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Bug #8168

closed

NULL pointer dereference in zfs_create()

Added by Ezomori Nozomu about 5 years ago. Updated about 5 years ago.

Status:
Closed
Priority:
Low
Category:
zfs - Zettabyte File System
Start date:
2017-05-06
Due date:
% Done:

100%

Estimated time:
0.00 h
Difficulty:
Bite-size
Tags:
needs-triage
Gerrit CR:

Description

If we manage to export the pool on which we are creating a dataset (filesystem or zvol) between entering libzfs`zfs_create() and libzfs`zpool_open() call (for which we never check the return value) we end up dereferencing a NULL pointer in libzfs`zpool_close().

This was discovered on ZFS on Linux. The same issue can be reproduced on Illumos running in parallel:

while :; do zpool import -d /tmp testpool ; zpool export testpool ; done
while :; do zfs create testpool/fs; zfs destroy testpool/fs ; done

Eventually this will result in several core dumps like this one:

[root@52-54-00-d3-7a-01 /cores]# mdb core.zfs.4244
Loading modules: [ libumem.so.1 libc.so.1 libtopo.so.1 libavl.so.1 libnvpair.so.1 ld.so.1 ]
> ::stack
libzfs.so.1`zpool_close+0x17(0, 0, 0, 8047450)
libzfs.so.1`zfs_create+0x1bb(8090548, 8047e6f, 1, 808cba8)
zfs_do_create+0x545(2, 8047d74, 80778a0, 801, 0, 3)
main+0x22c(8047d2c, fef5c6e8, 8047d64, 8055a17, 3, 8047d70)
_start+0x83(3, 8047e64, 8047e68, 8047e6f, 0, 8047e7b)
>

Fix and reproducer (systemtap): https://github.com/zfsonlinux/zfs/pull/6096

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