RE: WARNING in __kernel_read (2)

[David Laight]

> From: syzbot <syzbot+51177e4144d764827c45@xxxxxxxxxxxxxxxxxxxxxxxxx>
> Sent: 26 September 2020 03:58
> To: linux-fsdevel@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; syzkaller-bugs@xxxxxxxxxxxxxxxx;
> viro@xxxxxxxxxxxxxxxxxx
> Subject: WARNING in __kernel_read (2)

I suspect this is calling finit_module() on an fd
that doesn't have read permissions.

	David

> 
> Hello,
> 
> syzbot found the following issue on:
> 
> HEAD commit:    b10b8ad8 Add linux-next specific files for 20200921
> git tree:       linux-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=1437eff1900000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=3cf0782933432b43
> dashboard link: https://syzkaller.appspot.com/bug?extid=51177e4144d764827c45
> compiler:       gcc (GCC) 10.1.0-syz 20200507
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=10f9f08d900000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=13d67c81900000
> 
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+51177e4144d764827c45@xxxxxxxxxxxxxxxxxxxxxxxxx
> 
> ------------[ cut here ]------------
> WARNING: CPU: 0 PID: 7028 at fs/read_write.c:440 __kernel_read+0x80e/0xa10 fs/read_write.c:440
> Modules linked in:
> CPU: 0 PID: 7028 Comm: syz-executor458 Not tainted 5.9.0-rc5-next-20200921-syzkaller #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> RIP: 0010:__kernel_read+0x80e/0xa10 fs/read_write.c:440
> Code: 8a e8 c6 97 12 02 31 ff 89 c3 89 c6 e8 2b ac b3 ff 85 db 0f 85 6e 3b 55 06 49 c7 c5 ea ff ff ff
> e9 bd fd ff ff e8 b2 af b3 ff <0f> 0b 49 c7 c5 ea ff ff ff e9 aa fd ff ff e8 9f af b3 ff 48 89 ea
> RSP: 0018:ffffc90006027b38 EFLAGS: 00010293
> RAX: 0000000000000000 RBX: 0000000000000002 RCX: ffffffff81c1715b
> RDX: ffff888091eba480 RSI: ffffffff81c1787e RDI: 0000000000000005
> RBP: 000000000008801c R08: 0000000000000001 R09: ffff888091ebad88
> R10: 0000000000000000 R11: 0000000000000000 R12: ffff8880a16710c0
> R13: 0000000000000001 R14: ffffc90006027d08 R15: ffff8880a1671144
> FS:  00007efcd60f1700(0000) GS:ffff8880ae400000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000000020000000 CR3: 00000000a2dc5000 CR4: 00000000001506f0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
>  kernel_read+0x52/0x70 fs/read_write.c:471
>  kernel_read_file fs/exec.c:989 [inline]
>  kernel_read_file+0x2e5/0x620 fs/exec.c:952
>  kernel_read_file_from_fd+0x56/0xa0 fs/exec.c:1076
>  __do_sys_finit_module+0xe6/0x190 kernel/module.c:4066
>  do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
>  entry_SYSCALL_64_after_hwframe+0x44/0xa9
> RIP: 0033:0x44a639
> Code: e8 bc b4 02 00 48 83 c4 18 c3 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2
> 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 4b cc fb ff c3 66 2e 0f 1f 84 00 00 00 00
> RSP: 002b:00007efcd60f0db8 EFLAGS: 00000246 ORIG_RAX: 0000000000000139
> RAX: ffffffffffffffda RBX: 00000000006dbc68 RCX: 000000000044a639
> RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000004
> RBP: 00000000006dbc60 R08: 00007efcd60f1700 R09: 0000000000000000
> R10: 00007efcd60f1700 R11: 0000000000000246 R12: 00000000006dbc6c
> R13: 00007ffd3d8928ef R14: 00007efcd60f19c0 R15: 0000000000000001
> 
> 
> ---
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