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: NEric Sesterhenn <snakebyte@gmx.de>
Tested-by: NEric Sesterhenn <snakebyte@gmx.de>
Reviewed-by: NChristoph Hellwig <hch@infradead.org>
Reviewed-by: NFelix Blyakher <felixb@sgi.com>
Signed-off-by: NDave Chinner <david@fromorbit.com>
Signed-off-by: NFelix Blyakher <felixb@sgi.com>

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);