From: Chao Yu <yuchao0@xxxxxxxxxx> [ Upstream commit 42bf546c1fe3f3654bdf914e977acbc2b80a5be5 ] As Wen Xu reported in below link: https://bugzilla.kernel.org/show_bug.cgi?id=200183 - Overview Divide zero in reset_curseg() when mounting a crafted f2fs image - Reproduce - Kernel message [ 588.281510] divide error: 0000 [#1] SMP KASAN PTI [ 588.282701] CPU: 0 PID: 1293 Comm: mount Not tainted 4.18.0-rc1+ #4 [ 588.284000] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014 [ 588.286178] RIP: 0010:reset_curseg+0x94/0x1a0 [ 588.298166] RSP: 0018:ffff8801e88d7940 EFLAGS: 00010246 [ 588.299360] RAX: 0000000000000014 RBX: ffff8801e1d46d00 RCX: ffffffffb88bf60b [ 588.300809] RDX: 0000000000000000 RSI: dffffc0000000000 RDI: ffff8801e1d46d64 [ 588.305272] R13: 0000000000000000 R14: 0000000000000014 R15: 0000000000000000 [ 588.306822] FS: 00007fad85008840(0000) GS:ffff8801f6e00000(0000) knlGS:0000000000000000 [ 588.308456] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 588.309623] CR2: 0000000001705078 CR3: 00000001f30f8000 CR4: 00000000000006f0 [ 588.311085] Call Trace: [ 588.311637] f2fs_build_segment_manager+0x103f/0x3410 [ 588.316136] ? f2fs_commit_super+0x1b0/0x1b0 [ 588.317031] ? set_blocksize+0x90/0x140 [ 588.319473] f2fs_mount+0x15/0x20 [ 588.320166] mount_fs+0x60/0x1a0 [ 588.320847] ? alloc_vfsmnt+0x309/0x360 [ 588.321647] vfs_kern_mount+0x6b/0x1a0 [ 588.322432] do_mount+0x34a/0x18c0 [ 588.323175] ? strndup_user+0x46/0x70 [ 588.323937] ? copy_mount_string+0x20/0x20 [ 588.324793] ? memcg_kmem_put_cache+0x1b/0xa0 [ 588.325702] ? kasan_check_write+0x14/0x20 [ 588.326562] ? _copy_from_user+0x6a/0x90 [ 588.327375] ? memdup_user+0x42/0x60 [ 588.328118] ksys_mount+0x83/0xd0 [ 588.328808] __x64_sys_mount+0x67/0x80 [ 588.329607] do_syscall_64+0x78/0x170 [ 588.330400] entry_SYSCALL_64_after_hwframe+0x44/0xa9 [ 588.331461] RIP: 0033:0x7fad848e8b9a [ 588.336022] RSP: 002b:00007ffd7c5b6be8 EFLAGS: 00000206 ORIG_RAX: 00000000000000a5 [ 588.337547] RAX: ffffffffffffffda RBX: 00000000016f8030 RCX: 00007fad848e8b9a [ 588.338999] RDX: 00000000016f8210 RSI: 00000000016f9f30 RDI: 0000000001700ec0 [ 588.340442] RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000013 [ 588.341887] R10: 00000000c0ed0000 R11: 0000000000000206 R12: 0000000001700ec0 [ 588.343341] R13: 00000000016f8210 R14: 0000000000000000 R15: 0000000000000003 [ 588.354891] ---[ end trace 4ce02f25ff7d3df5 ]--- [ 588.355862] RIP: 0010:reset_curseg+0x94/0x1a0 [ 588.360742] RSP: 0018:ffff8801e88d7940 EFLAGS: 00010246 [ 588.361812] RAX: 0000000000000014 RBX: ffff8801e1d46d00 RCX: ffffffffb88bf60b [ 588.363485] RDX: 0000000000000000 RSI: dffffc0000000000 RDI: ffff8801e1d46d64 [ 588.365213] RBP: ffff8801e88d7968 R08: ffffed003c32266f R09: ffffed003c32266f [ 588.366661] R10: 0000000000000001 R11: ffffed003c32266e R12: ffff8801f0337700 [ 588.368110] R13: 0000000000000000 R14: 0000000000000014 R15: 0000000000000000 [ 588.370057] FS: 00007fad85008840(0000) GS:ffff8801f6e00000(0000) knlGS:0000000000000000 [ 588.372099] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 588.373291] CR2: 0000000001705078 CR3: 00000001f30f8000 CR4: 00000000000006f0 - Location https://elixir.bootlin.com/linux/latest/source/fs/f2fs/segment.c#L2147 curseg->zone = GET_ZONE_FROM_SEG(sbi, curseg->segno); If secs_per_zone is corrupted due to fuzzing test, it will cause divide zero operation when using GET_ZONE_FROM_SEG macro, so we should do more sanity check with secs_per_zone during mount to avoid this issue. Signed-off-by: Chao Yu <yuchao0@xxxxxxxxxx> Signed-off-by: Jaegeuk Kim <jaegeuk@xxxxxxxxxx> Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx> --- fs/f2fs/super.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c index 3995e926ba3a..a4ac297e66df 100644 --- a/fs/f2fs/super.c +++ b/fs/f2fs/super.c @@ -2229,9 +2229,9 @@ static int sanity_check_raw_super(struct f2fs_sb_info *sbi, return 1; } - if (secs_per_zone > total_sections) { + if (secs_per_zone > total_sections || !secs_per_zone) { f2fs_msg(sb, KERN_INFO, - "Wrong secs_per_zone (%u > %u)", + "Wrong secs_per_zone / total_sections (%u, %u)", secs_per_zone, total_sections); return 1; } -- 2.17.1
