On Thu, Dec 14, 2017 at 10:23 AM, syzbot <bot+9e3011b5e961675e736b38d6fd82ad12723a3fa3@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote: > syzkaller has found reproducer for the following crash on > 82bcf1def3b5f1251177ad47c44f7e17af039b4b > git://git.cmpxchg.org/linux-mmots.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 __read_once_size include/linux/compiler.h:183 > [inline] > BUG: KASAN: use-after-free in atomic_read arch/x86/include/asm/atomic.h:27 > [inline] > BUG: KASAN: use-after-free in refcount_inc_not_zero+0x16e/0x180 > lib/refcount.c:120 > Read of size 4 at addr ffff8801c51bb200 by task syzkaller711981/3156 > > CPU: 1 PID: 3156 Comm: syzkaller711981 Not tainted 4.15.0-rc2-mm1+ #39 > 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_load4_noabort+0x14/0x20 mm/kasan/report.c:429 > __read_once_size include/linux/compiler.h:183 [inline] > atomic_read arch/x86/include/asm/atomic.h:27 [inline] > refcount_inc_not_zero+0x16e/0x180 lib/refcount.c:120 > refcount_inc+0x15/0x50 lib/refcount.c:153 > get_ipc_ns include/linux/ipc_namespace.h:129 [inline] > __get_ns_from_inode ipc/mqueue.c:110 [inline] > get_ns_from_inode ipc/mqueue.c:118 [inline] > mqueue_evict_inode+0x137/0x9c0 ipc/mqueue.c:402 > evict+0x481/0x920 fs/inode.c:552 > iput_final fs/inode.c:1514 [inline] > iput+0x7b9/0xaf0 fs/inode.c:1541 > dentry_unlink_inode+0x4b0/0x5e0 fs/dcache.c:376 > __dentry_kill+0x3b7/0x6d0 fs/dcache.c:573 > shrink_dentry_list+0x3c5/0xcf0 fs/dcache.c:1020 > shrink_dcache_parent+0xba/0x230 fs/dcache.c:1454 > do_one_tree+0x15/0x50 fs/dcache.c:1485 > shrink_dcache_for_umount+0xbb/0x290 fs/dcache.c:1502 > generic_shutdown_super+0xcd/0x540 fs/super.c:424 > kill_anon_super fs/super.c:987 [inline] > kill_litter_super+0x72/0x90 fs/super.c:997 > deactivate_locked_super+0x88/0xd0 fs/super.c:312 > deactivate_super+0x141/0x1b0 fs/super.c:343 > cleanup_mnt+0xb2/0x150 fs/namespace.c:1173 > __cleanup_mnt+0x16/0x20 fs/namespace.c:1180 > task_work_run+0x199/0x270 kernel/task_work.c:113 > exit_task_work include/linux/task_work.h:22 [inline] Seems we can simply fix it by swapping exit_task_work() with exit_task_namespaces() in do_exit()... > do_exit+0x9bb/0x1ae0 kernel/exit.c:869 > do_group_exit+0x149/0x400 kernel/exit.c:972 > SYSC_exit_group kernel/exit.c:983 [inline] > SyS_exit_group+0x1d/0x20 kernel/exit.c:981 > entry_SYSCALL_64_fastpath+0x1f/0x96 > RIP: 0033:0x440729 > RSP: 002b:00007ffd090ef228 EFLAGS: 00000206 ORIG_RAX: 00000000000000e7 > RAX: ffffffffffffffda RBX: 0030656c69662f2e RCX: 0000000000440729 > RDX: 0000000000440729 RSI: 0000000000000000 RDI: 0000000000000001 > RBP: 00000000006cb018 R08: 0000000000000000 R09: 00000000004002c8 > R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000401bf0 > R13: 0000000000401c80 R14: 0000000000000000 R15: 0000000000000000 > > Allocated by task 3156: > 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:3614 > kmalloc include/linux/slab.h:516 [inline] > create_ipc_ns ipc/namespace.c:45 [inline] > copy_ipcs+0x1b3/0x520 ipc/namespace.c:96 > create_new_namespaces+0x278/0x880 kernel/nsproxy.c:87 > unshare_nsproxy_namespaces+0xae/0x1e0 kernel/nsproxy.c:206 > SYSC_unshare kernel/fork.c:2421 [inline] > SyS_unshare+0x653/0xfa0 kernel/fork.c:2371 > entry_SYSCALL_64_fastpath+0x1f/0x96 > > Freed by task 3156: > 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 > free_ipc_ns ipc/namespace.c:139 [inline] > put_ipc_ns+0x112/0x150 ipc/namespace.c:164 > free_nsproxy+0xc0/0x1f0 kernel/nsproxy.c:180 > switch_task_namespaces+0x9d/0xc0 kernel/nsproxy.c:229 > exit_task_namespaces+0x17/0x20 kernel/nsproxy.c:234 > do_exit+0x9b6/0x1ae0 kernel/exit.c:868 > do_group_exit+0x149/0x400 kernel/exit.c:972 > SYSC_exit_group kernel/exit.c:983 [inline] > SyS_exit_group+0x1d/0x20 kernel/exit.c:981 > entry_SYSCALL_64_fastpath+0x1f/0x96 > > The buggy address belongs to the object at ffff8801c51bb200 > which belongs to the cache kmalloc-2048 of size 2048 > The buggy address is located 0 bytes inside of > 2048-byte region [ffff8801c51bb200, ffff8801c51bba00) > The buggy address belongs to the page: > page:000000007764ba6d count:1 mapcount:0 mapping:000000002c36623f index:0x0 > compound_mapcount: 0 > flags: 0x2fffc0000008100(slab|head) > raw: 02fffc0000008100 ffff8801c51ba100 0000000000000000 0000000100000003 > raw: ffffea000715d320 ffff8801dac01950 ffff8801dac00c40 0000000000000000 > page dumped because: kasan: bad access detected > > Memory state around the buggy address: > ffff8801c51bb100: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc > ffff8801c51bb180: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >> >> ffff8801c51bb200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > > ^ > ffff8801c51bb280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ffff8801c51bb300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb > ================================================================== > -- To unsubscribe from this list: send the line "unsubscribe linux-sctp" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
