[XFS] truncate readdir offsets to signed 32 bit values

John Stanley reported EOVERFLOW errors in readdir from his self-build
glibc.  I traced this down to glibc enabling d_off overflow checks
in one of the about five million different getdents implementations.

In 2.6.28 Dave Woodhouse moved our readdir double buffering required
for NFS4 readdirplus into nfsd and at that point we lost the capping
of the directory offsets to 32 bit signed values.  Johns glibc used
getdents64 to even implement readdir for normal 32 bit offset dirents,
and failed with EOVERFLOW only if this happens on the first dirent in
a getdents call.  I managed to come up with a testcase that uses
raw getdents and does the EOVERFLOW check manually.  We always hit
it with our last entry due to the special end of directory marker.

The patch below is a dumb version of just putting back the masking,
to make sure we have the same behavior as in 2.6.27 and earlier.

I will work on a better and cleaner fix for 2.6.30.

Reported-by: John Stanley <jpsinthemix@verizon.net>
Tested-by: John Stanley <jpsinthemix@verizon.net>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <david@fromorbit.com>
Signed-off-by: Lachlan McIlroy <lachlan@sgi.com>

diff --git a/fs/xfs/xfs_dir2_block.c b/fs/xfs/xfs_dir2_block.c
index e2fa0a1d8e9635b7bff941bb107f4ebb96f05dde..e1f0a06aaf042c945e02f07b872190414122a2b7 100644 (file)
--- a/fs/xfs/xfs_dir2_block.c
+++ b/fs/xfs/xfs_dir2_block.c
@@ -517,9 +517,9 @@ xfs_dir2_block_getdents(
                /*
                 * If it didn't fit, set the final offset to here & return.
                 */
-               if (filldir(dirent, dep->name, dep->namelen, cook,
+               if (filldir(dirent, dep->name, dep->namelen, cook & 0x7fffffff,
                            ino, DT_UNKNOWN)) {
-                       *offset = cook;
+                       *offset = cook & 0x7fffffff;
                        xfs_da_brelse(NULL, bp);
                        return 0;
                }
@@ -529,7 +529,8 @@ xfs_dir2_block_getdents(
         * Reached the end of the block.
         * Set the offset to a non-existent block 1 and return.
         */
-       *offset = xfs_dir2_db_off_to_dataptr(mp, mp->m_dirdatablk + 1, 0);
+       *offset = xfs_dir2_db_off_to_dataptr(mp, mp->m_dirdatablk + 1, 0) &
+                       0x7fffffff;
        xfs_da_brelse(NULL, bp);
        return 0;
 }

diff --git a/fs/xfs/xfs_dir2_leaf.c b/fs/xfs/xfs_dir2_leaf.c
index 93535992cb60e79491b490f07e85a9338dfc0faf..ef805a374eec174c21c77317da7c743ad47b21bf 100644 (file)
--- a/fs/xfs/xfs_dir2_leaf.c
+++ b/fs/xfs/xfs_dir2_leaf.c
@@ -1092,7 +1092,7 @@ xfs_dir2_leaf_getdents(
                 * Won't fit.  Return to caller.
                 */
                if (filldir(dirent, dep->name, dep->namelen,
-                           xfs_dir2_byte_to_dataptr(mp, curoff),
+                           xfs_dir2_byte_to_dataptr(mp, curoff) & 0x7fffffff,
                            ino, DT_UNKNOWN))
                        break;
 
@@ -1108,9 +1108,9 @@ xfs_dir2_leaf_getdents(
         * All done.  Set output offset value to current offset.
         */
        if (curoff > xfs_dir2_dataptr_to_byte(mp, XFS_DIR2_MAX_DATAPTR))
-               *offset = XFS_DIR2_MAX_DATAPTR;
+               *offset = XFS_DIR2_MAX_DATAPTR & 0x7fffffff;
        else
-               *offset = xfs_dir2_byte_to_dataptr(mp, curoff);
+               *offset = xfs_dir2_byte_to_dataptr(mp, curoff) & 0x7fffffff;
        kmem_free(map);
        if (bp)
                xfs_da_brelse(NULL, bp);

diff --git a/fs/xfs/xfs_dir2_sf.c b/fs/xfs/xfs_dir2_sf.c
index b46af0013ec9167d7695273ce037c51029da71bc..a8a8a6efad5b8142dad0689988a35597cbf32554 100644 (file)
--- a/fs/xfs/xfs_dir2_sf.c
+++ b/fs/xfs/xfs_dir2_sf.c
@@ -752,8 +752,8 @@ xfs_dir2_sf_getdents(
 #if XFS_BIG_INUMS
                ino += mp->m_inoadd;
 #endif
-               if (filldir(dirent, ".", 1, dot_offset, ino, DT_DIR)) {
-                       *offset = dot_offset;
+               if (filldir(dirent, ".", 1, dot_offset & 0x7fffffff, ino, DT_DIR)) {
+                       *offset = dot_offset & 0x7fffffff;
                        return 0;
                }
        }
@@ -766,8 +766,8 @@ xfs_dir2_sf_getdents(
 #if XFS_BIG_INUMS
                ino += mp->m_inoadd;
 #endif
-               if (filldir(dirent, "..", 2, dotdot_offset, ino, DT_DIR)) {
-                       *offset = dotdot_offset;
+               if (filldir(dirent, "..", 2, dotdot_offset & 0x7fffffff, ino, DT_DIR)) {
+                       *offset = dotdot_offset & 0x7fffffff;
                        return 0;
                }
        }
@@ -791,14 +791,15 @@ xfs_dir2_sf_getdents(
 #endif
 
                if (filldir(dirent, sfep->name, sfep->namelen,
-                                           off, ino, DT_UNKNOWN)) {
-                       *offset = off;
+                           off & 0x7fffffff, ino, DT_UNKNOWN)) {
+                       *offset = off & 0x7fffffff;
                        return 0;
                }
                sfep = xfs_dir2_sf_nextentry(sfp, sfep);
        }
 
-       *offset = xfs_dir2_db_off_to_dataptr(mp, mp->m_dirdatablk + 1, 0);
+       *offset = xfs_dir2_db_off_to_dataptr(mp, mp->m_dirdatablk + 1, 0) &
+                       0x7fffffff;
        return 0;
 }