Re: general protection fault in __rds_rdma_map

[Eric Biggers]

On Mon, Nov 27, 2017 at 10:30:01AM -0800, syzbot wrote:
> Hello,
> 
> syzkaller hit the following crash on
> e1d1ea549b57790a3d8cf6300e6ef86118d692a3
> git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/master
> compiler: gcc (GCC) 7.1.1 20170620
> .config is attached
> Raw console output is attached.
> C reproducer is attached
> syzkaller reproducer is attached. See https://goo.gl/kgGztJ
> for information about syzkaller reproducers
> 
> 
> kasan: GPF could be caused by NULL-ptr deref or user memory access
> general protection fault: 0000 [#1] SMP KASAN
> RDS: rds_bind could not find a transport for 224.0.0.2, load rds_tcp or
> rds_rdma?
> Dumping ftrace buffer:
>    (ftrace buffer empty)
> Modules linked in:
> CPU: 1 PID: 3078 Comm: syzkaller719569 Not tainted 4.14.0+ #189
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> Google 01/01/2011
> task: ffff8801cbbda580 task.stack: ffff8801cb8d0000
> RIP: 0010:__rds_rdma_map+0x133/0x1050 net/rds/rdma.c:191
> RSP: 0018:ffff8801cb8d7a28 EFLAGS: 00010206
> RAX: dffffc0000000000 RBX: ffff8801cb8d7bd0 RCX: ffffffff84c0b20d
> RDX: 0000000000000018 RSI: ffff8801cb8d7bd0 RDI: 00000000000000c0
> RBP: ffff8801cb8d7b90 R08: ffffed003971af96 R09: ffffed003971af96
> R10: 0000000000000000 R11: ffffed003971af95 R12: 0000000000000000
> R13: ffff8801cb407480 R14: 0000000000000000 R15: ffff8801cb407480
> FS:  00007fb0be5a3700(0000) GS:ffff8801db500000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007fb0be5a2e78 CR3: 00000001cfc07000 CR4: 00000000001406e0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
>  rds_get_mr_for_dest+0x1bb/0x290 net/rds/rdma.c:357
>  rds_setsockopt+0x6b9/0x970 net/rds/af_rds.c:347
>  SYSC_setsockopt net/socket.c:1851 [inline]
>  SyS_setsockopt+0x189/0x360 net/socket.c:1830
>  entry_SYSCALL_64_fastpath+0x1f/0x96
> RIP: 0033:0x44a789
> RSP: 002b:00007fb0be5a2dc8 EFLAGS: 00000202 ORIG_RAX: 0000000000000036
> RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 000000000044a789
> RDX: 0000000000000007 RSI: 0000400000000114 RDI: 0000000000000004
> RBP: 0000000000000086 R08: 00000000000000a0 R09: 00007fb0be5a3700
> R10: 0000000020000ffc R11: 0000000000000202 R12: 0000000000000000
> R13: 00000000007efe3f R14: 00007fb0be5a39c0 R15: 0000000000000000
> Code: 57 0d 00 00 48 8b 85 f0 fe ff ff 4c 8b a0 c0 04 00 00 48 b8 00 00 00
> 00 00 fc ff df 49 8d bc 24 c0 00 00 00 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f
> 85 6a 0e 00 00 49 83 bc 24 c0 00 00 00 00 0f 84
> RIP: __rds_rdma_map+0x133/0x1050 net/rds/rdma.c:191 RSP: ffff8801cb8d7a28
> ---[ end trace 5e0e31770c7b70a7 ]---
> Kernel panic - not syncing: Fatal exception
> Dumping ftrace buffer:
>    (ftrace buffer empty)
> Kernel Offset: disabled
> Rebooting in 86400 seconds..
> 
> 
> ---
> This bug is generated by a dumb bot. It may contain errors.
> See https://goo.gl/tpsmEJ for details.
> Direct all questions to syzkaller@xxxxxxxxxxxxxxxxx
> Please credit me with: Reported-by: syzbot <syzkaller@xxxxxxxxxxxxxxxx>
> 
> syzbot will keep track of this bug report.
> Once a fix for this bug is committed, please reply to this email with:
> #syz fix: exact-commit-title

Crash is no longer occurring, apparently was fixed by:

#syz fix: rds: Fix NULL pointer dereference in __rds_rdma_map