxxxx> > Signed-off-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx> > Signed-off-by: Kazunori Kobayashi <kazunori.kobayashi@xxxxxxxxxxxxxxxx> > --- > 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
