bisecting fixing commit since 5b7a52cd2eef952cee8a72512ef370bcdef46636 building syzkaller on f24824d3d54060a7d878eeb35c47f85dab84966a testing commit 5b7a52cd2eef952cee8a72512ef370bcdef46636 with gcc (GCC) 8.4.1 20210217 kernel signature: 5433a273f5626884a166c7df515b0b970b409dca5065ab6b1c1facfdecd2ff4c run #0: crashed: general protection fault in __tcf_idr_release run #1: crashed: general protection fault in __tcf_idr_release run #2: crashed: general protection fault in __tcf_idr_release run #3: crashed: general protection fault in __tcf_idr_release run #4: crashed: general protection fault in __tcf_idr_release run #5: crashed: general protection fault in __tcf_idr_release run #6: crashed: general protection fault in __tcf_idr_release run #7: crashed: general protection fault in __tcf_idr_release run #8: crashed: BUG: unable to handle kernel paging request in tcf_action_destroy run #9: crashed: general protection fault in __tcf_idr_release run #10: crashed: BUG: unable to handle kernel paging request in tcf_action_destroy run #11: crashed: general protection fault in __tcf_idr_release run #12: crashed: general protection fault in __tcf_idr_release run #13: crashed: general protection fault in __tcf_idr_release run #14: crashed: KASAN: use-after-free Read in tcf_action_destroy run #15: crashed: general protection fault in __tcf_idr_release run #16: crashed: general protection fault in __tcf_idr_release run #17: crashed: general protection fault in __tcf_idr_release run #18: crashed: general protection fault in __tcf_idr_release run #19: crashed: general protection fault in __tcf_idr_release testing current HEAD 3242aa3a635c0958671ee1e4b0958dcc7c4e5c79 testing commit 3242aa3a635c0958671ee1e4b0958dcc7c4e5c79 with gcc (GCC) 8.4.1 20210217 kernel signature: 4f111342d9669dd3318d6e6f5446f57da75a908ce42cd6eb8b891d1cfaa2dd7c run #0: crashed: general protection fault in __tcf_idr_release run #1: crashed: general protection fault in __tcf_idr_release run #2: crashed: general protection fault in __tcf_idr_release run #3: crashed: general protection fault in __tcf_idr_release run #4: crashed: general protection fault in __tcf_idr_release run #5: crashed: general protection fault in __tcf_idr_release run #6: crashed: general protection fault in __tcf_idr_release run #7: crashed: BUG: unable to handle kernel paging request in tcf_action_destroy run #8: crashed: KASAN: use-after-free Read in tcf_action_destroy run #9: crashed: KASAN: stack-out-of-bounds Read in tcf_action_destroy revisions tested: 2, total time: 22m5.763807725s (build: 14m20.49961493s, test: 6m51.059839285s) the crash still happens on HEAD commit msg: Linux 4.14.222 crash: KASAN: stack-out-of-bounds Read in tcf_action_destroy netlink: 32 bytes leftover after parsing attributes in process `syz-executor.4'. netlink: 32 bytes leftover after parsing attributes in process `syz-executor.2'. netlink: 32 bytes leftover after parsing attributes in process `syz-executor.3'. ================================================================== BUG: KASAN: stack-out-of-bounds in tcf_action_destroy+0x115/0x160 net/sched/act_api.c:525 Read of size 8 at addr ffff8881dc78f688 by task syz-executor.5/12530 CPU: 0 PID: 12530 Comm: syz-executor.5 Not tainted 4.14.222-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 tcf_action_destroy+0x115/0x160 net/sched/act_api.c:525 tcf_action_init+0x335/0x460 net/sched/act_api.c:769 tcf_action_add net/sched/act_api.c:1079 [inline] tc_ctl_action+0x3c4/0x580 net/sched/act_api.c:1131 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 ___sys_sendmsg+0x625/0x920 net/socket.c:2062 __sys_sendmsg+0xc1/0x140 net/socket.c:2096 SYSC_sendmsg net/socket.c:2107 [inline] SyS_sendmsg+0xd/0x20 net/socket.c:2103 do_syscall_64+0x1c7/0x5b0 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb RIP: 0033:0x465889 RSP: 002b:00007fc14e58b188 EFLAGS: 00000246 ORIG_RAX: 000000000000002e RAX: ffffffffffffffda RBX: 000000000055bf00 RCX: 0000000000465889 RDX: 0000000000000000 RSI: 0000000020002980 RDI: 0000000000000003 RBP: 00000000004af68d R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000055bf00 R13: 00007ffc03ef4cff R14: 00007fc14e58b300 R15: 0000000000022000 The buggy address belongs to the page: page:ffffea000771e3c0 count:0 mapcount:0 mapping: (null) index:0x0 flags: 0x17ff00000000000() raw: 017ff00000000000 0000000000000000 0000000000000000 00000000ffffffff raw: 0000000000000000 0000000100000001 0000000000000000 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8881dc78f580: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ffff8881dc78f600: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff >ffff8881dc78f680: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ^ ffff8881dc78f700: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ffff8881dc78f780: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ==================================================================