bisecting fixing commit since 8034e99d1a010a795b979582c0b2370584d8abf4 building syzkaller on 8b9ca619df135211a89cc19719f2705d0016045d testing commit 8034e99d1a010a795b979582c0b2370584d8abf4 compiler: gcc version 8.4.1 20210217 (GCC) kernel signature: 86f829d26708ef5704833d90a45d12c99dafe78c729721a6fcfc3f9be2c038f0 run #0: crashed: unregister_netdevice: waiting for DEV to become free run #1: crashed: unregister_netdevice: waiting for DEV to become free run #2: crashed: unregister_netdevice: waiting for DEV to become free run #3: crashed: unregister_netdevice: waiting for DEV to become free run #4: crashed: unregister_netdevice: waiting for DEV to become free run #5: crashed: unregister_netdevice: waiting for DEV to become free run #6: crashed: KASAN: use-after-free Read in udf_get_fileident run #7: crashed: unregister_netdevice: waiting for DEV to become free run #8: crashed: unregister_netdevice: waiting for DEV to become free run #9: crashed: unregister_netdevice: waiting for DEV to become free run #10: crashed: unregister_netdevice: waiting for DEV to become free run #11: crashed: unregister_netdevice: waiting for DEV to become free run #12: crashed: unregister_netdevice: waiting for DEV to become free run #13: crashed: unregister_netdevice: waiting for DEV to become free run #14: crashed: unregister_netdevice: waiting for DEV to become free run #15: crashed: unregister_netdevice: waiting for DEV to become free run #16: crashed: unregister_netdevice: waiting for DEV to become free run #17: crashed: unregister_netdevice: waiting for DEV to become free run #18: crashed: unregister_netdevice: waiting for DEV to become free run #19: crashed: unregister_netdevice: waiting for DEV to become free testing current HEAD 74766a973637a02c32c04c1c6496e114e4855239 testing commit 74766a973637a02c32c04c1c6496e114e4855239 compiler: gcc version 8.4.1 20210217 (GCC) kernel signature: 18334f4a0ddf6d4092518d8f62e50b5da982260cc2f05e05ff45aeba81ad918c all runs: crashed: unregister_netdevice: waiting for DEV to become free revisions tested: 2, total time: 21m1.157662485s (build: 14m32.433836897s, test: 6m7.084763141s) the crash still happens on HEAD commit msg: Linux 4.14.275 crash: unregister_netdevice: waiting for DEV to become free IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_batadv: link becomes ready IPv6: ADDRCONF(NETDEV_CHANGE): bond0: link becomes ready can: request_module (can-proto-0) failed. can: request_module (can-proto-0) failed. can: request_module (can-proto-0) failed. unregister_netdevice: waiting for ip6gre0 to become free. Usage count = -1 UDF-fs: INFO Mounting volume 'LinuxUDF', timestamp 2020/09/19 18:44 (1000) ================================================================== BUG: KASAN: slab-out-of-bounds in udf_get_fileident+0x1d1/0x1f0 fs/udf/directory.c:178 Read of size 2 at addr ffff8880aa421f3c by task syz-executor859/8307 CPU: 0 PID: 8307 Comm: syz-executor859 Not tainted 4.14.275-syzkaller #0 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+0x14b/0x1e7 lib/dump_stack.c:58 print_address_description.cold.6+0x9/0x1ca mm/kasan/report.c:252 kasan_report_error mm/kasan/report.c:351 [inline] kasan_report mm/kasan/report.c:409 [inline] kasan_report.cold.7+0x11a/0x2d3 mm/kasan/report.c:393 __asan_report_load_n_noabort+0xf/0x20 mm/kasan/report.c:440 udf_get_fileident+0x1d1/0x1f0 fs/udf/directory.c:178 udf_fileident_read+0x4b8/0x1ae0 fs/udf/directory.c:36 udf_readdir+0x5ca/0x12b0 fs/udf/dir.c:129 iterate_dir+0x188/0x660 fs/readdir.c:52 SYSC_getdents64 fs/readdir.c:358 [inline] SyS_getdents64+0x10d/0x1c0 fs/readdir.c:339 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb RIP: 0033:0x7f7193a43599 RSP: 002b:00007fff91f6fa58 EFLAGS: 00000246 ORIG_RAX: 00000000000000d9 RAX: ffffffffffffffda RBX: 0030656c69662f2e RCX: 00007f7193a43599 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000004 RBP: 00007f7193a02d90 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00007f7193a02e20 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 Allocated by task 4761: save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59 save_stack mm/kasan/kasan.c:447 [inline] set_track mm/kasan/kasan.c:459 [inline] kasan_kmalloc.part.1+0x62/0xf0 mm/kasan/kasan.c:551 kasan_kmalloc+0xaf/0xc0 mm/kasan/kasan.c:536 kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:489 kmem_cache_alloc+0x12e/0x3e0 mm/slab.c:3552 shmem_alloc_inode+0x15/0x30 mm/shmem.c:3904 alloc_inode+0x56/0x150 fs/inode.c:210 new_inode_pseudo+0xc/0xd0 fs/inode.c:899 new_inode+0x14/0x30 fs/inode.c:928 shmem_get_inode+0x6c/0x770 mm/shmem.c:2181 shmem_mknod+0x49/0x1a0 mm/shmem.c:3052 shmem_create+0x13/0x20 mm/shmem.c:3112 lookup_open+0x744/0x1c10 fs/namei.c:3241 do_last fs/namei.c:3334 [inline] path_openat+0xe81/0x2760 fs/namei.c:3569 do_filp_open+0x16b/0x220 fs/namei.c:3603 do_sys_open+0x1d0/0x350 fs/open.c:1081 SYSC_open fs/open.c:1099 [inline] SyS_open+0x19/0x20 fs/open.c:1094 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb Freed by task 0: (stack is not available) The buggy address belongs to the object at ffff8880aa421a70 which belongs to the cache shmem_inode_cache of size 1208 The buggy address is located 20 bytes to the right of 1208-byte region [ffff8880aa421a70, ffff8880aa421f28) The buggy address belongs to the page: page:ffffea0002a90840 count:1 mapcount:0 mapping:ffff8880aa421000 index:0xffff8880aa421ffd flags: 0xfff00000000100(slab) raw: 00fff00000000100 ffff8880aa421000 ffff8880aa421ffd 0000000100000003 raw: ffffea0002872fa0 ffffea000296b5a0 ffff8880b61616c0 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8880aa421e00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ffff8880aa421e80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >ffff8880aa421f00: 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc ^ ffff8880aa421f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff8880aa422000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ==================================================================