On Fri, Dec 8, 2017 at 4:16 PM, syzbot <bot+ed0838d0fa4c4f2b528e20286e6dc63effc7c14d@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote: > syzkaller has found reproducer for the following crash on > 82bcf1def3b5f1251177ad47c44f7e17af039b4b > git://git.cmpxchg.org/linux-mmots.git/master > compiler: gcc (GCC) 7.1.1 20170620 > .config is attached > Raw console output is attached. > > syzkaller reproducer is attached. See https://goo.gl/kgGztJ > for information about syzkaller reproducers > > > skbuff: skb_over_panic: text:0000000010b86b8d len:196 put:20 > head:000000003b477e60 data:000000000e85441e tail:0xd4 end:0xc0 dev:lo > ------------[ cut here ]------------ > kernel BUG at net/core/skbuff.c:104! > invalid opcode: 0000 [#1] SMP KASAN > Dumping ftrace buffer: > (ftrace buffer empty) > Modules linked in: > CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.15.0-rc2-mm1+ #39 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS > Google 01/01/2011 > RIP: 0010:skb_panic+0x15c/0x1f0 net/core/skbuff.c:100 > RSP: 0018:ffff8801db307508 EFLAGS: 00010286 > RAX: 0000000000000082 RBX: ffff8801c517e840 RCX: 0000000000000000 > RDX: 0000000000000082 RSI: 1ffff1003b660e61 RDI: ffffed003b660e95 > RBP: ffff8801db307570 R08: 1ffff1003b660e23 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000000 R12: ffffffff85bd4020 > R13: ffffffff84754ed2 R14: 0000000000000014 R15: ffff8801c4e26540 > FS: 0000000000000000(0000) GS:ffff8801db300000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 0000000000463610 CR3: 00000001c6698000 CR4: 00000000001406e0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > Call Trace: > <IRQ> > skb_over_panic net/core/skbuff.c:109 [inline] > skb_put+0x181/0x1c0 net/core/skbuff.c:1694 > add_grhead.isra.24+0x42/0x3b0 net/ipv6/mcast.c:1695 > add_grec+0xa55/0x1060 net/ipv6/mcast.c:1817 > mld_send_cr net/ipv6/mcast.c:1903 [inline] > mld_ifc_timer_expire+0x4d2/0x770 net/ipv6/mcast.c:2448 > call_timer_fn+0x23b/0x840 kernel/time/timer.c:1320 > expire_timers kernel/time/timer.c:1357 [inline] > __run_timers+0x7e1/0xb60 kernel/time/timer.c:1660 > run_timer_softirq+0x4c/0xb0 kernel/time/timer.c:1686 > __do_softirq+0x29d/0xbb2 kernel/softirq.c:285 > invoke_softirq kernel/softirq.c:365 [inline] > irq_exit+0x1d3/0x210 kernel/softirq.c:405 > exiting_irq arch/x86/include/asm/apic.h:540 [inline] > smp_apic_timer_interrupt+0x16b/0x700 arch/x86/kernel/apic/apic.c:1052 > apic_timer_interrupt+0xa9/0xb0 arch/x86/entry/entry_64.S:920 > </IRQ> > RIP: 0010:native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:54 > RSP: 0018:ffff8801d9f97da8 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff11 > RAX: dffffc0000000000 RBX: 1ffff1003b3f2fb8 RCX: 0000000000000000 > RDX: 1ffffffff0c59734 RSI: 0000000000000001 RDI: ffffffff862cb9a0 > RBP: ffff8801d9f97da8 R08: 0000000000000000 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000001 > R13: ffff8801d9f97e60 R14: ffffffff869eb920 R15: 0000000000000000 > arch_safe_halt arch/x86/include/asm/paravirt.h:93 [inline] > default_idle+0xbf/0x430 arch/x86/kernel/process.c:355 > arch_cpu_idle+0xa/0x10 arch/x86/kernel/process.c:346 > default_idle_call+0x36/0x90 kernel/sched/idle.c:98 > cpuidle_idle_call kernel/sched/idle.c:156 [inline] > do_idle+0x24a/0x3b0 kernel/sched/idle.c:246 > cpu_startup_entry+0x18/0x20 kernel/sched/idle.c:351 > start_secondary+0x330/0x460 arch/x86/kernel/smpboot.c:277 > secondary_startup_64+0xa5/0xb0 arch/x86/kernel/head_64.S:237 > Code: 03 0f b6 04 01 84 c0 74 04 3c 03 7e 20 8b 4b 78 41 57 48 c7 c7 a0 38 > bd 85 52 56 4c 89 ea 41 50 4c 89 e6 45 89 f0 e8 0c b6 3d fd <0f> 0b 4c 89 4d > b8 4c 89 45 c0 48 89 75 c8 48 89 55 d0 e8 7d 93 > RIP: skb_panic+0x15c/0x1f0 net/core/skbuff.c:100 RSP: ffff8801db307508 > ---[ end trace 941a8a0f633e271f ]--- > This isn't a sctp problem, but mld's, seems when lo's mtu became 0, it allocs a skb without enough space in add_grec(): if (AVAILABLE(skb) < sizeof(*psrc) + first*sizeof(struct mld2_grec)) { if (truncate && !first) break; /* truncate these */ if (pgr) pgr->grec_nsrcs = htons(scount); if (skb) mld_sendpack(skb); skb = mld_newpack(idev, dev->mtu); <--- I will check this for sure later on both igmp and mld. -- To unsubscribe from this list: send the line "unsubscribe linux-sctp" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
