On 08/20/2018 07:46 PM, Eric Biggers wrote: > On Wed, Aug 15, 2018 at 09:35:03AM -0700, syzbot wrote: >> Hello, >> >> syzbot found the following crash on: >> >> HEAD commit: 5ed5da74de9e Add linux-next specific files for 20180813 >> git tree: linux-next >> console output: https://syzkaller.appspot.com/x/log.txt?x=13fd82c4400000 >> kernel config: https://syzkaller.appspot.com/x/.config?x=18edf0289d1b5ab >> dashboard link: https://syzkaller.appspot.com/bug?extid=94ee41ce442afe333d2e >> compiler: gcc (GCC) 8.0.1 20180413 (experimental) >> >> Unfortunately, I don't have any reproducer for this crash yet. >> >> IMPORTANT: if you fix the bug, please add the following tag to the commit: >> Reported-by: syzbot+94ee41ce442afe333d2e@xxxxxxxxxxxxxxxxxxxxxxxxx >> >> RDX: 00000000200002c0 RSI: 0000000000000005 RDI: 0000000000000004 >> RBP: 00000000009300a0 R08: 0000000000000000 R09: 0000000000000000 >> R10: 0000000000000f6a R11: 0000000000000246 R12: 0000000000000006 >> R13: 00000000004d3840 R14: 00000000004c85ae R15: 0000000000000003 >> ================================================================== >> BUG: KASAN: use-after-free in sha512_mb_flusher+0x572/0x610 >> arch/x86/crypto/sha512-mb/sha512_mb.c:940 >> Read of size 8 at addr ffff8801b35669d8 by task kworker/0:2/1879 >> >> CPU: 0 PID: 1879 Comm: kworker/0:2 Not tainted 4.18.0-next-20180813+ #37 >> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS >> Google 01/01/2011 >> Workqueue: crypto mcryptd_flusher >> Call Trace: >> __dump_stack lib/dump_stack.c:77 [inline] >> dump_stack+0x1c9/0x2b4 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+0x242/0x30d mm/kasan/report.c:412 >> __asan_report_load8_noabort+0x14/0x20 mm/kasan/report.c:433 >> sha512_mb_flusher+0x572/0x610 arch/x86/crypto/sha512-mb/sha512_mb.c:940 >> mcryptd_flusher+0x342/0x4b0 crypto/mcryptd.c:208 >> process_one_work+0xc73/0x1aa0 kernel/workqueue.c:2153 >> worker_thread+0x189/0x13c0 kernel/workqueue.c:2296 >> kthread+0x35a/0x420 kernel/kthread.c:246 >> ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:415 >> >> Allocated by task 18983: >> 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/0x720 mm/slab.c:3727 >> kmalloc include/linux/slab.h:518 [inline] >> sock_kmalloc+0x156/0x1f0 net/core/sock.c:1983 >> hash_accept_parent_nokey+0x58/0x2e0 crypto/algif_hash.c:438 >> hash_accept_parent+0x5b/0x80 crypto/algif_hash.c:465 >> af_alg_accept+0x127/0x7d0 crypto/af_alg.c:296 >> alg_accept+0x46/0x60 crypto/af_alg.c:332 >> __sys_accept4+0x3b2/0x8a0 net/socket.c:1589 >> __do_sys_accept4 net/socket.c:1624 [inline] >> __se_sys_accept4 net/socket.c:1621 [inline] >> __x64_sys_accept4+0x97/0xf0 net/socket.c:1621 >> do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290 >> entry_SYSCALL_64_after_hwframe+0x49/0xbe >> >> Freed by task 18979: >> 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+0xd9/0x210 mm/slab.c:3813 >> __sock_kfree_s net/core/sock.c:2004 [inline] >> sock_kfree_s+0x29/0x60 net/core/sock.c:2010 >> hash_sock_destruct+0x157/0x1c0 crypto/algif_hash.c:427 >> __sk_destruct+0x107/0xa60 net/core/sock.c:1560 >> sk_destruct+0x78/0x90 net/core/sock.c:1595 >> __sk_free+0xcf/0x300 net/core/sock.c:1606 >> sk_free+0x42/0x50 net/core/sock.c:1617 >> sock_put include/net/sock.h:1691 [inline] >> af_alg_release+0x6e/0x90 crypto/af_alg.c:126 >> __sock_release+0xd7/0x250 net/socket.c:580 >> sock_close+0x19/0x20 net/socket.c:1140 >> __fput+0x376/0x8a0 fs/file_table.c:279 >> ____fput+0x15/0x20 fs/file_table.c:312 >> 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 ffff8801b3566600 >> which belongs to the cache kmalloc-2048 of size 2048 >> The buggy address is located 984 bytes inside of >> 2048-byte region [ffff8801b3566600, ffff8801b3566e00) >> The buggy address belongs to the page: >> page:ffffea0006cd5980 count:1 mapcount:0 mapping:ffff8801dac00c40 index:0x0 >> compound_mapcount: 0 >> flags: 0x2fffc0000008100(slab|head) >> raw: 02fffc0000008100 ffffea0006cf2c08 ffffea000764ef08 ffff8801dac00c40 >> raw: 0000000000000000 ffff8801b3566600 0000000100000003 0000000000000000 >> page dumped because: kasan: bad access detected >> >> Memory state around the buggy address: >> ffff8801b3566880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >> ffff8801b3566900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >>> ffff8801b3566980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >> ^ >> ffff8801b3566a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >> ffff8801b3566a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >> ================================================================== >> >> > > This is probably the same root cause as the other sha512_mb use-after-free > (https://lkml.org/lkml/2018/8/15/296), see my reply there. > > #syz dup: KASAN: use-after-free Read in sha512_ctx_mgr_resubmit > > - Eric > Yes, I think it is similar to the previous report. Megha is working to debug it. Tim
