[syzbot] KASAN: use-after-free Read in skcipher_walk_next

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 4fa56ad0 Merge tag 'for-linus' of git://git.kernel.org/pub..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=17dbd09ad00000
kernel config: https://syzkaller.appspot.com/x/.config?x=9320464bf47598bd
dashboard link: https://syzkaller.appspot.com/bug?extid=4061a98a8ab454dde8ff

Unfortunately, I don't have any reproducer for this issue yet.

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+4061a9...@syzkaller.appspotmail.com

==================================================================
BUG: KASAN: use-after-free in memcpy include/linux/fortify-string.h:191 [inline]
BUG: KASAN: use-after-free in skcipher_next_copy crypto/skcipher.c:292 [inline]
BUG: KASAN: use-after-free in skcipher_walk_next+0xb69/0x1680 crypto/skcipher.c:379
Read of size 2785 at addr ffff8880781c0000 by task kworker/u4:3/204

CPU: 0 PID: 204 Comm: kworker/u4:3 Not tainted 5.12.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: pencrypt_parallel padata_parallel_worker
Call Trace:
__dump_stack lib/dump_stack.c:79 [inline]
dump_stack+0x141/0x1d7 lib/dump_stack.c:120
print_address_description.constprop.0.cold+0x5b/0x2f8 mm/kasan/report.c:232
__kasan_report mm/kasan/report.c:399 [inline]
kasan_report.cold+0x7c/0xd8 mm/kasan/report.c:416
check_region_inline mm/kasan/generic.c:180 [inline]
kasan_check_range+0x13d/0x180 mm/kasan/generic.c:186
memcpy+0x20/0x60 mm/kasan/shadow.c:65
memcpy include/linux/fortify-string.h:191 [inline]
skcipher_next_copy crypto/skcipher.c:292 [inline]
skcipher_walk_next+0xb69/0x1680 crypto/skcipher.c:379
skcipher_walk_done+0x7a3/0xf00 crypto/skcipher.c:159
gcmaes_crypt_by_sg+0x377/0x8a0 arch/x86/crypto/aesni-intel_glue.c:694

The buggy address belongs to the page:
page:ffffea0001e07000 refcount:0 mapcount:-128 mapping:0000000000000000 index:0x1 pfn:0x781c0
flags: 0xfff00000000000()
raw: 00fff00000000000 ffffea0001e06808 ffffea0001c67008 0000000000000000
raw: 0000000000000001 0000000000000004 00000000ffffff7f 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff8880781bff00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff8880781bff80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff8880781c0000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
^
ffff8880781c0080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
ffff8880781c0100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================


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[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.