diff options
| author | Vasily Tarasov <vtaras@openvz.org> | 2006-11-25 11:09:22 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@woody.osdl.org> | 2006-11-25 13:28:33 -0800 |
| commit | 701e054e0c2db82359f0454c7ed4fd24346d52eb (patch) | |
| tree | af052eb937237414705c425f08502517af52e680 | |
| parent | 2d51013ed2f2b6a5d2369b7fbbd989df1f6369e2 (diff) | |
[PATCH] mounstats NULL pointer dereference
OpenVZ developers team has encountered the following problem in 2.6.19-rc6
kernel. After some seconds of running script
while [[ 1 ]]
do
find /proc -name mountstats | xargs cat
done
this Oops appears:
BUG: unable to handle kernel NULL pointer dereference at virtual address
00000010
printing eip:
c01a6b70
*pde = 00000000
Oops: 0000 [#1]
SMP
Modules linked in: xt_length ipt_ttl xt_tcpmss ipt_TCPMSS iptable_mangle
iptable_filter xt_multiport xt_limit ipt_tos ipt_REJECT ip_tables x_tables
parport_pc lp parport sunrpc af_packet thermal processor fan button battery
asus_acpi ac ohci_hcd ehci_hcd usbcore i2c_nforce2 i2c_core tg3 floppy
pata_amd
ide_cd cdrom sata_nv libata
CPU: 1
EIP: 0060:[<c01a6b70>] Not tainted VLI
EFLAGS: 00010246 (2.6.19-rc6 #2)
EIP is at mountstats_open+0x70/0xf0
eax: 00000000 ebx: e6247030 ecx: e62470f8 edx: 00000000
esi: 00000000 edi: c01a6b00 ebp: c33b83c0 esp: f4105eb4
ds: 007b es: 007b ss: 0068
Process cat (pid: 6044, ti=f4105000 task=f4104a70 task.ti=f4105000)
Stack: c33b83c0 c04ee940 f46a4a80 c33b83c0 e4df31b4 c01a6b00 f4105000 c0169231
e4df31b4 c33b83c0 c33b83c0 f4105f20 00000003 f4105000 c0169445 f2503cf0
f7f8c4c0 00008000 c33b83c0 00000000 00008000 c0169350 f4105f20 00008000
Call Trace:
[<c01a6b00>] mountstats_open+0x0/0xf0
[<c0169231>] __dentry_open+0x181/0x250
[<c0169445>] nameidata_to_filp+0x35/0x50
[<c0169350>] do_filp_open+0x50/0x60
[<c01873d6>] seq_read+0xc6/0x300
[<c0169511>] get_unused_fd+0x31/0xc0
[<c01696d3>] do_sys_open+0x63/0x110
[<c01697a7>] sys_open+0x27/0x30
[<c01030bd>] sysenter_past_esp+0x56/0x79
=======================
Code: 45 74 8b 54 24 20 89 44 24 08 8b 42 f0 31 d2 e8 47 cb f8 ff 85 c0 89 c3
74 51 8d 80 a0 04 00 00 e8 46 06 2c 00 8b 83 48 04 00 00 <8b> 78 10 85 ff 74
03
f0 ff 07 b0 01 86 83 a0 04 00 00 f0 ff 4b
EIP: [<c01a6b70>] mountstats_open+0x70/0xf0 SS:ESP 0068:f4105eb4
The problem is that task->nsproxy can be equal NULL for some time during
task exit. This patch fixes the BUG.
Signed-off-by: Vasily Tarasov <vtaras@openvz.org>
Cc: Herbert Poetzl <herbert@13thfloor.at>
Cc: "Serge E. Hallyn" <serue@us.ibm.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
| -rw-r--r-- | fs/proc/base.c | 3 | ||||
| -rw-r--r-- | include/linux/nsproxy.h | 4 |
2 files changed, 5 insertions, 2 deletions
diff --git a/fs/proc/base.c b/fs/proc/base.c index 8df27401d29..795319c54f7 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -442,7 +442,8 @@ static int mountstats_open(struct inode *inode, struct file *file) if (task) { task_lock(task); - namespace = task->nsproxy->namespace; + if (task->nsproxy) + namespace = task->nsproxy->namespace; if (namespace) get_namespace(namespace); task_unlock(task); diff --git a/include/linux/nsproxy.h b/include/linux/nsproxy.h index f6baecdeecd..971d1c6dfc4 100644 --- a/include/linux/nsproxy.h +++ b/include/linux/nsproxy.h @@ -45,8 +45,10 @@ static inline void exit_task_namespaces(struct task_struct *p) { struct nsproxy *ns = p->nsproxy; if (ns) { - put_nsproxy(ns); + task_lock(p); p->nsproxy = NULL; + task_unlock(p); + put_nsproxy(ns); } } #endif |