RE: general protection fault in addr_resolve

[Parav Pandit]

> -----Original Message-----
> From: syzbot <syzbot+20c32fa6ff84a2d28c36@xxxxxxxxxxxxxxxxxxxxxxxxx>
> Sent: Friday, September 21, 2018 3:35 AM
> To: Daniel Jurgens <danielj@xxxxxxxxxxxx>; dledford@xxxxxxxxxx;
> jgg@xxxxxxxx; leon@xxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; linux-
> rdma@xxxxxxxxxxxxxxx; Parav Pandit <parav@xxxxxxxxxxxx>; syzkaller-
> bugs@xxxxxxxxxxxxxxxx
> Subject: general protection fault in addr_resolve
> 
> Hello,
> 
> syzbot found the following crash on:
> 
> HEAD commit:    a0cb0cabe4bb Add linux-next specific files for 20180920
> git tree:       linux-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=14b14e2a400000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=786006c5dafbadf6
> dashboard link:
> https://syzkaller.appspot.com/bug?extid=20c32fa6ff84a2d28c36
> compiler:       gcc (GCC) 8.0.1 20180413 (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+20c32fa6ff84a2d28c36@xxxxxxxxxxxxxxxxxxxxxxxxx
> 
> kasan: GPF could be caused by NULL-ptr deref or user memory access general
> protection fault: 0000 [#1] PREEMPT SMP KASAN
> CPU: 0 PID: 976 Comm: syz-executor4 Not tainted 4.19.0-rc4-next-20180920+
> #76
> Hardware name: Google Google Compute Engine/Google Compute Engine,
> BIOS Google 01/01/2011
> RIP: 0010:copy_src_l2_addr drivers/infiniband/core/addr.c:489 [inline]
> RIP: 0010:rdma_set_src_addr_rcu drivers/infiniband/core/addr.c:518 [inline]
> RIP: 0010:addr_resolve+0x7c4/0x1c90 drivers/infiniband/core/addr.c:593
> Code: 0f 84 dd 01 00 00 e8 9b 6c e9 fb 48 8b 85 d8 fd ff ff 48 8d b8 54 02
> 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 01 38 d0 7c 08 84 d2 0f 85 24
> RSP: 0018:ffff8801c863f360 EFLAGS: 00010202
> RAX: dffffc0000000000 RBX: ffff8801c863f578 RCX: ffffc90003e76000
> RDX: 000000000000003e RSI: ffffffff8593e355 RDI: 00000000000001f1
> RBP: ffff8801c863f5a0 R08: ffff8801d95722c0 R09: ffffed003b585b57
> R10: ffffed003b585b57 R11: ffff8801dac2dabb R12: ffff8801d78a1560
> R13: 0000000000000001 R14: 000000000000000a R15: 0000000000000000
> kobject: 'loop5' (000000009a4a0383): kobject_uevent_env
> FS:  00007fefce9ca700(0000) GS:ffff8801dac00000(0000)
> knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000000000706158 CR3: 00000001d370a000 CR4: 00000000001406f0
> Call Trace:
> kobject: 'loop5' (000000009a4a0383): fill_kobj_path: path =
> '/devices/virtual/block/loop5'
>   rdma_resolve_ip+0x499/0x790 drivers/infiniband/core/addr.c:697
>   rdma_resolve_addr+0x2d6/0x2870 drivers/infiniband/core/cma.c:2992
> kobject: 'loop3' (00000000f158c859): kobject_uevent_env
> kobject: 'loop3' (00000000f158c859): fill_kobj_path: path =
> '/devices/virtual/block/loop3'
>   ucma_resolve_ip+0x242/0x2a0 drivers/infiniband/core/ucma.c:713
>   ucma_write+0x336/0x420 drivers/infiniband/core/ucma.c:1686
>   __vfs_write+0x119/0x9f0 fs/read_write.c:485
> kobject: 'loop2' (00000000ed1b199d): kobject_uevent_env
>   vfs_write+0x1fc/0x560 fs/read_write.c:549
> kobject: 'loop2' (00000000ed1b199d): fill_kobj_path: path =
> '/devices/virtual/block/loop2'
>   ksys_write+0x101/0x260 fs/read_write.c:598
>   __do_sys_write fs/read_write.c:610 [inline]
>   __se_sys_write fs/read_write.c:607 [inline]
>   __x64_sys_write+0x73/0xb0 fs/read_write.c:607
>   do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
>   entry_SYSCALL_64_after_hwframe+0x49/0xbe
> RIP: 0033:0x457679
> Code: 1d b4 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 eb b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00
> RSP: 002b:00007fefce9c9c78 EFLAGS: 00000246 ORIG_RAX:
> 0000000000000001
> RAX: ffffffffffffffda RBX: 00007fefce9ca6d4 RCX: 0000000000457679
> RDX: 0000000000000048 RSI: 0000000020000100 RDI: 0000000000000004
> RBP: 000000000072bf00 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
> R13: 00000000004d8a48 R14: 00000000004cb698 R15: 0000000000000000
> Modules linked in:
> ---[ end trace 416e29924dbdc1a0 ]---
> RIP: 0010:copy_src_l2_addr drivers/infiniband/core/addr.c:489 [inline]
> RIP: 0010:rdma_set_src_addr_rcu drivers/infiniband/core/addr.c:518 [inline]
> RIP: 0010:addr_resolve+0x7c4/0x1c90 drivers/infiniband/core/addr.c:593
> Code: 0f 84 dd 01 00 00 e8 9b 6c e9 fb 48 8b 85 d8 fd ff ff 48 8d b8 54 02
> 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 01 38 d0 7c 08 84 d2 0f 85 24
> kobject: 'loop5' (000000009a4a0383): kobject_uevent_env
> kobject: 'loop5' (000000009a4a0383): fill_kobj_path: path =
> '/devices/virtual/block/loop5'
> RSP: 0018:ffff8801c863f360 EFLAGS: 00010202
> RAX: dffffc0000000000 RBX: ffff8801c863f578 RCX: ffffc90003e76000
> RDX: 000000000000003e RSI: ffffffff8593e355 RDI: 00000000000001f1
> RBP: ffff8801c863f5a0 R08: ffff8801d95722c0 R09: ffffed003b585b57
> R10: ffffed003b585b57 R11: ffff8801dac2dabb R12: ffff8801d78a1560
> R13: 0000000000000001 R14: 000000000000000a R15: 0000000000000000
> FS:  00007fefce9ca700(0000) GS:ffff8801dac00000(0000)
> knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: ffffffffffffffef CR3: 00000001d370a000 CR4: 00000000001406f0
> 
> 
> ---
> This bug is generated by a bot. It may contain errors.
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> syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxxx
> 
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> syzbot.

I think the fix is below.

diff --git a/drivers/infiniband/core/addr.c b/drivers/infiniband/core/addr.c
index 7a0356c..3edd10a 100644
--- a/drivers/infiniband/core/addr.c
+++ b/drivers/infiniband/core/addr.c
@@ -511,7 +511,7 @@ static int rdma_set_src_addr_rcu(struct rdma_dev_addr *dev_addr,
                 * loopback IP address.
                 */
                ndev = rdma_find_ndev_for_src_ip_rcu(dev_net(ndev), dst_in);
-           if (!ndev)
+         if (IS_ERR(dev))
                        return -ENODEV;
        }