bisecting fixing commit since 13d2ce42de8cb98ff952f8de6307f896203854c2 building syzkaller on 8f160dd5d603e9cd86705baad260794afa3e5cb3 testing commit 13d2ce42de8cb98ff952f8de6307f896203854c2 with gcc (GCC) 8.4.1 20210217 kernel signature: b8a411cc48eec9027114fd71747336dc0681a42ea20c272901bd3b051ebbab54 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: 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: use-after-free Read in ipvlan_queue_xmit run #5: crashed: KASAN: slab-out-of-bounds Read in ipvlan_queue_xmit run #6: crashed: KASAN: slab-out-of-bounds Read in ipvlan_queue_xmit run #7: crashed: KASAN: slab-out-of-bounds 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: use-after-free 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: slab-out-of-bounds Read in ipvlan_queue_xmit run #18: crashed: KASAN: slab-out-of-bounds Read in ipvlan_queue_xmit run #19: crashed: KASAN: slab-out-of-bounds Read in ipvlan_queue_xmit testing current HEAD 125222814e7b8f84df767d6ab622aff2a6d2f234 testing commit 125222814e7b8f84df767d6ab622aff2a6d2f234 with gcc (GCC) 8.4.1 20210217 kernel signature: b1069d00cda544d7eedbaa7e27ed383bf1699b0cf513c3fdaf16e34394c81411 run #0: crashed: KASAN: slab-out-of-bounds 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: use-after-free 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 revisions tested: 2, total time: 21m59.68236307s (build: 15m4.350676124s, test: 6m25.042566222s) the crash still happens on HEAD commit msg: Linux 4.19.182 crash: KASAN: use-after-free Read in ipvlan_queue_xmit IPv6: ADDRCONF(NETDEV_CHANGE): wlan1: link becomes ready wlan1: Created IBSS using preconfigured BSSID 50:50:50:50:50:50 IPv6: ADDRCONF(NETDEV_CHANGE): wlan0: link becomes ready wlan1: Creating new IBSS network, BSSID 50:50:50:50:50:50 ================================================================== BUG: KASAN: use-after-free in ipvlan_process_outbound drivers/net/ipvlan/ipvlan_core.c:533 [inline] BUG: KASAN: use-after-free in ipvlan_xmit_mode_l3 drivers/net/ipvlan/ipvlan_core.c:593 [inline] BUG: KASAN: use-after-free in ipvlan_queue_xmit+0x89d/0x1630 drivers/net/ipvlan/ipvlan_core.c:654 IPv6: ADDRCONF(NETDEV_CHANGE): wlan1: link becomes ready Read of size 4 at addr ffff88809f2cecbf by task syz-executor.2/9871 CPU: 0 PID: 9871 Comm: syz-executor.2 Not tainted 4.19.182-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 IPv6: ADDRCONF(NETDEV_UP): wlan0: link is not ready packet_direct_xmit+0xd6/0x140 net/packet/af_packet.c:246 packet_snd net/packet/af_packet.c:2988 [inline] packet_sendmsg+0x3449/0x6380 net/packet/af_packet.c:3013 wlan0: Created IBSS using preconfigured BSSID 50:50:50:50:50:50 wlan0: Creating new IBSS network, BSSID 50:50:50:50:50:50 ieee80211 phy11: Selected rate control algorithm 'minstrel_ht' IPv6: ADDRCONF(NETDEV_CHANGE): wlan0: link becomes ready sock_sendmsg_nosec net/socket.c:622 [inline] sock_sendmsg+0xac/0xf0 net/socket.c:632 sock_write_iter+0x215/0x420 net/socket.c:901 IPv6: ADDRCONF(NETDEV_UP): wlan1: link is not ready wlan1: Created IBSS using preconfigured BSSID 50:50:50:50:50:50 call_write_iter include/linux/fs.h:1821 [inline] aio_write+0x2e4/0x560 fs/aio.c:1574 wlan1: Creating new IBSS network, BSSID 50:50:50:50:50:50 __io_submit_one fs/aio.c:1858 [inline] io_submit_one+0x764/0x1db0 fs/aio.c:1909 __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:00007f2f29074188 EFLAGS: 00000246 ORIG_RAX: 00000000000000d1 RAX: ffffffffffffffda RBX: 000000000055bf40 RCX: 0000000000465a49 RDX: 0000000020000080 RSI: 0000000000000001 RDI: 00007f2f29053000 RBP: 00000000004af682 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000055bf40 R13: 00007ffee45ce78f R14: 00007f2f29074300 R15: 0000000000022000 Allocated by task 4688: 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 getname+0xd/0x10 fs/namei.c:211 do_sys_open+0x14b/0x350 fs/open.c:1079 __do_sys_open fs/open.c:1103 [inline] __se_sys_open fs/open.c:1098 [inline] __x64_sys_open+0x79/0xb0 fs/open.c:1098 do_syscall_64+0xd0/0x4e0 arch/x86/entry/common.c:293 entry_SYSCALL_64_after_hwframe+0x49/0xbe Freed by task 4688: 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 do_sys_open+0x16d/0x350 fs/open.c:1094 __do_sys_open fs/open.c:1103 [inline] __se_sys_open fs/open.c:1098 [inline] __x64_sys_open+0x79/0xb0 fs/open.c:1098 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 ffff88809f2ce440 which belongs to the cache names_cache of size 4096 The buggy address is located 2175 bytes inside of 4096-byte region [ffff88809f2ce440, ffff88809f2cf440) The buggy address belongs to the page: page:ffffea00027cb380 count:1 mapcount:0 mapping:ffff88823b845200 index:0x0 compound_mapcount: 0 flags: 0xfff00000008100(slab|head) raw: 00fff00000008100 ffffea00027cb308 ffffea00027a7e88 ffff88823b845200 raw: 0000000000000000 ffff88809f2ce440 0000000100000001 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff88809f2ceb80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88809f2cec00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff88809f2cec80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88809f2ced00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88809f2ced80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ==================================================================