xfs: Check the return value of xfs_buf_read() for NULL

Check the return value of xfs_buf_read() for NULL and return ENOMEM
if it is NULL.  This is necessary in a few spots to avoid subsequent
code blindly dereferencing the null buffer pointer.

Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com>
Signed-off-by: Alex Elder <aelder@sgi.com>

2 files changed, 8 insertions, 0 deletions

diff --git a/fs/xfs/xfs_log_recover.c b/fs/xfs/xfs_log_recover.c
index 1076b7effcdc..b9afff8a1be2 100644
--- a/fs/xfs/xfs_log_recover.c
+++ b/fs/xfs/xfs_log_recover.c
@@ -2131,6 +2131,8 @@ xlog_recover_buffer_pass2(
 
         bp = xfs_buf_read(mp->m_ddev_targp, buf_f->blf_blkno, buf_f->blf_len,
                           buf_flags);
+        if (!bp)
+                return XFS_ERROR(ENOMEM);
         error = xfs_buf_geterror(bp);
         if (error) {
                 xfs_ioerror_alert("xlog_recover_do..(read#1)", mp,
@@ -2222,6 +2224,10 @@ xlog_recover_inode_pass2(
 
         bp = xfs_buf_read(mp->m_ddev_targp, in_f->ilf_blkno, in_f->ilf_len,
                           XBF_LOCK);
+        if (!bp) {
+                error = ENOMEM;
+                goto error;
+        }
         error = xfs_buf_geterror(bp);
         if (error) {
                 xfs_ioerror_alert("xlog_recover_do..(read#2)", mp,
diff --git a/fs/xfs/xfs_vnodeops.c b/fs/xfs/xfs_vnodeops.c
index dd05360ad56f..2a432d00d4c1 100644
--- a/fs/xfs/xfs_vnodeops.c
+++ b/fs/xfs/xfs_vnodeops.c
@@ -83,6 +83,8 @@ xfs_readlink_bmap(
 
                 bp = xfs_buf_read(mp->m_ddev_targp, d, BTOBB(byte_cnt),
                                   XBF_LOCK | XBF_MAPPED | XBF_DONT_BLOCK);
+                if (!bp)
+                        return XFS_ERROR(ENOMEM);
                 error = xfs_buf_geterror(bp);
                 if (error) {
                         xfs_ioerror_alert("xfs_readlink",