Messages in this thread | | | From | Souptick Joarder <> | Date | Wed, 8 May 2019 01:00:49 +0530 | Subject | Re: general protection fault in relay_close_buf |
| |
On Tue, May 7, 2019 at 3:14 PM syzbot <syzbot+58320b7171734bf79d26@syzkaller.appspotmail.com> wrote: > > Hello, > > syzbot found the following crash on: > > HEAD commit: 371dd432 Merge branch 'for-5.1-fixes' of git://git.kernel... > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=124077dd200000 > kernel config: https://syzkaller.appspot.com/x/.config?x=856fc6d0fbbeede9 > dashboard link: https://syzkaller.appspot.com/bug?extid=58320b7171734bf79d26 > compiler: gcc (GCC) 9.0.0 20181231 (experimental) > > Unfortunately, I don't have any reproducer for this crash yet. > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > Reported-by: syzbot+58320b7171734bf79d26@syzkaller.appspotmail.com > > kasan: CONFIG_KASAN_INLINE enabled > kasan: GPF could be caused by NULL-ptr deref or user memory access > general protection fault: 0000 [#1] PREEMPT SMP KASAN > CPU: 0 PID: 6042 Comm: syz-executor.4 Not tainted 5.1.0-rc5+ #76 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS > Google 01/01/2011 > RIP: 0010:relay_close_buf+0x28/0x150 kernel/relay.c:495 > Code: 00 00 55 48 89 e5 41 54 49 89 fc 53 e8 a1 1d ff ff 49 8d bc 24 ac 00 > 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <0f> b6 14 02 48 > 89 f8 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85 dc > RSP: 0018:ffff8880976d7918 EFLAGS: 00010202 > RAX: dffffc0000000000 RBX: dffffc0000000000 RCX: ffffc9000e6c3000 > RDX: 0000000020000015 RSI: ffffffff81716f0f RDI: 00000001000000ab > RBP: ffff8880976d7928 R08: ffff88808de7a640 R09: ffffed1012edaefa > R10: ffffed1012edaef9 R11: 0000000000000003 R12: 00000000ffffffff > R13: ffff88809f86a300 R14: 0000000000000007 R15: 00000000ffffffff > FS: 00007f4e560ef700(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 0000000002540040 CR3: 00000000a158b000 CR4: 00000000001406f0 > Call Trace: > relay_open kernel/relay.c:612 [inline] > relay_open+0x619/0x980 kernel/relay.c:563 > do_blk_trace_setup+0x414/0xb90 kernel/trace/blktrace.c:532 > __blk_trace_setup+0xe3/0x190 kernel/trace/blktrace.c:577 > blk_trace_ioctl+0x170/0x300 kernel/trace/blktrace.c:716 > blkdev_ioctl+0x276/0x1d10 block/ioctl.c:591 > block_ioctl+0xee/0x130 fs/block_dev.c:1933 > vfs_ioctl fs/ioctl.c:46 [inline] > file_ioctl fs/ioctl.c:509 [inline] > do_vfs_ioctl+0xd6e/0x1390 fs/ioctl.c:696 > ksys_ioctl+0xab/0xd0 fs/ioctl.c:713 > __do_sys_ioctl fs/ioctl.c:720 [inline] > __se_sys_ioctl fs/ioctl.c:718 [inline] > __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:718 > do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290 > entry_SYSCALL_64_after_hwframe+0x49/0xbe > RIP: 0033:0x458c29 > Code: ad b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 > 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff > ff 0f 83 7b b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00 > RSP: 002b:00007f4e560eec78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 > RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000458c29 > RDX: 0000000020000080 RSI: 00000000c0481273 RDI: 0000000000000005 > RBP: 000000000073bf00 R08: 0000000000000000 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000246 R12: 00007f4e560ef6d4 > R13: 00000000004c00f2 R14: 00000000004d24f8 R15: 00000000ffffffff > Modules linked in: > ---[ end trace 9ca3bd995bc8baa6 ]--- > RIP: 0010:relay_close_buf+0x28/0x150 kernel/relay.c:495 > Code: 00 00 55 48 89 e5 41 54 49 89 fc 53 e8 a1 1d ff ff 49 8d bc 24 ac 00 > 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <0f> b6 14 02 48 > 89 f8 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85 dc > RSP: 0018:ffff8880976d7918 EFLAGS: 00010202 > RAX: dffffc0000000000 RBX: dffffc0000000000 RCX: ffffc9000e6c3000 > RDX: 0000000020000015 RSI: ffffffff81716f0f RDI: 00000001000000ab > RBP: ffff8880976d7928 R08: ffff88808de7a640 R09: ffffed1012edaefa > R10: ffffed1012edaef9 R11: 0000000000000003 R12: 00000000ffffffff > R13: ffff88809f86a300 R14: 0000000000000007 R15: 00000000ffffffff > FS: 00007f4e560ef700(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 0000000002540040 CR3: 00000000a158b000 CR4: 00000000001406f0 > > > --- > This bug is generated by a bot. It may contain errors. > See https://goo.gl/tpsmEJ for more information about syzbot. > syzbot engineers can be reached at syzkaller@googlegroups.com. > > syzbot will keep track of this bug report. See: > https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
Looking into kernel/relay.c inside relay_open()
....... for_each_online_cpu(i) { buf = relay_open_buf(chan, i); if (!buf) goto free_bufs; *per_cpu_ptr(chan->buf, i) = buf; } ......... relay_open_buf() failed and code goes to *free_bufs*.
.......
free_bufs: for_each_possible_cpu(i) { if ((buf = *per_cpu_ptr(chan->buf, i))) relay_close_buf(buf); } ........
Here buf might assigned with invalid address/ NULL (not sure about its value) and while calling relay_close_buf(), it failed at line 495.
....... static void relay_close_buf(struct rchan_buf *buf) { buf->finalized = 1; //line 495 irq_work_sync(&buf->wakeup_work); buf->chan->cb->remove_buf_file(buf->dentry); kref_put(&buf->kref, relay_remove_buf); }
.......
| |