On Mon, Jan 08, 2018 at 12:58:11PM +0100, 'Dmitry Vyukov' via syzkaller-bugs wrote: > On Mon, Jan 8, 2018 at 12:55 PM, Dmitry Vyukov <dvyu...@google.com> wrote: > > On Mon, Jan 8, 2018 at 12:43 PM, syzbot > > <syzbot+40396d275b34b0dd5...@syzkaller.appspotmail.com> wrote: > >> Hello, > >> > >> syzkaller hit the following crash on > >> f66faae2f80a45feafc04ce63ef744ac4b6e8c05 > >> git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next.git/master > >> compiler: gcc (GCC) 7.1.1 20170620 > >> .config is attached > >> Raw console output is attached. > >> Unfortunately, I don't have any reproducer for this bug yet. > >> > >> > >> IMPORTANT: if you fix the bug, please add the following tag to the commit: > >> Reported-by: syzbot+40396d275b34b0dd5...@syzkaller.appspotmail.com > >> It will help syzbot understand when the bug is fixed. See footer for > >> details. > >> If you forward the report, please keep this part and the footer. > > > > > > This looks like an issue in kcm sockets, so +kcm maintainers. > > FTR, guilty file extraction was fixed to ignore kernel/workqueue.c: > https://github.com/google/syzkaller/commit/1014e5506e35965f3bad13fabb08666134d0b273 > Presumably for bugs in workqueue usually the caller is guilty. > > > >> device ip6_vti0 entered promiscuous mode > >> ================================================================== > >> BUG: KASAN: use-after-free in constant_test_bit > >> arch/x86/include/asm/bitops.h:325 [inline] > >> BUG: KASAN: use-after-free in work_is_static_object+0x39/0x40 > >> kernel/workqueue.c:443 > >> Read of size 8 at addr ffff8801beca5788 by task syz-executor2/12922 > >> > >> CPU: 0 PID: 12922 Comm: syz-executor2 Not tainted 4.15.0-rc5+ #178 > >> 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 > >> constant_test_bit arch/x86/include/asm/bitops.h:325 [inline] > >> work_is_static_object+0x39/0x40 kernel/workqueue.c:443 > >> debug_object_activate+0x36f/0x730 lib/debugobjects.c:470 > >> debug_work_activate kernel/workqueue.c:492 [inline] > >> __queue_work+0x163/0x1230 kernel/workqueue.c:1381 > >> queue_work_on+0x16a/0x1c0 kernel/workqueue.c:1487 > >> queue_work include/linux/workqueue.h:488 [inline] > >> strp_check_rcv+0x25/0x30 net/strparser/strparser.c:552 > >> kcm_attach net/kcm/kcmsock.c:1439 [inline] > >> kcm_attach_ioctl net/kcm/kcmsock.c:1460 [inline] > >> kcm_ioctl+0x82f/0x1690 net/kcm/kcmsock.c:1665 > >> sock_do_ioctl+0x65/0xb0 net/socket.c:956 > >> sock_ioctl+0x2c2/0x440 net/socket.c:1053 > >> vfs_ioctl fs/ioctl.c:46 [inline] > >> do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:686 > >> SYSC_ioctl fs/ioctl.c:701 [inline] > >> SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692 > >> entry_SYSCALL_64_fastpath+0x23/0x9a > >> RIP: 0033:0x452ac9 > >> RSP: 002b:00007f1bbd860c58 EFLAGS: 00000212 ORIG_RAX: 0000000000000010 > >> RAX: ffffffffffffffda RBX: 000000000071bea0 RCX: 0000000000452ac9 > >> RDX: 0000000020954ff8 RSI: 00000000000089e0 RDI: 0000000000000017 > >> RBP: 000000000000057b R08: 0000000000000000 R09: 0000000000000000 > >> R10: 0000000000000000 R11: 0000000000000212 R12: 00000000006f6428 > >> R13: 00000000ffffffff R14: 00007f1bbd8616d4 R15: 0000000000000000 > >> > >> Allocated by task 12922: > >> 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 > >> kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:489 > >> kmem_cache_alloc+0x12e/0x760 mm/slab.c:3544 > >> kmem_cache_zalloc include/linux/slab.h:678 [inline] > >> kcm_attach net/kcm/kcmsock.c:1394 [inline] > >> kcm_attach_ioctl net/kcm/kcmsock.c:1460 [inline] > >> kcm_ioctl+0x2d2/0x1690 net/kcm/kcmsock.c:1665 > >> sock_do_ioctl+0x65/0xb0 net/socket.c:956 > >> sock_ioctl+0x2c2/0x440 net/socket.c:1053 > >> vfs_ioctl fs/ioctl.c:46 [inline] > >> do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:686 > >> SYSC_ioctl fs/ioctl.c:701 [inline] > >> SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692 > >> entry_SYSCALL_64_fastpath+0x23/0x9a > >> > >> Freed by task 12929: > >> 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] > >> kmem_cache_free+0x83/0x2a0 mm/slab.c:3746 > >> kcm_unattach+0xe53/0x1510 net/kcm/kcmsock.c:1563 > >> kcm_unattach_ioctl net/kcm/kcmsock.c:1608 [inline] > >> kcm_ioctl+0xe54/0x1690 net/kcm/kcmsock.c:1675 > >> sock_do_ioctl+0x65/0xb0 net/socket.c:956 > >> sock_ioctl+0x2c2/0x440 net/socket.c:1053 > >> vfs_ioctl fs/ioctl.c:46 [inline] > >> do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:686 > >> SYSC_ioctl fs/ioctl.c:701 [inline] > >> SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692 > >> entry_SYSCALL_64_fastpath+0x23/0x9a > >> > >> The buggy address belongs to the object at ffff8801beca56c0 > >> which belongs to the cache kcm_psock_cache of size 544 > >> The buggy address is located 200 bytes inside of > >> 544-byte region [ffff8801beca56c0, ffff8801beca58e0) > >> The buggy address belongs to the page: > >> page:000000005180a80a count:1 mapcount:0 mapping:0000000058aa9a5c index:0x0 > >> compound_mapcount: 0 > >> flags: 0x2fffc0000008100(slab|head) > >> raw: 02fffc0000008100 ffff8801beca40c0 0000000000000000 000000010000000b > >> raw: ffff8801d31e8a48 ffff8801d31e8a48 ffff8801d3f6a380 0000000000000000 > >> page dumped because: kasan: bad access detected > >> > >> Memory state around the buggy address: > >> ffff8801beca5680: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb > >> ffff8801beca5700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > >>> > >>> ffff8801beca5780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > >> > >> ^ > >> ffff8801beca5800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > >> ffff8801beca5880: fb fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc > >> ================================================================== > >> > >> > >> --- > >> This bug is generated by a dumb bot. It may contain errors. > >> See https://goo.gl/tpsmEJ for details. > >> Direct all questions to syzkal...@googlegroups.com. > >> > >> syzbot will keep track of this bug report. > >> If you forgot to add the Reported-by tag, once the fix for this bug is > >> merged > >> into any tree, please reply to this email with: > >> #syz fix: exact-commit-title
This only happened 3 times, with no reproducer, and last occurred 105 days ago (Jan 23, on commit 2310035fa03f6). It looks *very* similar to "KASAN: use-after-free Read in get_work_pool" (https://syzkaller.appspot.com/bug?extid=ea75c0ffcd353d32515f064aaebefc5279e6161e) which was fixed by commit 2cc683e88c0c99 ("kcm: lock lower socket in kcm_attach"), so I'll make an educated guess and say this one was fixed by that too... #syz fix: kcm: lock lower socket in kcm_attach - Eric
