On Mon, 30 Oct 2017 12:32:58 -0700, syzbot wrote: > Hello, > > syzkaller hit the following crash on > 36ef71cae353f88fd6e095e2aaa3e5953af1685d > git://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.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 disk_unblock_events+0x51/0x60 > block/genhd.c:1632 > Read of size 8 at addr ffff8801d9049a80 by task blkid/14807 > > CPU: 1 PID: 14807 Comm: blkid Not tainted 4.14.0-rc5-next-20171018+ #36 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS > Google 01/01/2011 > Call Trace: > __dump_stack lib/dump_stack.c:16 [inline] > dump_stack+0x194/0x257 lib/dump_stack.c:52 > 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 > disk_unblock_events+0x51/0x60 block/genhd.c:1632 > __blkdev_get+0x78d/0xf90 fs/block_dev.c:1535 > blkdev_get+0x3a1/0xad0 fs/block_dev.c:1591 > blkdev_open+0x1c9/0x250 fs/block_dev.c:1749 > do_dentry_open+0x664/0xd40 fs/open.c:752 > vfs_open+0x107/0x220 fs/open.c:866 > do_last fs/namei.c:3387 [inline] > path_openat+0x1151/0x3520 fs/namei.c:3527 > do_filp_open+0x25b/0x3b0 fs/namei.c:3562 > do_sys_open+0x502/0x6d0 fs/open.c:1059 > SYSC_open fs/open.c:1077 [inline] > SyS_open+0x2d/0x40 fs/open.c:1072 > entry_SYSCALL_64_fastpath+0x1f/0xbe > RIP: 0033:0x7ff2d528f120 > RSP: 002b:00007ffd153fa6d8 EFLAGS: 00000246 ORIG_RAX: 0000000000000002 > RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007ff2d528f120 > RDX: 00007ffd153fbf35 RSI: 0000000000000000 RDI: 00007ffd153fbf35 > RBP: 0000000000000082 R08: 0000000000000078 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000246 R12: 0000000001fca030 > R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000005 > > Allocated by task 14811: > 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_node_trace+0x150/0x750 mm/slab.c:3657 > kmalloc_node include/linux/slab.h:540 [inline] > kzalloc_node include/linux/slab.h:702 [inline] > alloc_disk_node+0xb4/0x4e0 block/genhd.c:1375 > alloc_disk+0x18/0x20 block/genhd.c:1359 > loop_add+0x45c/0xa50 drivers/block/loop.c:1808 > loop_probe+0x16d/0x1a0 drivers/block/loop.c:1915 > kobj_lookup+0x2ac/0x410 drivers/base/map.c:124 > get_gendisk+0x37/0x230 block/genhd.c:773 > bd_start_claiming fs/block_dev.c:1097 [inline] > blkdev_get+0x12d/0xad0 fs/block_dev.c:1584 > blkdev_open+0x1c9/0x250 fs/block_dev.c:1749 > do_dentry_open+0x664/0xd40 fs/open.c:752 > vfs_open+0x107/0x220 fs/open.c:866 > do_last fs/namei.c:3387 [inline] > path_openat+0x1151/0x3520 fs/namei.c:3527 > do_filp_open+0x25b/0x3b0 fs/namei.c:3562 > do_sys_open+0x502/0x6d0 fs/open.c:1059 > SYSC_open fs/open.c:1077 [inline] > SyS_open+0x2d/0x40 fs/open.c:1072 > entry_SYSCALL_64_fastpath+0x1f/0xbe > > Freed by task 14807: > 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:3492 [inline] > kfree+0xca/0x250 mm/slab.c:3807 > disk_release+0x327/0x410 block/genhd.c:1218 > device_release+0x7c/0x200 drivers/base/core.c:814 > kobject_cleanup lib/kobject.c:648 [inline] > kobject_release lib/kobject.c:677 [inline] > kref_put include/linux/kref.h:70 [inline] > kobject_put+0x14c/0x240 lib/kobject.c:694 > put_disk+0x23/0x30 block/genhd.c:1440 > __blkdev_get+0x6ed/0xf90 fs/block_dev.c:1528 > blkdev_get+0x3a1/0xad0 fs/block_dev.c:1591 > blkdev_open+0x1c9/0x250 fs/block_dev.c:1749 > do_dentry_open+0x664/0xd40 fs/open.c:752 > vfs_open+0x107/0x220 fs/open.c:866 > do_last fs/namei.c:3387 [inline] > path_openat+0x1151/0x3520 fs/namei.c:3527 > do_filp_open+0x25b/0x3b0 fs/namei.c:3562 > do_sys_open+0x502/0x6d0 fs/open.c:1059 > SYSC_open fs/open.c:1077 [inline] > SyS_open+0x2d/0x40 fs/open.c:1072 > entry_SYSCALL_64_fastpath+0x1f/0xbe > > The buggy address belongs to the object at ffff8801d9049500 > which belongs to the cache kmalloc-2048 of size 2048 > The buggy address is located 1408 bytes inside of > 2048-byte region [ffff8801d9049500, ffff8801d9049d00) > The buggy address belongs to the page: > page:ffffea0007641200 count:1 mapcount:0 mapping:ffff8801d9048400 index:0x0 > compound_mapcount: 0 > flags: 0x200000000008100(slab|head) > raw: 0200000000008100 ffff8801d9048400 0000000000000000 0000000100000003 > raw: ffffea000748e5a0 ffffea0007063920 ffff8801dac00c40 0000000000000000 > page dumped because: kasan: bad access detected > > Memory state around the buggy address: > ffff8801d9049980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ffff8801d9049a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > > ffff8801d9049a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ^ > ffff8801d9049b00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ffff8801d9049b80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ================================================================== > > > --- > This bug is generated by a dumb bot. It may contain errors. > See https://goo.gl/tpsmEJ for details. > Direct all questions to syzkaller@xxxxxxxxxxxxxxxx. > > syzbot will keep track of this bug report. > Once a fix for this bug is committed, please reply to this email with: > #syz fix: exact-commit-title Last occurred 2 months ago, seems to have been fixed by commit 897366537fb6 (thanks Jan!), so telling syzbot: #syz fix: genhd: Fix use after free in __blkdev_get() - Eric
