xfs: More robust inode extent count validation

Source kernel commit: 23fcb3340d033d9f081e21e6c12c2db7eaa541d3

When the inode is in extent format, it can't have more extents that
fit in the inode fork. We don't currenty check this, and so this
corruption goes unnoticed by the inode verifiers. This can lead to
crashes operating on invalid in-memory structures.

Attempts to access such a inode will now error out in the verifier
rather than allowing modification operations to proceed.

Reported-by: Wen Xu <wen.xu@gatech.edu>
Signed-off-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
[darrick: fix a typedef, add some braces and breaks to shut up compiler warnings]
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>

diff --git a/libxfs/xfs_format.h b/libxfs/xfs_format.h
index 146409a3b9e270cc849fc44ac8fbd0e49bf62542..1926905dc6e3fc7226d3705f2e14a49d66923f98 100644 (file)
--- a/libxfs/xfs_format.h
+++ b/libxfs/xfs_format.h
@@ -962,6 +962,9 @@ typedef enum xfs_dinode_fmt {
                XFS_DFORK_DSIZE(dip, mp) : \
                XFS_DFORK_ASIZE(dip, mp))
 
+#define XFS_DFORK_MAXEXT(dip, mp, w) \
+       (XFS_DFORK_SIZE(dip, mp, w) / sizeof(struct xfs_bmbt_rec))
+
 /*
  * Return pointers to the data or attribute forks.
  */

diff --git a/libxfs/xfs_inode_buf.c b/libxfs/xfs_inode_buf.c
index 772ba09e270081bf8d1d1f9c3cf116c0d4294f04..5025f6a1e75d9ae7d0a2c67a30c3774b58cbb3dd 100644 (file)
--- a/libxfs/xfs_inode_buf.c
+++ b/libxfs/xfs_inode_buf.c
@@ -370,6 +370,47 @@ xfs_log_dinode_to_disk(
        }
 }
 
+static xfs_failaddr_t
+xfs_dinode_verify_fork(
+       struct xfs_dinode       *dip,
+       struct xfs_mount        *mp,
+       int                     whichfork)
+{
+       uint32_t                di_nextents = XFS_DFORK_NEXTENTS(dip, whichfork);
+
+       switch (XFS_DFORK_FORMAT(dip, whichfork)) {
+       case XFS_DINODE_FMT_LOCAL:
+               /*
+                * no local regular files yet
+                */
+               if (whichfork == XFS_DATA_FORK) {
+                       if (S_ISREG(be16_to_cpu(dip->di_mode)))
+                               return __this_address;
+                       if (be64_to_cpu(dip->di_size) >
+                                       XFS_DFORK_SIZE(dip, mp, whichfork))
+                               return __this_address;
+               }
+               if (di_nextents)
+                       return __this_address;
+               break;
+       case XFS_DINODE_FMT_EXTENTS:
+               if (di_nextents > XFS_DFORK_MAXEXT(dip, mp, whichfork))
+                       return __this_address;
+               break;
+       case XFS_DINODE_FMT_BTREE:
+               if (whichfork == XFS_ATTR_FORK) {
+                       if (di_nextents > MAXAEXTNUM)
+                               return __this_address;
+               } else if (di_nextents > MAXEXTNUM) {
+                       return __this_address;
+               }
+               break;
+       default:
+               return __this_address;
+       }
+       return NULL;
+}
+
 xfs_failaddr_t
 xfs_dinode_verify(
        struct xfs_mount        *mp,
@@ -437,24 +478,9 @@ xfs_dinode_verify(
        case S_IFREG:
        case S_IFLNK:
        case S_IFDIR:
-               switch (dip->di_format) {
-               case XFS_DINODE_FMT_LOCAL:
-                       /*
-                        * no local regular files yet
-                        */
-                       if (S_ISREG(mode))
-                               return __this_address;
-                       if (di_size > XFS_DFORK_DSIZE(dip, mp))
-                               return __this_address;
-                       if (dip->di_nextents)
-                               return __this_address;
-                       /* fall through */
-               case XFS_DINODE_FMT_EXTENTS:
-               case XFS_DINODE_FMT_BTREE:
-                       break;
-               default:
-                       return __this_address;
-               }
+               fa = xfs_dinode_verify_fork(dip, mp, XFS_DATA_FORK);
+               if (fa)
+                       return fa;
                break;
        case 0:
                /* Uninitialized inode ok. */
@@ -464,17 +490,9 @@ xfs_dinode_verify(
        }
 
        if (XFS_DFORK_Q(dip)) {
-               switch (dip->di_aformat) {
-               case XFS_DINODE_FMT_LOCAL:
-                       if (dip->di_anextents)
-                               return __this_address;
-               /* fall through */
-               case XFS_DINODE_FMT_EXTENTS:
-               case XFS_DINODE_FMT_BTREE:
-                       break;
-               default:
-                       return __this_address;
-               }
+               fa = xfs_dinode_verify_fork(dip, mp, XFS_ATTR_FORK);
+               if (fa)
+                       return fa;
        } else {
                /*
                 * If there is no fork offset, this may be a freshly-made inode