On 2021/7/23 10:51, Chao Yu wrote:
> On 2021/7/23 10:41, Jack Qiu wrote:
>> On 2021/7/22 22:05, Chao Yu wrote:
>>> On 2021/7/22 12:41, Jack Qiu wrote:
>>>> The root cause is shrink_dcache_sb after sbi has been freed.
>>>> So call shrink_dcache_sb before free sbi and other resources.
>>>>
>>>> ==================================================================
>>>> BUG: KASAN: use-after-free in f2fs_evict_inode+0x31c/0xde5
>>>> Read of size 4 at addr ffff8881d97f0d50 by task syz-executor.3/8729
>>>>
>>>> PU: 1 PID: 8729 Comm: syz-executor.3 Not tainted
>>>> 4.19.195-00002-g67dceea04431-dirty #31
>>>
>>> Does this bug below to 4.19.195?
>
> I mean whether this bug exists in mainline? Not sure, I just doubt maybe
> we have fixed this issue, but forgot to backport it to 4.19 stable kernel.
>
Got it.
>>>
>> Yes, I believe ed2e621a95d704e6a4e904cc00524e8cbddda0c2 causes this bug.
>>
>> git describe --contains ed2e621a95d704e6a4e904cc00524e8cbddda0c2
>> v3.17-rc4~27^2~17
>>
>> @@ -1126,6 +1130,13 @@ static int f2fs_fill_super(struct super_block *sb,
>> void *data, int silent)
>> brelse(raw_super_buf);
>> free_sbi:
>> kfree(sbi); --- free sbi
>> +
>> + /* give only one another chance */
>> + if (retry) {
>> + retry = !retry;
>> + shrink_dcache_sb(sb); --- call f2fs_evict_inode(root inode),
>> it will access sbi
>> + goto try_onemore;
>> + }
>> return err;
>> }
>>
>>>> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
>>>> ?-20190727_073836-buildvm-ppc64le-16.ppc.fedoraproject.org-3.fc31
>>>> 04/01/2014
>>>> Call Trace:
>>>> dump_stack+0xe5/0x14b
>>>> ? f2fs_evict_inode+0x31c/0xde5
>>>> print_address_description+0x6c/0x237
>>>> ? f2fs_evict_inode+0x31c/0xde5
>>>> kasan_report.cold+0x88/0x2a3
>>>> f2fs_evict_inode+0x31c/0xde5
>>>> ? full_proxy_open.cold+0x12/0x12
>>>> evict+0x2cd/0x5f0
>>>> iput+0x3d9/0x6f0
>>>> dentry_unlink_inode+0x273/0x330
>>>> __dentry_kill+0x340/0x5e0
>>>> dentry_kill+0xb7/0x740
>>>> shrink_dentry_list+0x256/0x660
>>>> shrink_dcache_sb+0x11f/0x1d0
>>>> ? shrink_dentry_list+0x660/0x660
>>>> ? __kasan_slab_free+0x144/0x180
>>>> f2fs_fill_super+0x2a34/0x4a80
>>>> ? f2fs_sanity_check_ckpt.cold+0x2b6/0x2b6
>>>> ? wait_for_completion+0x3c0/0x3c0
>>>> ? set_blocksize+0x230/0x2b0
>>>> mount_bdev+0x2c1/0x370
>>>> ? f2fs_sanity_check_ckpt.cold+0x2b6/0x2b6
>>>> mount_fs+0x4c/0x1c0
>>>> vfs_kern_mount.part.0+0x60/0x3d0
>>>> do_mount+0x367/0x2570
>>>> ? kasan_unpoison_shadow+0x33/0x40
>>>> ? copy_mount_string+0x40/0x40
>>>> ? kmem_cache_alloc_trace+0x13f/0x2b0
>>>> ? _copy_from_user+0x94/0x100
>>>> ? copy_mount_options+0x1f1/0x2e0
>>>> ksys_mount+0xa0/0x100
>>>> __x64_sys_mount+0xbf/0x160
>>>> do_syscall_64+0xc2/0x190
>>>> entry_SYSCALL_64_after_hwframe+0x49/0xbe
>>>> RIP: 0033:0x47938e
>>>> Code: 48 c7 c1 b4 ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84
>>>> 00 00 00 00 00 90 f3 0f 1e fa 49 89 ca b8 a5 00 00 00 0f 05 <48> 3d 01
>>>> f0 ff ff 73 01 c3 48 c7 c1 b4 ff ff ff f7 d8 64 89 01 48
