[patch 17/20] dm: BUG/OOPS fix

Greg KH
2006-08-21T18:50:09Z

[-- Attachment #1: dm-bug-oops-fix.patch --]
[-- Type: text/plain, Size: 2568 bytes --]

-stable review patch. If anyone has any objections, please let us know.

------------------
From: Michal Miroslaw <mirq-linux@rere.qmqm.pl>

Fix BUG I tripped on while testing failover and multipathing.

BUG shows up on error path in multipath_ctr() when parse_priority_group()
fails after returning at least once without error. The fix is to
initialize m->ti early - just after alloc()ing it.

BUG: unable to handle kernel NULL pointer dereference at virtual address 00000000
printing eip:
c027c3d2
*pde = 00000000
Oops: 0000 [#3]
Modules linked in: qla2xxx ext3 jbd mbcache sg ide_cd cdrom floppy
CPU: 0
EIP: 0060:[<c027c3d2>] Not tainted VLI
EFLAGS: 00010202 (2.6.17.3 #1)
EIP is at dm_put_device+0xf/0x3b
eax: 00000001 ebx: ee4fcac0 ecx: 00000000 edx: ee4fcac0
esi: ee4fc4e0 edi: ee4fc4e0 ebp: 00000000 esp: c5db3e78
ds: 007b es: 007b ss: 0068
Process multipathd (pid: 15912, threadinfo=c5db2000 task=ef485a90)
Stack: ec4eda40 c02816bd ee4fc4c0 00000000 f7e89498 f883e0bc c02816f6 f7e89480
f7e8948c c0281801 ffffffea f7e89480 f883e080 c0281ffe 00000001 00000000
00000004 dfe9cab8 f7a693c0 f883e080 f883e0c0 ca4b99c0 c027c6ee 01400000
Call Trace:
<c02816bd> free_pgpaths+0x31/0x45 <c02816f6> free_priority_group+0x25/0x2e
<c0281801> free_multipath+0x35/0x67 <c0281ffe> multipath_ctr+0x123/0x12d
<c027c6ee> dm_table_add_target+0x11e/0x18b <c027e5b4> populate_table+0x8a/0xaf
<c027e62b> table_load+0x52/0xf9 <c027ec23> ctl_ioctl+0xca/0xfc
<c027e5d9> table_load+0x0/0xf9 <c0152146> do_ioctl+0x3e/0x43
<c0152360> vfs_ioctl+0x16c/0x178 <c01523b4> sys_ioctl+0x48/0x60
<c01029b3> syscall_call+0x7/0xb
Code: 97 f0 00 00 00 89 c1 83 c9 01 80 e2 01 0f 44 c1 88 43 14 8b 04 24 59 5b 5e 5f 5d c3 53 89 c1 89 d3 ff 4a 08 0f 94 c0 84 c0 74 2a <8b> 01 8b 10 89 d8 e8 f6 fb ff ff 8b 03 8b 53 04 89 50 04 89 02
EIP: [<c027c3d2>] dm_put_device+0xf/0x3b SS:ESP 0068:c5db3e78

Signed-off-by: Michal Miroslaw <mirq-linux@rere.qmqm.pl>
Acked-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
drivers/md/dm-mpath.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

--- linux-2.6.17.9.orig/drivers/md/dm-mpath.c
+++ linux-2.6.17.9/drivers/md/dm-mpath.c
@@ -711,6 +711,8 @@ static int multipath_ctr(struct dm_targe
return -EINVAL;
}

+ m->ti = ti;
+
r = parse_features(&as, m, ti);
if (r)
goto bad;
@@ -752,7 +754,6 @@ static int multipath_ctr(struct dm_targe
}

ti->private = m;
- m->ti = ti;

return 0;

--