Hello, I'm running the syzkaller fuzzer for v4.10-rc4 (0aa0313f9d576affd7747cc3f179feb097d28990) and have such a crash in sctp code: [ 38.423932] ------------[ cut here ]------------ [ 38.424298] kernel BUG at net/sctp/socket.c:7425! [ 38.424583] invalid opcode: 0000 [#1] SMP KASAN [ 38.424839] Dumping ftrace buffer: [ 38.425031] (ftrace buffer empty) [ 38.425232] Modules linked in: sctp libcrc32c snd_hda_codec_generic snd_hda_intel snd_hda_codec snd_hda_core snd_intel8x0 snd_ens1370 snd_ac97_codec gameport snd_rawmidi snd_hwdep snd_seq_device ac97_bus snd_pcm hid_generic joydev usbmouse snd_timer psmouse usbhid e1000 snd hid parport_pc i2c_piix4 soundcore serio_raw parport input_leds pcspkr floppy evbug mac_hid [ 38.427058] CPU: 0 PID: 1930 Comm: syz-executor12 Not tainted 4.10.0-rc4+ #2 [ 38.427457] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Ubuntu-1.8.2-1ubuntu1 04/01/2014 [ 38.427999] task: ffff88006945ca00 task.stack: ffff880053e40000 [ 38.428364] RIP: 0010:sctp_sendmsg+0x29b3/0x3030 [sctp] [ 38.428719] RSP: 0018:ffff880053e478f8 EFLAGS: 00010297 [ 38.429062] RAX: ffff88006945ca00 RBX: ffff880048d148c0 RCX: 0000000000000000 [ 38.429636] RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff88006d022c88 [ 38.430051] RBP: ffff880053e47b70 R08: 0000000000000560 R09: ffff88007ffda680 [ 38.430473] R10: 000000000000000a R11: 1ffffd400032be05 R12: dffffc0000000000 [ 38.430915] R13: ffff880048d148c0 R14: 0000000000000000 R15: ffff880059ad9160 [ 38.431390] FS: 00007f984a645700(0000) GS:ffff88006d000000(0000) knlGS:0000000000000000 [ 38.431979] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 38.432405] CR2: 0000000020005fe0 CR3: 000000006400a000 CR4: 00000000000006f0 [ 38.432827] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 38.433253] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 38.433765] Call Trace: [ 38.433938] ? sctp_id2assoc+0x330/0x330 [sctp] [ 38.434245] ? wake_atomic_t_function+0x2b0/0x2b0 [ 38.434545] inet_sendmsg+0x128/0x3a0 [ 38.434758] ? inet_recvmsg+0x420/0x420 [ 38.434983] sock_sendmsg+0xcf/0x110 [ 38.435192] sock_write_iter+0x222/0x3c0 [ 38.435421] ? sock_sendmsg+0x110/0x110 [ 38.435644] ? iov_iter_init+0xaf/0x1d0 [ 38.435867] __vfs_write+0x3cb/0x640 [ 38.436075] ? do_iter_readv_writev+0x4c0/0x4c0 [ 38.436338] ? apparmor_file_permission+0x27/0x30 [ 38.436618] ? rw_verify_area+0xea/0x2b0 [ 38.436853] vfs_write+0x175/0x4e0 [ 38.437053] SyS_write+0xd8/0x1b0 [ 38.437283] ? SyS_read+0x1b0/0x1b0 [ 38.437522] entry_SYSCALL_64_fastpath+0x1e/0xad [ 38.437820] RIP: 0033:0x44f869 [ 38.438013] RSP: 002b:00007f984a644b58 EFLAGS: 00000212 ORIG_RAX: 0000000000000001 [ 38.438464] RAX: ffffffffffffffda RBX: 00007f984a645700 RCX: 000000000044f869 [ 38.438886] RDX: 0000000000000018 RSI: 0000000020ac4fe8 RDI: 0000000000000004 [ 38.439305] RBP: 00007ffe1d7be490 R08: 0000000000000000 R09: 0000000000000000 [ 38.439712] R10: 0000000000000000 R11: 0000000000000212 R12: 0000000000000000 [ 38.440145] R13: 00007ffe1d7be40f R14: 00007f984a6459c0 R15: 0000000000000000 [ 38.440563] Code: c7 c7 10 1a 5c a0 e8 4d fb 76 e1 c6 44 24 68 01 e9 a2 f2 ff ff e8 be 34 e1 e0 8b 9c 24 98 00 00 00 e9 06 fd ff ff e8 ad 34 e1 e0 <0f> 0b e8 a6 34 e1 e0 4c 8b 4c 24 78 4c 8b 44 24 68 4c 89 f9 48 [ 38.441881] RIP: sctp_sendmsg+0x29b3/0x3030 [sctp] RSP: ffff880053e478f8 [ 38.442341] ---[ end trace c704b04c884389c0 ]--- [ 38.442634] Kernel panic - not syncing: Fatal exception [ 38.443084] Dumping ftrace buffer: [ 38.443335] (ftrace buffer empty) [ 38.443590] Kernel Offset: disabled Unfortunately, I didn't manage to get a C program reproducing the crash (looks like race). However, I stably hit it on my setup - so I can help fixing the issue. The crash happens here: /* Let another process have a go. Since we are going * to sleep anyway. */ release_sock(sk); current_timeo = schedule_timeout(current_timeo); > BUG_ON(sk != asoc->base.sk); lock_sock(sk); I've added some debugging output and see, that the original value of asoc->base.sk is changed to the address of another struct sock, which appeared in sctp_endpoint_init() shortly before the crash. Hope for some assistance. Best regards, Alexander -- 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