>>>> RSP: 002b:00007fed673b6a48 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
>>>> RAX: ffffffffffffffda RBX: 0000000020000200 RCX: 000000000047938e
>>>> RDX: 0000000020000000 RSI: 0000000020000100 RDI: 00007fed673b6aa0
>>>> RBP: 00007fed673b6ae0 R08: 00007fed673b6ae0 R09: 0000000020000000
>>>> R10: 0000000000000000 R11: 0000000000000246 R12: 0000000020000000
>>>> R13: 0000000020000100 R14: 00007fed673b6aa0 R15: 0000000020000b00
>>>>
>>>> Allocated by task 8729:
>>>> kasan_kmalloc+0xc2/0xe0
>>>> kmem_cache_alloc_trace+0x13f/0x2b0
>>>> f2fs_fill_super+0x124/0x4a80
>>>> mount_bdev+0x2c1/0x370
>>>> mount_fs+0x4c/0x1c0
>>>> vfs_kern_mount.part.0+0x60/0x3d0
>>>> do_mount+0x367/0x2570
>>>> ksys_mount+0xa0/0x100
>>>> __x64_sys_mount+0xbf/0x160
>>>> do_syscall_64+0xc2/0x190
>>>> entry_SYSCALL_64_after_hwframe+0x49/0xbe
>>>>
>>>> Freed by task 8729:
>>>> __kasan_slab_free+0x12f/0x180
>>>> kfree+0xfa/0x2a0
>>>> f2fs_fill_super+0x2a00/0x4a80
>>>> mount_bdev+0x2c1/0x370
>>>> mount_fs+0x4c/0x1c0
>>>> vfs_kern_mount.part.0+0x60/0x3d0
>>>> do_mount+0x367/0x2570
>>>> ksys_mount+0xa0/0x100
>>>> __x64_sys_mount+0xbf/0x160
>>>> do_syscall_64+0xc2/0x190
>>>> entry_SYSCALL_64_after_hwframe+0x49/0xbe
>>>>
>>>> Signed-off-by: Jack Qiu <[email protected]>
>>>> ---
>>>> fs/f2fs/super.c | 3 ++-
>>>> 1 file changed, 2 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
>>>> index 8fecd3050ccd..b041625e06ce 100644
>>>> --- a/fs/f2fs/super.c
>>>> +++ b/fs/f2fs/super.c
>>>> @@ -4229,6 +4229,8 @@ static int f2fs_fill_super(struct super_block *sb,
>>>> void *data, int silent)
>>>> free_compress_inode:
>>>> f2fs_destroy_compress_inode(sbi);
>>>> free_root_inode:
>>>> + if (retry_cnt > 0 && skip_recovery)
>>>> + shrink_dcache_sb(sb);
>>>
>>> Compare to 4.19, last f2fs adds evict_inodes() before
>>> f2fs_unregister_sysfs(),
>> Can not find *evict_inodes*, could you please elaborate more detail?
>
> Could you please check whether below patch can fix this issue?
>
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=812a95977fd2f0d1f220c716a98
>
> Thanks,
>
I will test it.
Thansk,
>>> could you please check whether this can fix the issue?
>> I have run the test more than 1 day w/ this patch, it will fail in 1 hour
>> before.
>> I believe this patch can fix *this* issue. But I'm not quite familiar with
>> shrink_dcache_sb,
>> maybe I miss other scenario. If you have other comment, please let me know.
>>
>> Thanks,
>>>
>>> Thanks,
>>>
>>>> dput(sb->s_root);
>>>> sb->s_root = NULL;
>>>> free_node_inode:
>>>> @@ -4285,7 +4287,6 @@ static int f2fs_fill_super(struct super_block *sb,
>>>> void *data, int silent)
>>>> /* give only one another chance */
>>>> if (retry_cnt > 0 && skip_recovery) {
>>>> retry_cnt--;
>>>> - shrink_dcache_sb(sb);
>>>> goto try_onemore;
>>>> }
>>>> return err;
>>>> --
>>>> 2.17.1
>>>>
>>> .
>>
> .
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