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Date: Sat, 28 Jul 2018 18:23:33 -0700
From: Jaegeuk Kim <jaegeuk@...nel.org>
To: Chao Yu <yuchao0@...wei.com>
Cc: linux-f2fs-devel@...ts.sourceforge.net,
linux-kernel@...r.kernel.org, chao@...nel.org
Subject: Re: [PATCH v2 1/2] f2fs: fix to do sanity check with user_block_count
On 07/28, Chao Yu wrote:
> This patch fixs to do sanity check with user_block_count.
>
> - Overview
> Divide zero in utilization when mount() a corrupted f2fs image
>
> - Reproduce (4.18 upstream kernel)
>
> - Kernel message
> [ 564.099503] F2FS-fs (loop0): invalid crc value
> [ 564.101991] divide error: 0000 [#1] SMP KASAN PTI
> [ 564.103103] CPU: 1 PID: 1298 Comm: f2fs_discard-7: Not tainted 4.18.0-rc1+ #4
> [ 564.104584] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014
> [ 564.106624] RIP: 0010:issue_discard_thread+0x248/0x5c0
> [ 564.107692] Code: ff ff 48 8b bd e8 fe ff ff 41 8b 9d 4c 04 00 00 e8 cd b8 ad ff 41 8b 85 50 04 00 00 31 d2 48 8d 04 80 48 8d 04 80 48 c1 e0 02 <48> f7 f3 83 f8 50 7e 16 41 c7 86 7c ff ff ff 01 00 00 00 41 c7 86
> [ 564.111686] RSP: 0018:ffff8801f3117dc0 EFLAGS: 00010206
> [ 564.112775] RAX: 0000000000000384 RBX: 0000000000000000 RCX: ffffffffb88c1e03
> [ 564.114250] RDX: 0000000000000000 RSI: dffffc0000000000 RDI: ffff8801e3aa4850
> [ 564.115706] RBP: ffff8801f3117f00 R08: 1ffffffff751a1d0 R09: fffffbfff751a1d0
> [ 564.117177] R10: 0000000000000001 R11: fffffbfff751a1d0 R12: 00000000fffffffc
> [ 564.118634] R13: ffff8801e3aa4400 R14: ffff8801f3117ed8 R15: ffff8801e2050000
> [ 564.120094] FS: 0000000000000000(0000) GS:ffff8801f6f00000(0000) knlGS:0000000000000000
> [ 564.121748] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 564.122923] CR2: 000000000202b078 CR3: 00000001f11ac000 CR4: 00000000000006e0
> [ 564.124383] Call Trace:
> [ 564.124924] ? __issue_discard_cmd+0x480/0x480
> [ 564.125882] ? __sched_text_start+0x8/0x8
> [ 564.126756] ? __kthread_parkme+0xcb/0x100
> [ 564.127620] ? kthread_blkcg+0x70/0x70
> [ 564.128412] kthread+0x180/0x1d0
> [ 564.129105] ? __issue_discard_cmd+0x480/0x480
> [ 564.130029] ? kthread_associate_blkcg+0x150/0x150
> [ 564.131033] ret_from_fork+0x35/0x40
> [ 564.131794] 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
> [ 564.141798] ---[ end trace 4ce02f25ff7d3df5 ]---
> [ 564.142773] RIP: 0010:issue_discard_thread+0x248/0x5c0
> [ 564.143885] Code: ff ff 48 8b bd e8 fe ff ff 41 8b 9d 4c 04 00 00 e8 cd b8 ad ff 41 8b 85 50 04 00 00 31 d2 48 8d 04 80 48 8d 04 80 48 c1 e0 02 <48> f7 f3 83 f8 50 7e 16 41 c7 86 7c ff ff ff 01 00 00 00 41 c7 86
> [ 564.147776] RSP: 0018:ffff8801f3117dc0 EFLAGS: 00010206
> [ 564.148856] RAX: 0000000000000384 RBX: 0000000000000000 RCX: ffffffffb88c1e03
> [ 564.150424] RDX: 0000000000000000 RSI: dffffc0000000000 RDI: ffff8801e3aa4850
> [ 564.151906] RBP: ffff8801f3117f00 R08: 1ffffffff751a1d0 R09: fffffbfff751a1d0
> [ 564.153463] R10: 0000000000000001 R11: fffffbfff751a1d0 R12: 00000000fffffffc
> [ 564.154915] R13: ffff8801e3aa4400 R14: ffff8801f3117ed8 R15: ffff8801e2050000
> [ 564.156405] FS: 0000000000000000(0000) GS:ffff8801f6f00000(0000) knlGS:0000000000000000
> [ 564.158070] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 564.159279] CR2: 000000000202b078 CR3: 00000001f11ac000 CR4: 00000000000006e0
> [ 564.161043] ==================================================================
> [ 564.162587] BUG: KASAN: stack-out-of-bounds in from_kuid_munged+0x1d/0x50
> [ 564.163994] Read of size 4 at addr ffff8801f3117c84 by task f2fs_discard-7:/1298
>
> [ 564.165852] CPU: 1 PID: 1298 Comm: f2fs_discard-7: Tainted: G D 4.18.0-rc1+ #4
> [ 564.167593] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014
