Check that we don't run off the end of the inline data buffer when we're
trying to read (apparently corrupt) directory entries. xfs/348
triggered kernel memory being exposed to userspace and a related
complaint from the usercopy code when it corrupts an inline symlink
into an inline dir.
Signed-off-by: Darrick J. Wong <darrick.wong@xxxxxxxxxx>
---
v2: improved comments
---
fs/xfs/xfs_dir2_readdir.c | 17 +++++++++++++++++
1 file changed, 17 insertions(+)
diff --git a/fs/xfs/xfs_dir2_readdir.c b/fs/xfs/xfs_dir2_readdir.c
index 003a99b..26a280b 100644
--- a/fs/xfs/xfs_dir2_readdir.c
+++ b/fs/xfs/xfs_dir2_readdir.c
@@ -69,6 +69,7 @@ xfs_dir2_sf_getdents(
xfs_dir2_dataptr_t dotdot_offset;
xfs_ino_t ino;
struct xfs_da_geometry *geo = args->geo;
+ char *endp;
ASSERT(dp->i_df.if_flags & XFS_IFINLINE);
/*
@@ -83,6 +84,7 @@ xfs_dir2_sf_getdents(
ASSERT(dp->i_df.if_u1.if_data != NULL);
sfp = (xfs_dir2_sf_hdr_t *)dp->i_df.if_u1.if_data;
+ endp = dp->i_df.if_u1.if_data + dp->i_df.if_bytes;
if (dp->i_d.di_size < xfs_dir2_sf_hdr_size(sfp->i8count))
return -EFSCORRUPTED;
@@ -130,6 +132,21 @@ xfs_dir2_sf_getdents(
for (i = 0; i < sfp->count; i++) {
__uint8_t filetype;
+ /*
+ * If we pass the end of the buffer, we're done.
+ *
+ * struct xfs_dir2_sf_entry has a variable length.
+ * Therefore we must first check that the non-variable
+ * parts of the structure don't go off the end of the
+ * buffer, and then we must check that the name
+ * component also does not go off the end of the buffer,
+ * which we do by checking the nextentry pointer.
+ */
+ if (((char *)sfep + sizeof(*sfep)) >= endp ||
+ (char *)dp->d_ops->sf_nextentry(sfp, sfep) > endp) {
+ break;
+ }
+
off = xfs_dir2_db_off_to_dataptr(geo, geo->datablk,
xfs_dir2_sf_get_offset(sfep));
--
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