[syzbot] [crypto?] general protection fault in cryptd_hash_export

[syzbot <syzbot+e79818f5c12416aba9de@syzkaller.appspotmail.com>]

Hello,

syzbot found the following issue on:

HEAD commit:    ded5c1a16ec6 Merge branch 'tools-ynl-gen-code-gen-improvem..
git tree:       net-next
console+strace: https://syzkaller.appspot.com/x/log.txt?x=104cdef1280000
kernel config:  https://syzkaller.appspot.com/x/.config?x=526f919910d4a671
dashboard link: https://syzkaller.appspot.com/bug?extid=e79818f5c12416aba9de
compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=13c6193b280000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=16c7a795280000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/ffd66beb6784/disk-ded5c1a1.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/e7336ae5a7bf/vmlinux-ded5c1a1.xz
kernel image: https://storage.googleapis.com/syzbot-assets/10ded02dc7e2/bzImage-ded5c1a1.xz

The issue was bisected to:

commit c662b043cdca89bf0f03fc37251000ac69a3a548
Author: David Howells <dhowells@redhat.com>
Date:   Tue Jun 6 13:08:56 2023 +0000

    crypto: af_alg/hash: Support MSG_SPLICE_PAGES

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=11cfc8d9280000
final oops:     https://syzkaller.appspot.com/x/report.txt?x=13cfc8d9280000
console output: https://syzkaller.appspot.com/x/log.txt?x=15cfc8d9280000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+e79818f5c12416aba9de@syzkaller.appspotmail.com
Fixes: c662b043cdca ("crypto: af_alg/hash: Support MSG_SPLICE_PAGES")

general protection fault, probably for non-canonical address 0xdffffc0000000004: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000020-0x0000000000000027]
CPU: 1 PID: 5003 Comm: syz-executor195 Not tainted 6.4.0-rc5-syzkaller-00929-gded5c1a16ec6 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/25/2023
RIP: 0010:crypto_shash_alg include/crypto/hash.h:827 [inline]
RIP: 0010:crypto_shash_export include/crypto/hash.h:956 [inline]
RIP: 0010:cryptd_hash_export+0x47/0xa0 crypto/cryptd.c:636
Code: 00 fc ff df 4c 89 e2 48 c1 ea 03 80 3c 02 00 75 4e 48 b8 00 00 00 00 00 fc ff df 48 8b 5b 60 48 8d 7b 20 48 89 fa 48 c1 ea 03 <80> 3c 02 00 75 40 48 b8 00 00 00 00 00 fc ff df 48 8b 5b 20 48 8d
RSP: 0018:ffffc90003acfd48 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000004 RSI: ffffffff83e46723 RDI: 0000000000000020
RBP: ffff888015a96528 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: ffffffff81d71db5 R12: ffff88802945bb08
R13: 0000000000000001 R14: ffff88801aba6000 R15: ffff8880220c1648
FS:  0000555556eb3300(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000020004e80 CR3: 0000000076861000 CR4: 00000000003506e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 crypto_ahash_export include/crypto/hash.h:523 [inline]
 hash_accept+0x229/0x670 crypto/algif_hash.c:286
 do_accept+0x380/0x510 net/socket.c:1871
 __sys_accept4_file net/socket.c:1912 [inline]
 __sys_accept4+0x9a/0x120 net/socket.c:1942
 __do_sys_accept4 net/socket.c:1953 [inline]
 __se_sys_accept4 net/socket.c:1950 [inline]
 __x64_sys_accept4+0x97/0x100 net/socket.c:1950
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f6a9d4eac09
Code: 28 c3 e8 2a 14 00 00 66 2e 0f 1f 84 00 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 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fff241f3198 EFLAGS: 00000246 ORIG_RAX: 0000000000000120
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f6a9d4eac09
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000004
RBP: 00007f6a9d4aedb0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f6a9d4aee40
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:crypto_shash_alg include/crypto/hash.h:827 [inline]
RIP: 0010:crypto_shash_export include/crypto/hash.h:956 [inline]
RIP: 0010:cryptd_hash_export+0x47/0xa0 crypto/cryptd.c:636
Code: 00 fc ff df 4c 89 e2 48 c1 ea 03 80 3c 02 00 75 4e 48 b8 00 00 00 00 00 fc ff df 48 8b 5b 60 48 8d 7b 20 48 89 fa 48 c1 ea 03 <80> 3c 02 00 75 40 48 b8 00 00 00 00 00 fc ff df 48 8b 5b 20 48 8d
RSP: 0018:ffffc90003acfd48 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000004 RSI: ffffffff83e46723 RDI: 0000000000000020
RBP: ffff888015a96528 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000001 R11: ffffffff81d71db5 R12: ffff88802945bb08
R13: 0000000000000001 R14: ffff88801aba6000 R15: ffff8880220c1648
FS:  0000555556eb3300(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000555a4edc6008 CR3: 0000000076861000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess), 3 bytes skipped:
   0:	df 4c 89 e2          	fisttps -0x1e(%rcx,%rcx,4)
   4:	48 c1 ea 03          	shr    $0x3,%rdx
   8:	80 3c 02 00          	cmpb   $0x0,(%rdx,%rax,1)
   c:	75 4e                	jne    0x5c
   e:	48 b8 00 00 00 00 00 	movabs $0xdffffc0000000000,%rax
  15:	fc ff df
  18:	48 8b 5b 60          	mov    0x60(%rbx),%rbx
  1c:	48 8d 7b 20          	lea    0x20(%rbx),%rdi
  20:	48 89 fa             	mov    %rdi,%rdx
  23:	48 c1 ea 03          	shr    $0x3,%rdx
* 27:	80 3c 02 00          	cmpb   $0x0,(%rdx,%rax,1) <-- trapping instruction
  2b:	75 40                	jne    0x6d
  2d:	48 b8 00 00 00 00 00 	movabs $0xdffffc0000000000,%rax
  34:	fc ff df
  37:	48 8b 5b 20          	mov    0x20(%rbx),%rbx
  3b:	48                   	rex.W
  3c:	8d                   	.byte 0x8d


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