Re: KASAN: use-after-free Read in crypto_aead_free_instance

On Tue, Dec 19, 2017 at 11:48:01PM -0800, syzbot wrote:

Hello,

syzkaller hit the following crash on
032b4cc8ff84490c4bc7c4ef8c91e6d83a637538
git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/master
compiler: gcc (GCC) 7.1.1 20170620
.config is attached
Raw console output is attached.
C reproducer is attached
syzkaller reproducer is attached. See https://goo.gl/kgGztJ
for information about syzkaller reproducers


==================================================================
BUG: KASAN: use-after-free in crypto_aead_free_instance+0xc0/0xd0
crypto/aead.c:154
Read of size 8 at addr ffff8801c32cf240 by task cryptomgr_test/6646

CPU: 1 PID: 6646 Comm: cryptomgr_test Not tainted 4.15.0-rc3+ #132
Hardware name: Google Google Compute Engine/Google Compute Engine,
BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x194/0x257 lib/dump_stack.c:53
 print_address_description+0x73/0x250 mm/kasan/report.c:252
 kasan_report_error mm/kasan/report.c:351 [inline]
 kasan_report+0x25b/0x340 mm/kasan/report.c:409
 __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:430
 crypto_aead_free_instance+0xc0/0xd0 crypto/aead.c:154
 crypto_free_instance+0x6d/0x100 crypto/algapi.c:77
 crypto_destroy_instance+0x3c/0x80 crypto/algapi.c:85
 crypto_alg_put crypto/internal.h:116 [inline]
 crypto_remove_final+0x212/0x370 crypto/algapi.c:331
 crypto_alg_tested+0x445/0x6f0 crypto/algapi.c:320
 cryptomgr_test+0x17/0x30 crypto/algboss.c:226
 kthread+0x37a/0x440 kernel/kthread.c:238
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:441

Allocated by task 6641:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc+0xad/0xe0 mm/kasan/kasan.c:551
 kmem_cache_alloc_trace+0x136/0x750 mm/slab.c:3610
 kmalloc include/linux/slab.h:499 [inline]
 kzalloc include/linux/slab.h:688 [inline]
 pcrypt_create_aead crypto/pcrypt.c:291 [inline]
 pcrypt_create+0x137/0x6c0 crypto/pcrypt.c:346
 cryptomgr_probe+0x74/0x240 crypto/algboss.c:75
 kthread+0x37a/0x440 kernel/kthread.c:238
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:441

Freed by task 3335:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_slab_free+0x71/0xc0 mm/kasan/kasan.c:524
 __cache_free mm/slab.c:3488 [inline]
 kfree+0xca/0x250 mm/slab.c:3803
 crypto_larval_destroy+0x110/0x150 crypto/api.c:107
 crypto_alg_put crypto/internal.h:116 [inline]
 crypto_larval_kill+0x1e8/0x2e0 crypto/api.c:167
 crypto_alg_mod_lookup+0x178/0x1b0 crypto/api.c:283
 crypto_find_alg crypto/api.c:501 [inline]
 crypto_alloc_tfm+0xf3/0x2f0 crypto/api.c:534
 crypto_alloc_aead+0x2c/0x40 crypto/aead.c:342
 aead_bind+0x70/0x140 crypto/algif_aead.c:482
 alg_bind+0x1ab/0x440 crypto/af_alg.c:179
 SYSC_bind+0x1b4/0x3f0 net/socket.c:1454
 SyS_bind+0x24/0x30 net/socket.c:1440
 do_syscall_32_irqs_on arch/x86/entry/common.c:327 [inline]
 do_fast_syscall_32+0x3ee/0xf9d arch/x86/entry/common.c:389
 entry_SYSENTER_compat+0x51/0x60 arch/x86/entry/entry_64_compat.S:125

Probably the pcrypt_free() bug.

#syz dup: KASAN: use-after-free Read in __list_del_entry_valid (2)