bisecting fixing commit since 325d0eab4f31c6240b59d5b2b8042c88f59405b5 building syzkaller on 9564d2e9821aea842b6ab213174aabd4b578b039 testing commit 325d0eab4f31c6240b59d5b2b8042c88f59405b5 with gcc (GCC) 8.1.0 kernel signature: 992deac40441aef6bbae63f88c4e9cb41c6745ee3d99af2e3239909267b10e66 all runs: crashed: BUG: unable to handle kernel NULL pointer dereference in skb_release_data testing current HEAD 6ee1d745b7c9fd573fba142a2efdad76a9f1cb04 testing commit 6ee1d745b7c9fd573fba142a2efdad76a9f1cb04 with gcc (GCC) 8.1.0 kernel signature: 954e11d5683608c4d3502e967e2345d554735ab82ed0b4806fe18367b996f890 all runs: crashed: WARNING in skb_warn_bad_offload revisions tested: 2, total time: 17m6.313520963s (build: 10m10.84762838s, test: 6m12.885428215s) the crash still happens on HEAD commit msg: Linux 5.11-rc5 crash: WARNING in skb_warn_bad_offload hash(0x0 sw=0 l4=0) proto=0x88f5 pkttype=0 iif=0 dev name=gtp2 feat=0x0x0000000000005000 skb linear: 00000000: 00 01 02 00 01 00 00 24 00 00 00 00 ------------[ cut here ]------------ gtp2: caps=(0x0000000000005000, 0x0000000000000000) WARNING: CPU: 1 PID: 3580 at net/core/dev.c:3199 skb_warn_bad_offload+0x6d/0xd0 net/core/dev.c:3197 Modules linked in: CPU: 1 PID: 3580 Comm: systemd-udevd Not tainted 5.11.0-rc5-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:skb_warn_bad_offload+0x6d/0xd0 net/core/dev.c:3197 Code: 8d 93 c8 00 00 00 48 8d 88 70 03 00 00 48 85 c0 48 c7 c0 38 e4 d5 83 48 0f 44 c8 4c 89 e6 48 c7 c7 1e 35 55 84 e8 3f 13 89 00 <0f> 0b 5b 5d 41 5c c3 80 3b 00 49 c7 c4 2c 06 40 84 74 ad be 25 00 RSP: 0018:ffffc900000ccd70 EFLAGS: 00010282 RAX: 0000000000000000 RBX: ffff888117264000 RCX: 0000000000000301 RDX: 0000000000000301 RSI: ffffffff8450d80e RDI: 00000000ffffffff RBP: ffff88810b60cc00 R08: 0000000000000001 R09: 0000000000000001 R10: 0000000000000001 R11: 0000000000000001 R12: ffff888117264000 R13: ffffc900000cce0b R14: 0000000000000000 R15: ffff88810b60cc00 FS: 00007f45f4bd08c0(0000) GS:ffff888237d00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fffc20bdfc0 CR3: 00000001092ec005 CR4: 00000000001706e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: gso_features_check net/core/dev.c:3504 [inline] netif_skb_features+0x233/0x290 net/core/dev.c:3537 validate_xmit_skb+0x1c/0x310 net/core/dev.c:3632 __dev_queue_xmit+0x814/0xd90 net/core/dev.c:4142 mrp_queue_xmit net/802/mrp.c:351 [inline] mrp_join_timer+0x48/0x70 net/802/mrp.c:595 call_timer_fn+0xa5/0x340 kernel/time/timer.c:1417 expire_timers kernel/time/timer.c:1462 [inline] __run_timers kernel/time/timer.c:1731 [inline] run_timer_softirq+0x233/0x5f0 kernel/time/timer.c:1744 __do_softirq+0xf6/0x5e8 kernel/softirq.c:343 asm_call_irq_on_stack+0xf/0x20 __run_on_irqstack arch/x86/include/asm/irq_stack.h:26 [inline] run_on_irqstack_cond arch/x86/include/asm/irq_stack.h:77 [inline] do_softirq_own_stack+0x7c/0xa0 arch/x86/kernel/irq_64.c:77 invoke_softirq kernel/softirq.c:226 [inline] __irq_exit_rcu kernel/softirq.c:420 [inline] irq_exit_rcu+0xfa/0x120 kernel/softirq.c:432 sysvec_apic_timer_interrupt+0x57/0xf0 arch/x86/kernel/apic/apic.c:1096 asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:628 RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:653 [inline] RIP: 0010:seqcount_lockdep_reader_access include/linux/seqlock.h:105 [inline] RIP: 0010:set_root+0xb1/0x1c0 fs/namei.c:852 Code: 00 00 4c 89 e7 e8 5f f5 dc ff 48 8b 75 08 4c 89 e7 e8 33 f2 dc ff 48 83 3d 43 08 46 03 00 58 0f 84 b1 00 00 00 4c 89 f7 57 9d <0f> 1f 44 00 00 41 8b 45 48 a8 01 74 0a f3 90 41 8b 45 48 a8 01 75 RSP: 0018:ffffc900001cfca8 EFLAGS: 00000282 RAX: 00000000001c88d7 RBX: ffffc900001cfdc0 RCX: ffffc900001cfc64 RDX: ffffffff81493a90 RSI: ffffffff843bd97b RDI: 0000000000000282 RBP: ffffc900001cfcd0 R08: 0000000000000001 R09: 0000000000000001 R10: 0000000000000001 R11: 0000000000000000 R12: ffff88810096c590 R13: ffff88810096c540 R14: 0000000000000282 R15: 0000000000000000 nd_jump_root+0xb0/0xe0 fs/namei.c:873 path_init+0x4f2/0x660 fs/namei.c:2246 path_openat+0x90/0xac0 fs/namei.c:3366 do_filp_open+0x8e/0x100 fs/namei.c:3398 do_sys_openat2+0x229/0x2e0 fs/open.c:1172 do_sys_open+0x46/0x80 fs/open.c:1188 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x7f45f3d17840 Code: 73 01 c3 48 8b 0d 68 77 20 00 f7 d8 64 89 01 48 83 c8 ff c3 66 0f 1f 44 00 00 83 3d 89 bb 20 00 00 75 10 b8 02 00 00 00 0f 05 <48> 3d 01 f0 ff ff 73 31 c3 48 83 ec 08 e8 1e f6 ff ff 48 89 04 24 RSP: 002b:00007fffc20c0468 EFLAGS: 00000246 ORIG_RAX: 0000000000000002 RAX: ffffffffffffffda RBX: 00000000ffffffff RCX: 00007f45f3d17840 RDX: 00000000000001a4 RSI: 0000000000080141 RDI: 000055dcac9d4369 RBP: 000055dcac9d4369 R08: eec0feff00000000 R09: 0000000000000007 R10: 78d9db6bc8b618ea R11: 0000000000000246 R12: 000055dcacd65a60 R13: 00000000fffffffe R14: 0000000000000000 R15: 00007fffc20c0540