BUG: bad usercopy in alg_setsockopt

[syzbot]

Hello,

syzkaller hit the following crash on
72bca2084a21edda74b802bc076083d5951f67b4
git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git/master
compiler: gcc (GCC) 7.1.1 20170620
.config is attached
Raw console output is attached.
Unfortunately, I don't have any reproducer for this bug yet.
CC: [james...@arm.com kees...@chromium.org keun-...@darkmatter.ae
lab...@redhat.com linux-...@vger.kernel.org linu...@kvack.org
mark.r...@arm.com mi...@kernel.org]

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Reported-by: syzbot+144bf0...@syzkaller.appspotmail.com
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usercopy: kernel memory overwrite attempt detected to 0000000012e47039
(kmalloc-1024) (952 bytes)
------------[ cut here ]------------
kernel BUG at mm/usercopy.c:72!
invalid opcode: 0000 [#1] SMP KASAN
Dumping ftrace buffer:
(ftrace buffer empty)
Modules linked in:
CPU: 1 PID: 8076 Comm: syz-executor7 Not tainted 4.15.0-rc5+ #173
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
RIP: 0010:report_usercopy mm/usercopy.c:64 [inline]
RIP: 0010:__check_object_size+0x3a2/0x4f0 mm/usercopy.c:264
RSP: 0018:ffff8801ce817d10 EFLAGS: 00010282
RAX: 0000000000000061 RBX: ffffffff8592bb60 RCX: 0000000000000000
RDX: 0000000000000061 RSI: ffffc90002d9c000 RDI: ffffed0039d02f96
RBP: ffff8801ce817e00 R08: 1ffff10039d02f24 R09: 0000000000000000
R10: 0000000056b703f8 R11: 0000000000000000 R12: ffffffff8592bb20
R13: ffff8801bf9b2950 R14: 00000000000003b8 R15: ffffea0006fe6c80
FS: 00007f4ad64a2700(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000071c000 CR3: 00000001c6703003 CR4: 00000000001606e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
check_object_size include/linux/thread_info.h:112 [inline]
check_copy_size include/linux/thread_info.h:143 [inline]
copy_from_user include/linux/uaccess.h:146 [inline]
alg_setkey crypto/af_alg.c:218 [inline]
alg_setsockopt+0x234/0x350 crypto/af_alg.c:254
SYSC_setsockopt net/socket.c:1821 [inline]
SyS_setsockopt+0x189/0x360 net/socket.c:1800
entry_SYSCALL_64_fastpath+0x23/0x9a
RIP: 0033:0x452ac9
RSP: 002b:00007f4ad64a1c58 EFLAGS: 00000212 ORIG_RAX: 0000000000000036
RAX: ffffffffffffffda RBX: 000000000071bea0 RCX: 0000000000452ac9
RDX: 0000000000000001 RSI: 0000000000000117 RDI: 0000000000000013
RBP: 0000000000000568 R08: 00000000000003b8 R09: 0000000000000000
R10: 0000000020b3aff0 R11: 0000000000000212 R12: 00000000006f6260
R13: 00000000ffffffff R14: 00007f4ad64a26d4 R15: 0000000000000000
Code: 48 0f 44 da e8 70 5b c0 ff 48 8b 85 28 ff ff ff 4d 89 f1 4c 89 e9 4c
89 e2 48 89 de 48 c7 c7 20 bc 92 85 49 89 c0 e8 e6 10 aa ff <0f> 0b 48 c7
c0 e0 b9 92 85 eb 96 48 c7 c0 20 ba 92 85 eb 8d 48
RIP: report_usercopy mm/usercopy.c:64 [inline] RSP: ffff8801ce817d10
RIP: __check_object_size+0x3a2/0x4f0 mm/usercopy.c:264 RSP: ffff8801ce817d10
---[ end trace 26ea5793f0ff2338 ]---
Kernel panic - not syncing: Fatal exception
Dumping ftrace buffer:
(ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..


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[Dmitry Vyukov]

#syz fix: crypto: pcrypt - fix freeing pcrypt instances

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