[PATCH AUTOSEL 4.18 112/131] f2fs: fix to do sanity check with {sit,nat}_ver_bitmap_bytesize

From: Sasha Levin
Date: Sun Sep 02 2018 - 09:28:57 EST

From: Chao Yu <yuchao0@xxxxxxxxxx>

[ Upstream commit c77ec61ca0a49544ca81881cc5d5529858f7e196 ]

This patch adds to do sanity check with {sit,nat}_ver_bitmap_bytesize
during mount, in order to avoid accessing across cache boundary with
this abnormal bitmap size.

- Overview
buffer overrun in build_sit_info() when mounting a crafted f2fs image

- Reproduce

- Kernel message
[ 548.580867] F2FS-fs (loop0): Invalid log blocks per segment (8201)

[ 548.580877] F2FS-fs (loop0): Can't find valid F2FS filesystem in 1th superblock
[ 548.584979] ==================================================================
[ 548.586568] BUG: KASAN: use-after-free in kmemdup+0x36/0x50
[ 548.587715] Read of size 64 at addr ffff8801e9c265ff by task mount/1295

[ 548.589428] CPU: 1 PID: 1295 Comm: mount Not tainted 4.18.0-rc1+ #4
[ 548.589432] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014
[ 548.589438] Call Trace:
[ 548.589474] dump_stack+0x7b/0xb5
[ 548.589487] print_address_description+0x70/0x290
[ 548.589492] kasan_report+0x291/0x390
[ 548.589496] ? kmemdup+0x36/0x50
[ 548.589509] check_memory_region+0x139/0x190
[ 548.589514] memcpy+0x23/0x50
[ 548.589518] kmemdup+0x36/0x50
[ 548.589545] f2fs_build_segment_manager+0x8fa/0x3410
[ 548.589551] ? __asan_loadN+0xf/0x20
[ 548.589560] ? f2fs_sanity_check_ckpt+0x1be/0x240
[ 548.589566] ? f2fs_flush_sit_entries+0x10c0/0x10c0
[ 548.589587] ? __put_user_ns+0x40/0x40
[ 548.589604] ? find_next_bit+0x57/0x90
[ 548.589610] f2fs_fill_super+0x194b/0x2b40
[ 548.589617] ? f2fs_commit_super+0x1b0/0x1b0
[ 548.589637] ? set_blocksize+0x90/0x140
[ 548.589651] mount_bdev+0x1c5/0x210
[ 548.589655] ? f2fs_commit_super+0x1b0/0x1b0
[ 548.589667] f2fs_mount+0x15/0x20
[ 548.589672] mount_fs+0x60/0x1a0
[ 548.589683] ? alloc_vfsmnt+0x309/0x360
[ 548.589688] vfs_kern_mount+0x6b/0x1a0
[ 548.589699] do_mount+0x34a/0x18c0
[ 548.589710] ? lockref_put_or_lock+0xcf/0x160
[ 548.589716] ? copy_mount_string+0x20/0x20
[ 548.589728] ? memcg_kmem_put_cache+0x1b/0xa0
[ 548.589734] ? kasan_check_write+0x14/0x20
[ 548.589740] ? _copy_from_user+0x6a/0x90
[ 548.589744] ? memdup_user+0x42/0x60
[ 548.589750] ksys_mount+0x83/0xd0
[ 548.589755] __x64_sys_mount+0x67/0x80
[ 548.589781] do_syscall_64+0x78/0x170
[ 548.589797] entry_SYSCALL_64_after_hwframe+0x44/0xa9
[ 548.589820] RIP: 0033:0x7f76fc331b9a
[ 548.589821] Code: 48 8b 0d 01 c3 2b 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d ce c2 2b 00 f7 d8 64 89 01 48
[ 548.589880] RSP: 002b:00007ffd4f0a0e48 EFLAGS: 00000206 ORIG_RAX: 00000000000000a5
[ 548.589890] RAX: ffffffffffffffda RBX: 000000000146c030 RCX: 00007f76fc331b9a
[ 548.589892] RDX: 000000000146c210 RSI: 000000000146df30 RDI: 0000000001474ec0
[ 548.589895] RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000013
[ 548.589897] R10: 00000000c0ed0000 R11: 0000000000000206 R12: 0000000001474ec0
[ 548.589900] R13: 000000000146c210 R14: 0000000000000000 R15: 0000000000000003

[ 548.590242] The buggy address belongs to the page:
[ 548.591243] page:ffffea0007a70980 count:0 mapcount:0 mapping:0000000000000000 index:0x0
[ 548.592886] flags: 0x2ffff0000000000()
[ 548.593665] raw: 02ffff0000000000 dead000000000100 dead000000000200 0000000000000000
[ 548.595258] raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000
[ 548.603713] page dumped because: kasan: bad access detected

