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

[Ard Biesheuvel]

(+ Stefan)

On Wed, 26 Sep 2018 at 22:24, syzbot
<syzbot+6d3612ba5e254e387153@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
>
> Hello,
>
> syzbot found the following crash on:
>
> HEAD commit:    739d0def85ca Merge branch 'hv_netvsc-Support-LRO-RSC-in-th..
> git tree:       net-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=1146ffae400000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=e79b9299baeb2298
> dashboard link: https://syzkaller.appspot.com/bug?extid=6d3612ba5e254e387153
> compiler:       gcc (GCC) 8.0.1 20180413 (experimental)
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=16200b9e400000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=102311c6400000
>
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+6d3612ba5e254e387153@xxxxxxxxxxxxxxxxxxxxxxxxx
>
> random: sshd: uninitialized urandom read (32 bytes read)
> ==================================================================
> BUG: KASAN: use-after-free in memcpy include/linux/string.h:345 [inline]
> BUG: KASAN: use-after-free in generic_gcmaes_encrypt+0xc6/0x186
> arch/x86/crypto/aesni-intel_glue.c:1291
> Read of size 12 at addr ffff8801d7ad0900 by task kworker/0:1/14
>
> CPU: 0 PID: 14 Comm: kworker/0:1 Not tainted 4.19.0-rc4+ #228
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> Google 01/01/2011
> Workqueue: pencrypt padata_parallel_worker
> Call Trace:
>   __dump_stack lib/dump_stack.c:77 [inline]
>   dump_stack+0x1c4/0x2b4 lib/dump_stack.c:113
>   print_address_description.cold.8+0x9/0x1ff mm/kasan/report.c:256
>   kasan_report_error mm/kasan/report.c:354 [inline]
>   kasan_report.cold.9+0x242/0x309 mm/kasan/report.c:412
>   check_memory_region_inline mm/kasan/kasan.c:260 [inline]
>   check_memory_region+0x13e/0x1b0 mm/kasan/kasan.c:267
>   memcpy+0x23/0x50 mm/kasan/kasan.c:302
>   memcpy include/linux/string.h:345 [inline]
>   generic_gcmaes_encrypt+0xc6/0x186 arch/x86/crypto/aesni-intel_glue.c:1291
>   crypto_aead_encrypt include/crypto/aead.h:335 [inline]
>   gcmaes_wrapper_encrypt+0x162/0x200 arch/x86/crypto/aesni-intel_glue.c:1127
>   crypto_aead_encrypt include/crypto/aead.h:335 [inline]
>   pcrypt_aead_enc+0xcb/0x190 crypto/pcrypt.c:143
>   padata_parallel_worker+0x49d/0x760 kernel/padata.c:86
>   process_one_work+0xc90/0x1b90 kernel/workqueue.c:2153
>   worker_thread+0x17f/0x1390 kernel/workqueue.c:2296
>   kthread+0x35a/0x420 kernel/kthread.c:246
>   ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:413
>
> Allocated by task 5474:
>   save_stack+0x43/0xd0 mm/kasan/kasan.c:448
>   set_track mm/kasan/kasan.c:460 [inline]
>   kasan_kmalloc+0xc7/0xe0 mm/kasan/kasan.c:553
>   kmem_cache_alloc_trace+0x152/0x750 mm/slab.c:3620
>   kmalloc include/linux/slab.h:513 [inline]
>   tls_set_sw_offload+0xcc4/0x14b0 net/tls/tls_sw.c:1741
>   do_tls_setsockopt_conf net/tls/tls_main.c:467 [inline]
>   do_tls_setsockopt net/tls/tls_main.c:514 [inline]
>   tls_setsockopt+0x689/0x770 net/tls/tls_main.c:533
>   sock_common_setsockopt+0x9a/0xe0 net/core/sock.c:3038
>   __sys_setsockopt+0x1ba/0x3c0 net/socket.c:1902
>   __do_sys_setsockopt net/socket.c:1913 [inline]
>   __se_sys_setsockopt net/socket.c:1910 [inline]
>   __x64_sys_setsockopt+0xbe/0x150 net/socket.c:1910
>   do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
>   entry_SYSCALL_64_after_hwframe+0x49/0xbe
>
> Freed by task 5472:
>   save_stack+0x43/0xd0 mm/kasan/kasan.c:448
>   set_track mm/kasan/kasan.c:460 [inline]
>   __kasan_slab_free+0x102/0x150 mm/kasan/kasan.c:521
>   kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528
>   __cache_free mm/slab.c:3498 [inline]
>   kfree+0xcf/0x230 mm/slab.c:3813
>   tls_sk_proto_close+0x5fd/0x750 net/tls/tls_main.c:277
>   inet_release+0x104/0x1f0 net/ipv4/af_inet.c:428
>   inet6_release+0x50/0x70 net/ipv6/af_inet6.c:458
>   __sock_release+0xd7/0x250 net/socket.c:579
>   sock_close+0x19/0x20 net/socket.c:1141
>   __fput+0x385/0xa30 fs/file_table.c:278
>   ____fput+0x15/0x20 fs/file_table.c:309
>   task_work_run+0x1e8/0x2a0 kernel/task_work.c:113
>   tracehook_notify_resume include/linux/tracehook.h:193 [inline]
>   exit_to_usermode_loop+0x318/0x380 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+0x6be/0x820 arch/x86/entry/common.c:293
>   entry_SYSCALL_64_after_hwframe+0x49/0xbe
>
> The buggy address belongs to the object at ffff8801d7ad0900
>   which belongs to the cache kmalloc-32 of size 32
> The buggy address is located 0 bytes inside of
>   32-byte region [ffff8801d7ad0900, ffff8801d7ad0920)
> The buggy address belongs to the page:
> page:ffffea00075eb400 count:1 mapcount:0 mapping:ffff8801da8001c0
> index:0xffff8801d7ad0fc1
> flags: 0x2fffc0000000100(slab)
> raw: 02fffc0000000100 ffffea00075eb948 ffffea00075ff688 ffff8801da8001c0
> raw: ffff8801d7ad0fc1 ffff8801d7ad0000 000000010000003f 0000000000000000
> page dumped because: kasan: bad access detected
>
> Memory state around the buggy address:
>   ffff8801d7ad0800: fb fb fb fb fc fc fc fc 00 00 fc fc fc fc fc fc
>   ffff8801d7ad0880: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
> > ffff8801d7ad0900: fb fb fb fb fc fc fc fc fb fb fb fb fc fc fc fc
>                     ^
>   ffff8801d7ad0980: fb fb fb fb fc fc fc fc 00 00 fc fc fc fc fc fc
>   ffff8801d7ad0a00: 00 00 00 00 fc fc fc fc 00 00 00 00 fc fc fc fc
> ==================================================================
>
>
> ---
> This bug is generated by a bot. It may contain errors.
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>
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