Re: kern/50664: "cd .." over NFS/ZFS can panic kernel

[Brian Marcotte <marcotte%panix.com@localhost>]

The following reply was made to PR kern/50664; it has been noted by GNATS.

From: Brian Marcotte <marcotte%panix.com@localhost>
To: "J. Hannken-Illjes" <hannken%eis.cs.tu-bs.de@localhost>
Cc: kern-bug-people%netbsd.org@localhost, gnats-admin%netbsd.org@localhost,
	netbsd-bugs%netbsd.org@localhost, gnats-bugs%NetBSD.org@localhost
Subject: Re: kern/50664: "cd .." over NFS/ZFS can panic kernel
Date: Sun, 17 Jan 2016 08:37:51 -0500

 >  Could you add a printf to nfs_cache_enter() to print all nfs nodes
 >  entered into the name cache (not even compile tested here):
 
 Here is some console output with the added printf:
 
 # ls /net/u
 # ls /net/u/.zfs
 enter 0xc1b39dd0 0xc1b39bc0 ".zfs"
 shares    snapshot
 # ./fh
 "/net/." -> 28: 00 8e 00 00 8b 07 00 00 0c 00 00 00 00 63 01 00 c5 6e 7b 02 00 00 00 00 00 00 00 00
 "/net/u/." -> 44: 01 0b 00 00 0b 07 00 00 24 00 00 00 43 86 09 3a 08 5b 05 4e 0a 00 04 00 00 00 00 00 2a 49 55 00 0a 00 04 00 00 00 00 00 2a 49 55 00
 "/net/u/.zfs/." -> 44: 01 0b 00 00 0b 07 00 00 24 00 00 00 43 86 09 3a 08 5b 05 4e 0a 00 01 00 00 00 00 00 00 00 00 00 0a 00 04 00 00 00 00 00 2a 49 55 00
 enter 0xc1b39bc0 0xc1b39a60 "shares"
 "/net/u/.zfs/shares/." -> 44: 01 0b 00 00 0b 07 00 00 24 00 00 00 43 86 09 3a 08 5b 05 4e 0a 00 07 00 00 00 00 00 2a 49 55 00 0a 00 04 00 00 00 00 00 2a 49 55 00
 # ls -l /net/u
 enter 0xc1b39dd0 0xc1b399b0 "1"
 enter 0xc1b39dd0 0xc1b39900 "2"
 enter 0xc1b39dd0 0xc1b39850 "3"
 enter 0xc1b39dd0 0xc1b397a0 "4"
 total 2
 -rw-r--r--  1 root  wheel  0 Jan 17 08:31 1
 -rw-r--r--  1 root  wheel  0 Jan 17 08:31 2
 -rw-r--r--  1 root  wheel  0 Jan 17 08:31 3
 -rw-r--r--  1 root  wheel  0 Jan 17 08:31 4
 # ls /net/u/.zfs/..
 enter 0xc1b39dd0 0xc1b39bc0 ".zfs"
 enter 0xc1b39bc0 0xc1b39dd0 ".."
 1 2 3 4
 # ls /net/u/.zfs/shares/..
 enter 0xc1b39a60 0xc1b39a60 ".."
 panic: kernel diagnostic assertion "dvp != *vpp" failed: file "/misc/devel/netbsd/6.1.5/src/sys/nfs/nfs_vnops.c", line 824
 [...]
 
 --
 - Brian