[ 548.605203] Memory state around the buggy address:
[ 548.606198] ffff8801e9c26480: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
[ 548.607676] ffff8801e9c26500: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
[ 548.609157] >ffff8801e9c26580: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
[ 548.610629] ^
[ 548.612088] ffff8801e9c26600: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
[ 548.613674] ffff8801e9c26680: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
[ 548.615141] ==================================================================
[ 548.616613] Disabling lock debugging due to kernel taint
[ 548.622871] WARNING: CPU: 1 PID: 1295 at mm/page_alloc.c:4065 __alloc_pages_slowpath+0xe4a/0x1420
[ 548.622878] Modules linked in: snd_hda_codec_generic snd_hda_intel snd_hda_codec snd_hwdep snd_hda_core snd_pcm snd_timer snd mac_hid i2c_piix4 soundcore ib_iser rdma_cm iw_cm ib_cm ib_core iscsi_tcp libiscsi_tcp libiscsi scsi_transport_iscsi raid10 raid456 async_raid6_recov async_memcpy async_pq async_xor async_tx raid1 raid0 multipath linear 8139too crct10dif_pclmul crc32_pclmul qxl drm_kms_helper syscopyarea aesni_intel sysfillrect sysimgblt fb_sys_fops ttm drm aes_x86_64 crypto_simd cryptd 8139cp glue_helper mii pata_acpi floppy
[ 548.623217] CPU: 1 PID: 1295 Comm: mount Tainted: G B 4.18.0-rc1+ #4
[ 548.623219] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014
[ 548.623226] RIP: 0010:__alloc_pages_slowpath+0xe4a/0x1420
[ 548.623227] Code: ff ff 01 89 85 c8 fe ff ff e9 91 fc ff ff 41 89 c5 e9 5c fc ff ff 0f 0b 89 f8 25 ff ff f7 ff 89 85 8c fe ff ff e9 d5 f2 ff ff <0f> 0b e9 65 f2 ff ff 65 8b 05 38 81 d2 47 f6 c4 01 74 1c 65 48 8b
[ 548.623281] RSP: 0018:ffff8801f28c7678 EFLAGS: 00010246
[ 548.623284] RAX: 0000000000000000 RBX: 00000000006040c0 RCX: ffffffffb82f73b7
[ 548.623287] RDX: 1ffff1003e518eeb RSI: 000000000000000c RDI: 0000000000000000
[ 548.623290] RBP: ffff8801f28c7880 R08: 0000000000000000 R09: ffffed0047fff2c5
[ 548.623292] R10: 0000000000000001 R11: ffffed0047fff2c4 R12: ffff8801e88de040
[ 548.623295] R13: 00000000006040c0 R14: 000000000000000c R15: ffff8801f28c7938
[ 548.623299] FS: 00007f76fca51840(0000) GS:ffff8801f6f00000(0000) knlGS:0000000000000000
[ 548.623302] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 548.623304] CR2: 00007f19b9171760 CR3: 00000001ed952000 CR4: 00000000000006e0
[ 548.623317] Call Trace:
[ 548.623325] ? kasan_check_read+0x11/0x20
[ 548.623330] ? __zone_watermark_ok+0x92/0x240
[ 548.623336] ? get_page_from_freelist+0x1c3/0x1d90
[ 548.623347] ? _raw_spin_lock_irqsave+0x2a/0x60
[ 548.623353] ? warn_alloc+0x250/0x250
[ 548.623358] ? save_stack+0x46/0xd0
[ 548.623361] ? kasan_kmalloc+0xad/0xe0
[ 548.623366] ? __isolate_free_page+0x2a0/0x2a0
[ 548.623370] ? mount_fs+0x60/0x1a0
[ 548.623374] ? vfs_kern_mount+0x6b/0x1a0
[ 548.623378] ? do_mount+0x34a/0x18c0
[ 548.623383] ? ksys_mount+0x83/0xd0
[ 548.623387] ? __x64_sys_mount+0x67/0x80
[ 548.623391] ? do_syscall_64+0x78/0x170
[ 548.623396] ? entry_SYSCALL_64_after_hwframe+0x44/0xa9
[ 548.623401] __alloc_pages_nodemask+0x3c5/0x400
[ 548.623407] ? __alloc_pages_slowpath+0x1420/0x1420
[ 548.623412] ? __mutex_lock_slowpath+0x20/0x20
[ 548.623417] ? kvmalloc_node+0x31/0x80
[ 548.623424] alloc_pages_current+0x75/0x110
[ 548.623436] kmalloc_order+0x24/0x60
[ 548.623442] kmalloc_order_trace+0x24/0xb0
[ 548.623448] __kmalloc_track_caller+0x207/0x220
[ 548.623455] ? f2fs_build_node_manager+0x399/0xbb0
[ 548.623460] kmemdup+0x20/0x50
[ 548.623465] f2fs_build_node_manager+0x399/0xbb0
[ 548.623470] f2fs_fill_super+0x195e/0x2b40
[ 548.623477] ? f2fs_commit_super+0x1b0/0x1b0
[ 548.623481] ? set_blocksize+0x90/0x140
[ 548.623486] mount_bdev+0x1c5/0x210
[ 548.623489] ? f2fs_commit_super+0x1b0/0x1b0
[ 548.623495] f2fs_mount+0x15/0x20
[ 548.623498] mount_fs+0x60/0x1a0
[ 548.623503] ? alloc_vfsmnt+0x309/0x360
[ 548.623508] vfs_kern_mount+0x6b/0x1a0
[ 548.623513] do_mount+0x34a/0x18c0
[ 548.623518] ? lockref_put_or_lock+0xcf/0x160
[ 548.623523] ? copy_mount_string+0x20/0x20
[ 548.623528] ? memcg_kmem_put_cache+0x1b/0xa0
[ 548.623533] ? kasan_check_write+0x14/0x20
[ 548.623537] ? _copy_from_user+0x6a/0x90
[ 548.623542] ? memdup_user+0x42/0x60
[ 548.623547] ksys_mount+0x83/0xd0
[ 548.623552] __x64_sys_mount+0x67/0x80
[ 548.623557] do_syscall_64+0x78/0x170
[ 548.623562] entry_SYSCALL_64_after_hwframe+0x44/0xa9
[ 548.623566] RIP: 0033:0x7f76fc331b9a
[ 548.623567] Code: 48 8b 0d 01 c3 2b 00 f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d ce c2 2b 00 f7 d8 64 89 01 48
[ 548.623632] RSP: 002b:00007ffd4f0a0e48 EFLAGS: 00000206 ORIG_RAX: 00000000000000a5
[ 548.623636] RAX: ffffffffffffffda RBX: 000000000146c030 RCX: 00007f76fc331b9a
[ 548.623639] RDX: 000000000146c210 RSI: 000000000146df30 RDI: 0000000001474ec0
[ 548.623641] RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000013
[ 548.623643] R10: 00000000c0ed0000 R11: 0000000000000206 R12: 0000000001474ec0
[ 548.623646] R13: 000000000146c210 R14: 0000000000000000 R15: 0000000000000003
[ 548.623650] ---[ end trace 4ce02f25ff7d3df5 ]---
[ 548.623656] F2FS-fs (loop0): Failed to initialize F2FS node manager
[ 548.627936] F2FS-fs (loop0): Invalid log blocks per segment (8201)

