Re: BUG: unable to handle kernel NULL pointer dereference in sha1_mb_mgr_get_comp_job_avx2

[Eric Biggers]

On Wed, Sep 26, 2018 at 07:27:04AM -0700, syzbot wrote:
> Hello,
> 
> syzbot found the following crash on:
> 
> HEAD commit:    a38523185b40 erge tag 'libnvdimm-fixes-4.19-rc6' of git://..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=1767b7fa400000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=dfb440e26f0a6f6f
> dashboard link: https://syzkaller.appspot.com/bug?extid=87dbe4b17debcec16d71
> compiler:       gcc (GCC) 8.0.1 20180413 (experimental)
> 
> Unfortunately, I don't have any reproducer for this crash yet.
> 
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+87dbe4b17debcec16d71@xxxxxxxxxxxxxxxxxxxxxxxxx
> 
> BUG: unable to handle kernel NULL pointer dereference at 0000000000000034
> PGD 1b8b87067 P4D 1b8b87067 PUD 1b8b88067 PMD 0
> Oops: 0002 [#1] PREEMPT SMP KASAN
> CPU: 1 PID: 24 Comm: kworker/1:1 Not tainted 4.19.0-rc5+ #32
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> Google 01/01/2011
> Workqueue: crypto mcryptd_flusher
> RIP: 0010:sha1_mb_mgr_get_comp_job_avx2+0x62/0xba
> arch/x86/crypto/sha1-mb/sha1_mb_mgr_flush_avx2.S:256
> Code: 04 c4 e2 69 3b d3 c4 c1 79 7e d0 49 f7 c0 f0 ff ff ff 75 6e 49 6b d8
> 08 48 8d 9c 1f 08 01 00 00 48 8b 03 48 c7 03 00 00 00 00 <c7> 40 34 02 00 00
> 00 48 8b 9f 00 01 00 00 48 c1 e3 04 4c 09 c3 48
> kobject: 'loop1' (00000000307f8c2f): kobject_uevent_env
> RSP: 0018:ffff8801d94473c0 EFLAGS: 00010206
> RAX: 0000000000000000 RBX: ffff8801d4818688 RCX: 1ffff1003b2869e1
> RDX: 1ffffd1ffffa2591 RSI: ffffffff81454f3a RDI: ffff8801d4818580
> RBP: ffff8801d9447520 R08: 0000000000000000 R09: 0000000000000006
> kobject: 'loop1' (00000000307f8c2f): fill_kobj_path: path =
> '/devices/virtual/block/loop1'
> R10: 0000000000000000 R11: ffff8801d9434640 R12: ffff8801d94474f8
> R13: 0000000000000001 R14: ffff8801bb509720 R15: 0000000000000200
> FS:  0000000000000000(0000) GS:ffff8801dad00000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> kobject: 'loop4' (00000000fa342cfc): kobject_uevent_env
> CR2: 0000000000000034 CR3: 00000001b8b85000 CR4: 00000000001406e0
> kobject: 'loop4' (00000000fa342cfc): fill_kobj_path: path =
> '/devices/virtual/block/loop4'
> Call Trace:
>  sha1_mb_flusher+0x2f4/0x60b arch/x86/crypto/sha1-mb/sha1_mb.c:918
>  mcryptd_flusher+0x3af/0x520 crypto/mcryptd.c:208
>  process_one_work+0xc90/0x1b90 kernel/workqueue.c:2153
>  worker_thread+0x17f/0x1390 kernel/workqueue.c:2296
>  kthread+0x35a/0x420 kernel/kthread.c:246
>  ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:413
> Modules linked in:
> CR2: 0000000000000034
> ---[ end trace 7d3a48e5625a9543 ]---
> RIP: 0010:sha1_mb_mgr_get_comp_job_avx2+0x62/0xba
> arch/x86/crypto/sha1-mb/sha1_mb_mgr_flush_avx2.S:256
> Code: 04 c4 e2 69 3b d3 c4 c1 79 7e d0 49 f7 c0 f0 ff ff ff 75 6e 49 6b d8
> 08 48 8d 9c 1f 08 01 00 00 48 8b 03 48 c7 03 00 00 00 00 <c7> 40 34 02 00 00
> 00 48 8b 9f 00 01 00 00 48 c1 e3 04 4c 09 c3 48
> RSP: 0018:ffff8801d94473c0 EFLAGS: 00010206
> RAX: 0000000000000000 RBX: ffff8801d4818688 RCX: 1ffff1003b2869e1
> RDX: 1ffffd1ffffa2591 RSI: ffffffff81454f3a RDI: ffff8801d4818580
> RBP: ffff8801d9447520 R08: 0000000000000000 R09: 0000000000000006
> R10: 0000000000000000 R11: ffff8801d9434640 R12: ffff8801d94474f8
> R13: 0000000000000001 R14: ffff8801bb509720 R15: 0000000000000200
> FS:  0000000000000000(0000) GS:ffff8801dad00000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000000000000034 CR3: 00000001b8b85000 CR4: 00000000001406e0
> 
> 
> ---
> This bug is generated by a bot. It may contain errors.
> See https://goo.gl/tpsmEJ for more information about syzbot.
> syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxxx
> 
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> syzbot.

The "fix" for this is queued in cryptodev:

#syz fix: crypto: x86 - remove SHA multibuffer routines and mcryptd

- Eric