bisecting fixing commit since 13d2ce42de8cb98ff952f8de6307f896203854c2 building syzkaller on 8f160dd5d603e9cd86705baad260794afa3e5cb3 testing commit 13d2ce42de8cb98ff952f8de6307f896203854c2 compiler: gcc version 8.4.1 20210217 (GCC) kernel signature: 17b859030d45d14eb2cdf82ee86ef88f8d038f8a196afb964004ba3f2004a7c3 run #0: crashed: KASAN: use-after-free Read in ipvlan_queue_xmit run #1: crashed: KASAN: use-after-free Read in ipvlan_queue_xmit run #2: crashed: KASAN: use-after-free Read in ipvlan_queue_xmit run #3: crashed: KASAN: slab-out-of-bounds Read in ipvlan_queue_xmit run #4: crashed: KASAN: slab-out-of-bounds Read in ipvlan_queue_xmit run #5: crashed: KASAN: use-after-free Read in ipvlan_queue_xmit run #6: crashed: KASAN: slab-out-of-bounds Read in ipvlan_queue_xmit run #7: crashed: KASAN: use-after-free Read in ipvlan_queue_xmit run #8: crashed: KASAN: slab-out-of-bounds Read in ipvlan_queue_xmit run #9: crashed: KASAN: use-after-free Read in ipvlan_queue_xmit run #10: crashed: KASAN: slab-out-of-bounds Read in ipvlan_queue_xmit run #11: crashed: KASAN: slab-out-of-bounds Read in ipvlan_queue_xmit run #12: crashed: KASAN: slab-out-of-bounds Read in ipvlan_queue_xmit run #13: crashed: KASAN: slab-out-of-bounds Read in ipvlan_queue_xmit run #14: crashed: KASAN: use-after-free Read in ipvlan_queue_xmit run #15: crashed: KASAN: slab-out-of-bounds Read in ipvlan_queue_xmit run #16: crashed: KASAN: slab-out-of-bounds Read in ipvlan_queue_xmit run #17: crashed: KASAN: use-after-free Read in ipvlan_queue_xmit run #18: crashed: KASAN: slab-out-of-bounds Read in ipvlan_queue_xmit run #19: crashed: KASAN: use-after-free Read in ipvlan_queue_xmit testing current HEAD 4938296e03bd227e5020d63d418956fe52baf97c testing commit 4938296e03bd227e5020d63d418956fe52baf97c compiler: gcc version 8.4.1 20210217 (GCC) kernel signature: a11778c41313d4a9aacbb0307775941fb3b77a0be746ef07ff7ee8b089b1e686 run #0: crashed: KASAN: use-after-free Read in ipvlan_queue_xmit run #1: crashed: KASAN: slab-out-of-bounds Read in ipvlan_queue_xmit run #2: crashed: KASAN: slab-out-of-bounds Read in ipvlan_queue_xmit run #3: crashed: KASAN: use-after-free Read in ipvlan_queue_xmit run #4: crashed: KASAN: slab-out-of-bounds Read in ipvlan_queue_xmit run #5: crashed: KASAN: use-after-free Read in ipvlan_queue_xmit run #6: crashed: KASAN: slab-out-of-bounds Read in ipvlan_queue_xmit run #7: crashed: KASAN: use-after-free Read in ipvlan_queue_xmit run #8: crashed: KASAN: slab-out-of-bounds Read in ipvlan_queue_xmit run #9: crashed: KASAN: slab-out-of-bounds Read in ipvlan_queue_xmit revisions tested: 2, total time: 25m20.488807128s (build: 18m10.365757572s, test: 6m44.59976342s) the crash still happens on HEAD commit msg: Linux 4.19.198 crash: KASAN: slab-out-of-bounds Read in ipvlan_queue_xmit IPv6: ADDRCONF(NETDEV_UP): wlan1: link is not ready batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3d) already exists on: batadv_slave_0 ================================================================== BUG: KASAN: slab-out-of-bounds in ipvlan_process_outbound drivers/net/ipvlan/ipvlan_core.c:533 [inline] BUG: KASAN: slab-out-of-bounds in ipvlan_xmit_mode_l3 drivers/net/ipvlan/ipvlan_core.c:593 [inline] BUG: KASAN: slab-out-of-bounds in ipvlan_queue_xmit+0x89d/0x1630 drivers/net/ipvlan/ipvlan_core.c:654 Read of size 4 at addr ffff8880990687ff by task syz-executor.3/9837 batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems! CPU: 1 PID: 9837 Comm: syz-executor.3 Not tainted 4.19.198-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x17c/0x226 lib/dump_stack.c:118 print_address_description.cold.6+0x9/0x211 mm/kasan/report.c:256 kasan_report_error mm/kasan/report.c:354 [inline] kasan_report mm/kasan/report.c:412 [inline] kasan_report.cold.7+0x242/0x2fe mm/kasan/report.c:396 __asan_report_load4_noabort+0x14/0x20 mm/kasan/report.c:432 ipvlan_process_outbound drivers/net/ipvlan/ipvlan_core.c:533 [inline] ipvlan_xmit_mode_l3 drivers/net/ipvlan/ipvlan_core.c:593 [inline] ipvlan_queue_xmit+0x89d/0x1630 drivers/net/ipvlan/ipvlan_core.c:654 ipvlan_start_xmit+0x4a/0x150 drivers/net/ipvlan/ipvlan_main.c:290 __netdev_start_xmit include/linux/netdevice.h:4345 [inline] netdev_start_xmit include/linux/netdevice.h:4359 [inline] dev_direct_xmit+0x2db/0x620 net/core/dev.c:3905 