[ 548.627940] F2FS-fs (loop0): Can't find valid F2FS filesystem in 1th superblock
[ 548.635835] F2FS-fs (loop0): Failed to initialize F2FS node manager

- Location
https://elixir.bootlin.com/linux/v4.18-rc1/source/fs/f2fs/segment.c#L3578

sit_i->sit_bitmap = kmemdup(src_bitmap, bitmap_size, GFP_KERNEL);

Buffer overrun happens when doing memcpy. I suspect there is missing (inconsistent) checks on bitmap_size.

Reported by Wen Xu (wen.xu@xxxxxxxxxx) from SSLab, Gatech.

Reported-by: Wen Xu <wen.xu@xxxxxxxxxx>
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 | 21 +++++++++++++++++++--
1 file changed, 19 insertions(+), 2 deletions(-)

diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index a4ac297e66df..128d489acebb 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -2282,12 +2282,17 @@ int f2fs_sanity_check_ckpt(struct f2fs_sb_info *sbi)
struct f2fs_checkpoint *ckpt = F2FS_CKPT(sbi);
unsigned int ovp_segments, reserved_segments;
unsigned int main_segs, blocks_per_seg;
+ unsigned int sit_segs, nat_segs;
+ unsigned int sit_bitmap_size, nat_bitmap_size;
+ unsigned int log_blocks_per_seg;
int i;

total = le32_to_cpu(raw_super->segment_count);
fsmeta = le32_to_cpu(raw_super->segment_count_ckpt);
- fsmeta += le32_to_cpu(raw_super->segment_count_sit);
- fsmeta += le32_to_cpu(raw_super->segment_count_nat);
+ sit_segs = le32_to_cpu(raw_super->segment_count_sit);
+ fsmeta += sit_segs;
+ nat_segs = le32_to_cpu(raw_super->segment_count_nat);
+ fsmeta += nat_segs;
fsmeta += le32_to_cpu(ckpt->rsvd_segment_count);
fsmeta += le32_to_cpu(raw_super->segment_count_ssa);

@@ -2318,6 +2323,18 @@ int f2fs_sanity_check_ckpt(struct f2fs_sb_info *sbi)
return 1;
}

+ sit_bitmap_size = le32_to_cpu(ckpt->sit_ver_bitmap_bytesize);
+ nat_bitmap_size = le32_to_cpu(ckpt->nat_ver_bitmap_bytesize);
+ log_blocks_per_seg = le32_to_cpu(raw_super->log_blocks_per_seg);
+
+ if (sit_bitmap_size != ((sit_segs / 2) << log_blocks_per_seg) / 8 ||
+ nat_bitmap_size != ((nat_segs / 2) << log_blocks_per_seg) / 8) {
+ f2fs_msg(sbi->sb, KERN_ERR,
+ "Wrong bitmap size: sit: %u, nat:%u",
+ sit_bitmap_size, nat_bitmap_size);
+ return 1;
+ }
+
if (unlikely(f2fs_cp_error(sbi))) {
f2fs_msg(sbi->sb, KERN_ERR, "A bug case: need to run fsck");
return 1;
--
2.17.1