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Re: [PATCH] Re: Corrupted XFS log replay oops.

To: Dave Chinner <david@xxxxxxxxxxxxx>
Subject: Re: [PATCH] Re: Corrupted XFS log replay oops.
From: Felix Blyakher <felixb@xxxxxxx>
Date: Wed, 21 Jan 2009 23:50:02 -0600
Cc: Nick Piggin <nickpiggin@xxxxxxxxxxxx>, Eric Sesterhenn <snakebyte@xxxxxx>, linux-kernel@xxxxxxxxxxxxxxx, xfs@xxxxxxxxxxx, Pavel Machek <pavel@xxxxxxx>, npiggin@xxxxxxxxxxxx, Chris Mason <chris.mason@xxxxxxxxxx>
In-reply-to: <20090122043747.GU10158@disturbed>
References: <20090113142147.GE16333@alice> <20090120173455.GC21339@alice> <20090121035703.GH10158@disturbed> <200901211503.07308.nickpiggin@xxxxxxxxxxxx> <20090122043747.GU10158@disturbed>

On Jan 21, 2009, at 10:37 PM, Dave Chinner wrote:

On Wed, Jan 21, 2009 at 03:03:06PM +1100, Nick Piggin wrote:
On Wednesday 21 January 2009 14:57:03 Dave Chinner wrote:
[  235.250167] ------------[ cut here ]------------
[  235.250354] kernel BUG at mm/vmalloc.c:164!
[  235.250478] invalid opcode: 0000 [#1] PREEMPT DEBUG_PAGEALLOC
[  235.250869] last sysfs file: /sys/block/ram9/range
[  235.250998] Modules linked in:
......
[  235.251037] Call Trace:
[  235.251037]  [<c01414cf>] ? trace_hardirqs_on+0xb/0xd
[  235.251037]  [<c018367c>] ? vm_map_ram+0x36e/0x38a
[  235.251037]  [<c03b2e1e>] ? _xfs_buf_map_pages+0x42/0x6d
[  235.251037]  [<c03b3773>] ? xfs_buf_get_noaddr+0xbc/0x11f
[  235.251037]  [<c03a2406>] ? xlog_get_bp+0x5a/0x5d
[ 235.251037] [<c03a28fa>] ? xlog_find_verify_log_record +0x26/0x208
[  235.251037]  [<c03a3521>] ? xlog_find_zeroed+0x1d6/0x214
[  235.251037]  [<c03a3584>] ? xlog_find_head+0x25/0x358

.....

Ok, that's crashing in the new vmap code. It might take a couple
of days before I get a chance to look at this, but I've cc'd Nick Piggin
in case he has a chance to look at it before that. It's probably
an XFS bug, anyway.

Hmm, it is crashing in BUG_ON(addr >= end); where this could happen
if XFS asks to map a really huge (or -ve) number of pages and wraps
the range, or if vmap subsystem returns an address right near the
end of the address range and addr+size wraps (which would be a bug
in vmap of course, but I think maybe less likely).

It's a zero length range, not a negative value. A debug XFS would
have assert failed on it, but it was completely unchecked on
production builds. The following patch checks the length of blocks
to build/read/write for being valid. Instead of an oops, we get:

[ 1572.665001] XFS mounting filesystem loop0
[ 1572.666942] XFS: Invalid block length (0x0) given for buffer
[ 1572.667141] XFS: Log inconsistent (didn't find previous header)
[ 1572.667141] XFS: empty log check failed
[ 1572.667141] XFS: log mount/recovery failed: error 5
[ 1572.671487] XFS: log mount failed

Cheers,

Dave.
--
Dave Chinner
david@xxxxxxxxxxxxx

[XFS] Check buffer lengths in log recovery

Before trying to obtain, read or write a buffer,
check that the buffer length is actually valid. If
it is not valid, then something read in the recovery
process has been corrupted and we should abort
recovery.

Reported-by: Eric Sesterhenn <snakebyte@xxxxxx>

Reviewed-by: Felix Blyakher <felixb@xxxxxxx>

---
 fs/xfs/xfs_log_recover.c |   31 +++++++++++++++++++++++++------
 1 files changed, 25 insertions(+), 6 deletions(-)

diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c
index 35cca98..b1047de 100644
--- a/fs/xfs/xfs_log_recover.c
+++ b/fs/xfs/xfs_log_recover.c
@@ -70,16 +70,21 @@ STATIC void xlog_recover_check_summary(xlog_t *);
 xfs_buf_t *
 xlog_get_bp(
        xlog_t          *log,
-       int             num_bblks)
+       int             nbblks)
 {
-       ASSERT(num_bblks > 0);
+       if (nbblks <= 0 || nbblks > log->l_logBBsize) {
+ xlog_warn("XFS: Invalid block length (0x%x) given for buffer", nbblks);
+               XFS_ERROR_REPORT("xlog_get_bp(1)",
+                                XFS_ERRLEVEL_HIGH, log->l_mp);
+               return NULL;
+       }

        if (log->l_sectbb_log) {
-               if (num_bblks > 1)
-                       num_bblks += XLOG_SECTOR_ROUNDUP_BBCOUNT(log, 1);
-               num_bblks = XLOG_SECTOR_ROUNDUP_BBCOUNT(log, num_bblks);
+               if (nbblks > 1)
+                       nbblks += XLOG_SECTOR_ROUNDUP_BBCOUNT(log, 1);
+               nbblks = XLOG_SECTOR_ROUNDUP_BBCOUNT(log, nbblks);
        }
- return xfs_buf_get_noaddr(BBTOB(num_bblks), log->l_mp- >m_logdev_targp);
+       return xfs_buf_get_noaddr(BBTOB(nbblks), log->l_mp->m_logdev_targp);
 }

 void
@@ -102,6 +107,13 @@ xlog_bread(
 {
        int             error;

+       if (nbblks <= 0 || nbblks > log->l_logBBsize) {
+ xlog_warn("XFS: Invalid block length (0x%x) given for buffer", nbblks);
+               XFS_ERROR_REPORT("xlog_bread(1)",
+                                XFS_ERRLEVEL_HIGH, log->l_mp);
+               return EFSCORRUPTED;
+       }
+
        if (log->l_sectbb_log) {
                blk_no = XLOG_SECTOR_ROUNDDOWN_BLKNO(log, blk_no);
                nbblks = XLOG_SECTOR_ROUNDUP_BBCOUNT(log, nbblks);
@@ -139,6 +151,13 @@ xlog_bwrite(
 {
        int             error;

+       if (nbblks <= 0 || nbblks > log->l_logBBsize) {
+ xlog_warn("XFS: Invalid block length (0x%x) given for buffer", nbblks);
+               XFS_ERROR_REPORT("xlog_bwrite(1)",
+                                XFS_ERRLEVEL_HIGH, log->l_mp);
+               return EFSCORRUPTED;
+       }
+
        if (log->l_sectbb_log) {
                blk_no = XLOG_SECTOR_ROUNDDOWN_BLKNO(log, blk_no);
                nbblks = XLOG_SECTOR_ROUNDUP_BBCOUNT(log, nbblks);

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