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SubjectRe: KASAN: slab-out-of-bounds Read in crypto_morus640_decrypt_chunk
From
syzbot has found a reproducer for the following crash on:

HEAD commit: f0dc7f9c6dd9 Merge git://git.kernel.org/pub/scm/linux/kern..
git tree: net-next
console output: https://syzkaller.appspot.com/x/log.txt?x=16685c1f800000
kernel config: https://syzkaller.appspot.com/x/.config?x=fa9c20c48788d1c1
dashboard link: https://syzkaller.appspot.com/bug?extid=1fafa9c4cf42df33f716
compiler: gcc (GCC) 8.0.1 20180413 (experimental)
syzkaller repro:https://syzkaller.appspot.com/x/repro.syz?x=1122e4cf800000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1794783f800000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+1fafa9c4cf42df33f716@syzkaller.appspotmail.com

random: sshd: uninitialized urandom read (32 bytes read)
random: sshd: uninitialized urandom read (32 bytes read)
random: sshd: uninitialized urandom read (32 bytes read)
random: sshd: uninitialized urandom read (32 bytes read)
==================================================================
BUG: KASAN: slab-out-of-bounds in crypto_morus640_load_a
crypto/morus640.c:111 [inline]
BUG: KASAN: slab-out-of-bounds in crypto_morus640_decrypt_chunk+0xcf8/0xd20
crypto/morus640.c:278
Read of size 4 at addr ffff8801d76dc848 by task syz-executor575/4437

CPU: 1 PID: 4437 Comm: syz-executor575 Not tainted 4.17.0+ #84
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0x1b9/0x294 lib/dump_stack.c:113
print_address_description+0x6c/0x20b mm/kasan/report.c:256
kasan_report_error mm/kasan/report.c:354 [inline]
kasan_report.cold.7+0x242/0x2fe mm/kasan/report.c:412
__asan_report_load4_noabort+0x14/0x20 mm/kasan/report.c:432
crypto_morus640_load_a crypto/morus640.c:111 [inline]
crypto_morus640_decrypt_chunk+0xcf8/0xd20 crypto/morus640.c:278
crypto_morus640_process_crypt.isra.12+0x153/0x230 crypto/morus640.c:376
crypto_morus640_crypt+0x42e/0x9f0 crypto/morus640.c:442
crypto_morus640_decrypt+0x23e/0x3d0 crypto/morus640.c:485
crypto_aead_decrypt include/crypto/aead.h:370 [inline]
_aead_recvmsg crypto/algif_aead.c:315 [inline]
aead_recvmsg+0x13cc/0x1ba0 crypto/algif_aead.c:334
sock_recvmsg_nosec net/socket.c:818 [inline]
sock_recvmsg+0xd0/0x110 net/socket.c:825
___sys_recvmsg+0x2b6/0x680 net/socket.c:2323
__sys_recvmsg+0x112/0x260 net/socket.c:2372
__do_sys_recvmsg net/socket.c:2382 [inline]
__se_sys_recvmsg net/socket.c:2379 [inline]
__x64_sys_recvmsg+0x78/0xb0 net/socket.c:2379
do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x43fef9
Code: 18 89 d0 c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 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 6b 45 00 00 c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffd6c88d3b8 EFLAGS: 00000207 ORIG_RAX: 000000000000002f
RAX: ffffffffffffffda RBX: 00000000004002c8 RCX: 000000000043fef9
RDX: 0000000000000000 RSI: 0000000020002840 RDI: 0000000000000004
RBP: 00000000006ca018 R08: 00000000004002c8 R09: 00000000004002c8
R10: 00000000004002c8 R11: 0000000000000207 R12: 0000000000401820
R13: 00000000004018b0 R14: 0000000000000000 R15: 0000000000000000

Allocated by task 4437:
save_stack+0x43/0xd0 mm/kasan/kasan.c:448
set_track mm/kasan/kasan.c:460 [inline]
kasan_kmalloc+0xc4/0xe0 mm/kasan/kasan.c:553
__do_kmalloc mm/slab.c:3718 [inline]
__kmalloc+0x14e/0x760 mm/slab.c:3727
kmalloc include/linux/slab.h:518 [inline]
kzalloc include/linux/slab.h:706 [inline]
skcipher_next_slow crypto/skcipher.c:253 [inline]
skcipher_walk_next+0x750/0x1850 crypto/skcipher.c:357
skcipher_walk_first+0x151/0x410 crypto/skcipher.c:442
skcipher_walk_aead_common+0x7f8/0xbc0 crypto/skcipher.c:539
skcipher_walk_aead_decrypt+0xc7/0x100 crypto/skcipher.c:572
crypto_morus640_process_crypt.isra.12+0x9c/0x230 crypto/morus640.c:370
crypto_morus640_crypt+0x42e/0x9f0 crypto/morus640.c:442
crypto_morus640_decrypt+0x23e/0x3d0 crypto/morus640.c:485
crypto_aead_decrypt include/crypto/aead.h:370 [inline]
_aead_recvmsg crypto/algif_aead.c:315 [inline]
aead_recvmsg+0x13cc/0x1ba0 crypto/algif_aead.c:334
sock_recvmsg_nosec net/socket.c:818 [inline]
sock_recvmsg+0xd0/0x110 net/socket.c:825
___sys_recvmsg+0x2b6/0x680 net/socket.c:2323
__sys_recvmsg+0x112/0x260 net/socket.c:2372
__do_sys_recvmsg net/socket.c:2382 [inline]
__se_sys_recvmsg net/socket.c:2379 [inline]
__x64_sys_recvmsg+0x78/0xb0 net/socket.c:2379
do_syscall_64+0x1b1/0x800 arch/x86/entry/common.c:290
entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 2800:
save_stack+0x43/0xd0 mm/kasan/kasan.c:448
set_track mm/kasan/kasan.c:460 [inline]
__kasan_slab_free+0x11a/0x170 mm/kasan/kasan.c:521
kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528
__cache_free mm/slab.c:3498 [inline]
kfree+0xd9/0x260 mm/slab.c:3813
single_release+0x8f/0xb0 fs/seq_file.c:609
__fput+0x353/0x890 fs/file_table.c:209
____fput+0x15/0x20 fs/file_table.c:243
task_work_run+0x1e4/0x290 kernel/task_work.c:113
tracehook_notify_resume include/linux/tracehook.h:192 [inline]
exit_to_usermode_loop+0x302/0x360 arch/x86/entry/common.c:166
prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline]
syscall_return_slowpath arch/x86/entry/common.c:268 [inline]
do_syscall_64+0x6ac/0x800 arch/x86/entry/common.c:293
entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff8801d76dc840
which belongs to the cache kmalloc-32 of size 32
The buggy address is located 8 bytes inside of
32-byte region [ffff8801d76dc840, ffff8801d76dc860)
The buggy address belongs to the page:
page:ffffea00075db700 count:1 mapcount:0 mapping:ffff8801da8001c0
index:0xffff8801d76dcfc1
flags: 0x2fffc0000000100(slab)
raw: 02fffc0000000100 ffff8801da801238 ffffea00075dcdc8 ffff8801da8001c0
raw: ffff8801d76dcfc1 ffff8801d76dc000 000000010000003b 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff8801d76dc700: fb fb fb fb fc fc fc fc 00 00 fc fc fc fc fc fc
ffff8801d76dc780: fb fb fb fb fc fc fc fc 00 00 fc fc fc fc fc fc
> ffff8801d76dc800: 00 00 00 00 fc fc fc fc 00 fc fc fc fc fc fc fc
^
ffff8801d76dc880: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
ffff8801d76dc900: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
==================================================================

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