packet_direct_xmit+0xd6/0x140 net/packet/af_packet.c:246 packet_snd net/packet/af_packet.c:2988 [inline] packet_sendmsg+0x3479/0x6670 net/packet/af_packet.c:3013 batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3d) already exists on: batadv_slave_0 batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems! batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3d) already exists on: batadv_slave_0 sock_sendmsg_nosec net/socket.c:651 [inline] sock_sendmsg+0xac/0xf0 net/socket.c:661 batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems! sock_write_iter+0x215/0x420 net/socket.c:966 batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3d) already exists on: batadv_slave_0 batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems! call_write_iter include/linux/fs.h:1821 [inline] aio_write+0x2e4/0x560 fs/aio.c:1574 batman_adv: The newly added mac address (aa:aa:aa:aa:aa:3d) already exists on: batadv_slave_0 batman_adv: It is strongly recommended to keep mac addresses unique to avoid problems! IPv6: ADDRCONF(NETDEV_UP): batadv_slave_0: link is not ready batman_adv: batadv0: Interface activated: batadv_slave_0 __io_submit_one fs/aio.c:1858 [inline] io_submit_one+0x764/0x1db0 fs/aio.c:1909 IPv6: ADDRCONF(NETDEV_UP): wlan0: link is not ready __do_sys_io_submit fs/aio.c:1953 [inline] __se_sys_io_submit+0x112/0x390 fs/aio.c:1924 __x64_sys_io_submit+0x6e/0xb0 fs/aio.c:1924 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x465a49 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f269ddbb188 EFLAGS: 00000246 ORIG_RAX: 00000000000000d1 RAX: ffffffffffffffda RBX: 000000000055bf40 RCX: 0000000000465a49 RDX: 0000000020000080 RSI: 0000000000000001 RDI: 00007f269dd9a000 RBP: 00000000004af682 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000055bf40 R13: 00007ffe838b157f R14: 00007f269ddbb300 R15: 0000000000022000 Allocated by task 9782: save_stack mm/kasan/kasan.c:448 [inline] set_track mm/kasan/kasan.c:460 [inline] kasan_kmalloc.part.1+0x62/0xf0 mm/kasan/kasan.c:553 kasan_kmalloc+0xaf/0xc0 mm/kasan/kasan.c:538 kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:490 kmem_cache_alloc+0x12e/0x390 mm/slab.c:3559 getname_flags+0xb8/0x510 fs/namei.c:140 user_path_at_empty+0x1e/0x40 fs/namei.c:2609 user_path_at include/linux/namei.h:57 [inline] vfs_statx+0xbe/0x150 fs/stat.c:185 vfs_stat include/linux/fs.h:3132 [inline] __do_sys_newstat fs/stat.c:337 [inline] __se_sys_newstat+0x85/0xe0 fs/stat.c:333 __x64_sys_newstat+0x4f/0x70 fs/stat.c:333 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe Freed by task 9782: save_stack mm/kasan/kasan.c:448 [inline] set_track mm/kasan/kasan.c:460 [inline] __kasan_slab_free+0x13c/0x220 mm/kasan/kasan.c:521 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528 __cache_free mm/slab.c:3503 [inline] kmem_cache_free+0x83/0x290 mm/slab.c:3765 putname+0xa8/0xe0 fs/namei.c:261 filename_lookup.part.21+0x1ec/0x360 fs/namei.c:2358 filename_lookup fs/namei.c:2342 [inline] user_path_at_empty+0x39/0x40 fs/namei.c:2609 user_path_at include/linux/namei.h:57 [inline] vfs_statx+0xbe/0x150 fs/stat.c:185 vfs_stat include/linux/fs.h:3132 [inline] __do_sys_newstat fs/stat.c:337 [inline] __se_sys_newstat+0x85/0xe0 fs/stat.c:333 __x64_sys_newstat+0x4f/0x70 fs/stat.c:333 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe The buggy address belongs to the object at ffff888099068d40 which belongs to the cache names_cache of size 4096 The buggy address is located 1345 bytes to the left of 4096-byte region [ffff888099068d40, ffff888099069d40) The buggy address belongs to the page: page:ffffea0002641a00 count:1 mapcount:0 mapping:ffff88813be46080 index:0x0 compound_mapcount: 0 flags: 0xfff00000008100(slab|head) raw: 00fff00000008100 ffffea0002640588 ffffea0002641a88 ffff88813be46080 raw: 0000000000000000 ffff888099068d40 0000000100000001 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff888099068680: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff888099068700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff888099068780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ^ ffff888099068800: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff888099068880: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ==================================================================