bisecting fixing commit since 2762b48e9611529239da2e68cba908dbbec9805f building syzkaller on 63631df1539816bc62c7be40779c5f3e23b23b2f testing commit 2762b48e9611529239da2e68cba908dbbec9805f with gcc (GCC) 8.4.1 20210217 kernel signature: 3907c510389138a19af45e515142af699f8c9eb37729be48a512c2446aaaa271 run #0: crashed: KASAN: use-after-free Read in perf_output_read run #1: crashed: KASAN: use-after-free Read in perf_output_read run #2: crashed: KASAN: use-after-free Read in perf_output_read run #3: crashed: KASAN: use-after-free Read in perf_output_read run #4: crashed: KASAN: use-after-free Read in perf_output_read run #5: crashed: KASAN: use-after-free Read in perf_output_read run #6: crashed: KASAN: slab-out-of-bounds Read in perf_output_read run #7: crashed: KASAN: use-after-free Read in perf_output_read run #8: crashed: KASAN: slab-out-of-bounds Read in perf_output_read run #9: crashed: KASAN: slab-out-of-bounds Read in perf_output_read run #10: crashed: KASAN: use-after-free Read in perf_output_read run #11: crashed: KASAN: use-after-free Read in perf_output_read run #12: crashed: KASAN: use-after-free Read in perf_output_read run #13: crashed: KASAN: use-after-free Read in perf_output_read run #14: crashed: KASAN: slab-out-of-bounds Read in perf_output_read run #15: OK run #16: OK run #17: OK run #18: OK run #19: OK testing current HEAD 29c52025152bab4c557d8174da58f1a4c8e70438 testing commit 29c52025152bab4c557d8174da58f1a4c8e70438 with gcc (GCC) 8.4.1 20210217 kernel signature: b770625015da7d78ca3d1ddaedeb440c6f87f933561bcbdd4d868d396c040434 run #0: crashed: KASAN: use-after-free Read in perf_output_read run #1: crashed: KASAN: use-after-free Read in perf_output_read run #2: crashed: KASAN: use-after-free Read in perf_output_read run #3: crashed: KASAN: use-after-free Read in perf_output_read run #4: crashed: KASAN: slab-out-of-bounds Read in perf_output_read run #5: crashed: KASAN: use-after-free Read in perf_output_read run #6: crashed: KASAN: use-after-free Read in perf_output_read run #7: crashed: KASAN: use-after-free Read in perf_output_read run #8: OK run #9: OK revisions tested: 2, total time: 37m31.782163536s (build: 13m50.816143275s, test: 22m44.258039824s) the crash still happens on HEAD commit msg: Linux 4.14.221 crash: KASAN: use-after-free Read in perf_output_read ================================================================== BUG: KASAN: use-after-free in perf_output_read_group kernel/events/core.c:5895 [inline] BUG: KASAN: use-after-free in perf_output_read+0x1181/0x14f0 kernel/events/core.c:5930 Read of size 8 at addr ffff88809dbef3c8 by task syz-executor640/15164 CPU: 0 PID: 15164 Comm: syz-executor640 Not tainted 4.14.221-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_load8_noabort+0x14/0x20 mm/kasan/report.c:430 perf_output_read_group kernel/events/core.c:5895 [inline] perf_output_read+0x1181/0x14f0 kernel/events/core.c:5930 perf_output_sample+0x1276/0x1910 kernel/events/core.c:5972 __perf_event_output kernel/events/core.c:6285 [inline] perf_event_output_forward+0x103/0x1d0 kernel/events/core.c:6298 __perf_event_overflow+0x107/0x300 kernel/events/core.c:7547 perf_swevent_overflow+0x165/0x210 kernel/events/core.c:7623 perf_swevent_event+0x1f5/0x2f0 kernel/events/core.c:7656 do_perf_sw_event kernel/events/core.c:7764 [inline] ___perf_sw_event+0x26b/0x3f0 kernel/events/core.c:7795 __perf_sw_event+0x3c/0x60 kernel/events/core.c:7807 perf_sw_event include/linux/perf_event.h:1046 [inline] __do_page_fault+0x616/0xa90 arch/x86/mm/fault.c:1483 do_page_fault+0x64/0x400 arch/x86/mm/fault.c:1517 page_fault+0x25/0x50 arch/x86/entry/entry_64.S:1123 RIP: 0010:copy_user_enhanced_fast_string+0xe/0x20 arch/x86/lib/copy_user_64.S:181 RSP: 0018:ffff888092a27918 EFLAGS: 00010206 RAX: 0000000000000000 RBX: 0000000020fe1d6d RCX: 0000000000003acb RDX: 0000000000003d5e RSI: 0000000020fe2000 RDI: ffff88809f84c535 RBP: ffff888092a27940 R08: 0000000000000000 R09: 00000000000000f5 R10: ffffed1013f09fff R11: ffff88809f84ffff R12: ffff88809f84c2a2 R13: ffff88809bcc6280 R14: ffff888092a27db0 R15: ffff888092a27d60 _copy_from_iter_full+0x166/0x760 lib/iov_iter.c:608 copy_from_iter_full include/linux/uio.h:126 [inline] skb_do_copy_data_nocache include/net/sock.h:1889 [inline] skb_copy_to_page_nocache include/net/sock.h:1915 [inline] tcp_sendmsg_locked+0x193f/0x3a10 net/ipv4/tcp.c:1360 tcp_sendmsg+0x27/0x40 net/ipv4/tcp.c:1457 inet_sendmsg+0x108/0x440 net/ipv4/af_inet.c:762 sock_sendmsg_nosec net/socket.c:646 [inline] sock_sendmsg+0xac/0xf0 net/socket.c:656 SYSC_sendto net/socket.c:1763 [inline] SyS_sendto+0x1e4/0x2c0 net/socket.c:1731 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb RIP: 0033:0x452db9 RSP: 002b:00007f85b0f771f8 EFLAGS: 00000246 ORIG_RAX: 000000000000002c RAX: ffffffffffffffda RBX: 00000000004d14e8 RCX: 0000000000452db9 RDX: ffffffffffffffef RSI: 0000000020d7cfcb RDI: 0000000000000006 RBP: 00000000004d14e0 R08: 0000000000000000 R09: 0000000000000053 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000004d14ec R13: 00007ffeb2f2cacf R14: 00007f85b0f77300 R15: 0000000000022000 Allocated by task 6985: 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 __do_kmalloc_node mm/slab.c:3682 [inline] __kmalloc_node_track_caller+0x50/0x70 mm/slab.c:3696 __kmalloc_reserve.isra.7+0x2c/0xc0 net/core/skbuff.c:137 __alloc_skb+0xc1/0x540 net/core/skbuff.c:205 alloc_skb include/linux/skbuff.h:980 [inline] kobject_uevent_env+0x747/0xdf0 lib/kobject_uevent.c:479 kobject_uevent+0xb/0x10 lib/kobject_uevent.c:553 netdev_queue_add_kobject net/core/net-sysfs.c:1366 [inline] netdev_queue_update_kobjects+0x26c/0x320 net/core/net-sysfs.c:1383 register_queue_kobjects net/core/net-sysfs.c:1425 [inline] netdev_register_kobject+0x313/0x3d0 net/core/net-sysfs.c:1631 register_netdevice+0x7b5/0xe50 net/core/dev.c:7660 veth_newlink+0x3cd/0x930 drivers/net/veth.c:416 rtnl_newlink+0xca6/0x1610 net/core/rtnetlink.c:2728 rtnetlink_rcv_msg+0x34c/0x9e0 net/core/rtnetlink.c:4316 netlink_rcv_skb+0x12f/0x3b0 net/netlink/af_netlink.c:2433 rtnetlink_rcv+0x10/0x20 net/core/rtnetlink.c:4328 netlink_unicast_kernel net/netlink/af_netlink.c:1287 [inline] netlink_unicast+0x40b/0x610 net/netlink/af_netlink.c:1313 netlink_sendmsg+0x639/0xbe0 net/netlink/af_netlink.c:1878 sock_sendmsg_nosec net/socket.c:646 [inline] sock_sendmsg+0xac/0xf0 net/socket.c:656 SYSC_sendto net/socket.c:1763 [inline] SyS_sendto+0x1e4/0x2c0 net/socket.c:1731 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb Freed by task 6985: 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_slab_free+0xab/0x190 mm/kasan/kasan.c:524 __cache_free mm/slab.c:3496 [inline] kfree+0xcc/0x270 mm/slab.c:3815 skb_free_head+0x74/0x90 net/core/skbuff.c:563 skb_release_data+0x4e0/0x820 net/core/skbuff.c:583 skb_release_all+0x3d/0x50 net/core/skbuff.c:640 __kfree_skb net/core/skbuff.c:654 [inline] consume_skb+0x84/0x2a0 net/core/skbuff.c:714 netlink_broadcast_filtered+0x277/0x8c0 net/netlink/af_netlink.c:1489 kobject_uevent_env+0x887/0xdf0 lib/kobject_uevent.c:495 kobject_uevent+0xb/0x10 lib/kobject_uevent.c:553 netdev_queue_add_kobject net/core/net-sysfs.c:1366 [inline] netdev_queue_update_kobjects+0x26c/0x320 net/core/net-sysfs.c:1383 register_queue_kobjects net/core/net-sysfs.c:1425 [inline] netdev_register_kobject+0x313/0x3d0 net/core/net-sysfs.c:1631 register_netdevice+0x7b5/0xe50 net/core/dev.c:7660 veth_newlink+0x3cd/0x930 drivers/net/veth.c:416 rtnl_newlink+0xca6/0x1610 net/core/rtnetlink.c:2728 rtnetlink_rcv_msg+0x34c/0x9e0 net/core/rtnetlink.c:4316 netlink_rcv_skb+0x12f/0x3b0 net/netlink/af_netlink.c:2433 rtnetlink_rcv+0x10/0x20 net/core/rtnetlink.c:4328 netlink_unicast_kernel net/netlink/af_netlink.c:1287 [inline] netlink_unicast+0x40b/0x610 net/netlink/af_netlink.c:1313 netlink_sendmsg+0x639/0xbe0 net/netlink/af_netlink.c:1878 sock_sendmsg_nosec net/socket.c:646 [inline] sock_sendmsg+0xac/0xf0 net/socket.c:656 SYSC_sendto net/socket.c:1763 [inline] SyS_sendto+0x1e4/0x2c0 net/socket.c:1731 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb The buggy address belongs to the object at ffff88809dbef2c0 which belongs to the cache kmalloc-512 of size 512 The buggy address is located 264 bytes inside of 512-byte region [ffff88809dbef2c0, ffff88809dbef4c0) The buggy address belongs to the page: page:ffffea000276fbc0 count:1 mapcount:0 mapping:ffff88809dbef040 index:0xffff88809dbefcc0 flags: 0xfff00000000100(slab) raw: 00fff00000000100 ffff88809dbef040 ffff88809dbefcc0 0000000100000001 raw: ffffea0002acc760 ffffea00029470e0 ffff88813fe64940 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff88809dbef280: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb ffff88809dbef300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb >ffff88809dbef380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff88809dbef400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff88809dbef480: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc ==================================================================