> [ 564.169522] Call Trace:
> [ 564.170057] dump_stack+0x7b/0xb5
> [ 564.170778] print_address_description+0x70/0x290
> [ 564.171765] kasan_report+0x291/0x390
> [ 564.172540] ? from_kuid_munged+0x1d/0x50
> [ 564.173408] __asan_load4+0x78/0x80
> [ 564.174148] from_kuid_munged+0x1d/0x50
> [ 564.174962] do_notify_parent+0x1f5/0x4f0
> [ 564.175808] ? send_sigqueue+0x390/0x390
> [ 564.176639] ? css_set_move_task+0x152/0x340
> [ 564.184197] do_exit+0x1290/0x1390
> [ 564.184950] ? __issue_discard_cmd+0x480/0x480
> [ 564.185884] ? mm_update_next_owner+0x380/0x380
> [ 564.186829] ? __sched_text_start+0x8/0x8
> [ 564.187672] ? __kthread_parkme+0xcb/0x100
> [ 564.188528] ? kthread_blkcg+0x70/0x70
> [ 564.189333] ? kthread+0x180/0x1d0
> [ 564.190052] ? __issue_discard_cmd+0x480/0x480
> [ 564.190983] rewind_stack_do_exit+0x17/0x20
>
> [ 564.192190] The buggy address belongs to the page:
> [ 564.193213] page:ffffea0007cc45c0 count:0 mapcount:0 mapping:0000000000000000 index:0x0
> [ 564.194856] flags: 0x2ffff0000000000()
> [ 564.195644] raw: 02ffff0000000000 0000000000000000 dead000000000200 0000000000000000
> [ 564.197247] raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000
> [ 564.198826] page dumped because: kasan: bad access detected
>
> [ 564.200299] Memory state around the buggy address:
> [ 564.201306] ffff8801f3117b80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> [ 564.202779] ffff8801f3117c00: 00 00 00 00 00 00 00 00 00 00 00 f3 f3 f3 f3 f3
> [ 564.204252] >ffff8801f3117c80: f3 f3 f3 00 00 00 00 00 00 00 00 00 f1 f1 f1 f1
> [ 564.205742] ^
> [ 564.206424] ffff8801f3117d00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
> [ 564.207908] ffff8801f3117d80: f3 f3 f3 f3 f3 f3 f3 f3 00 00 00 00 00 00 00 00
> [ 564.209389] ==================================================================
> [ 564.231795] F2FS-fs (loop0): Mounted with checkpoint version = 2
>
> - Location
> https://elixir.bootlin.com/linux/v4.18-rc1/source/fs/f2fs/segment.h#L586
> return div_u64((u64)valid_user_blocks(sbi) * 100,
> sbi->user_block_count);
> Missing checks on sbi->user_block_count.
>
> Reported-by: Wen Xu <wen.xu@...ech.edu>
> Signed-off-by: Chao Yu <yuchao0@...wei.com>
> ---
> v2:
> - replace le32_to_cpu with le64_to_cpu.
> fs/f2fs/super.c | 13 ++++++++++++-
> 1 file changed, 12 insertions(+), 1 deletion(-)
>
> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
> index 7fb51885a240..09009f5b3e87 100644
> --- a/fs/f2fs/super.c
> +++ b/fs/f2fs/super.c
> @@ -2283,6 +2283,8 @@ int f2fs_sanity_check_ckpt(struct f2fs_sb_info *sbi)
> unsigned int sit_segs, nat_segs;
> unsigned int sit_bitmap_size, nat_bitmap_size;
> unsigned int log_blocks_per_seg;
> + unsigned int user_block_count;
I modified
block_t user_block_count;
Thanks,
> + unsigned int segment_count_main;
> int i;
>
> total = le32_to_cpu(raw_super->segment_count);
> @@ -2307,6 +2309,16 @@ int f2fs_sanity_check_ckpt(struct f2fs_sb_info *sbi)
> return 1;
> }
>
> + user_block_count = le64_to_cpu(ckpt->user_block_count);
> + segment_count_main = le32_to_cpu(raw_super->segment_count_main);
> + log_blocks_per_seg = le32_to_cpu(raw_super->log_blocks_per_seg);
> + if (!user_block_count || user_block_count >=
> + segment_count_main << log_blocks_per_seg) {
> + f2fs_msg(sbi->sb, KERN_ERR,
> + "Wrong user_block_count: %u", user_block_count);
> + return 1;
> + }
> +
> main_segs = le32_to_cpu(raw_super->segment_count_main);
> blocks_per_seg = sbi->blocks_per_seg;
>
> @@ -2323,7 +2335,6 @@ int f2fs_sanity_check_ckpt(struct f2fs_sb_info *sbi)
>
> 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) {
> --
> 2.18.0.rc1
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