From 630a04e79dd41ff746b545d4fc052e0abb836120 Mon Sep 17 00:00:00 2001
From: "Darrick J. Wong" <darrick.wong@oracle.com>
Date: Wed, 15 Mar 2017 00:24:25 -0700
Subject: xfs: verify inline directory data forks

When we're reading or writing the data fork of an inline directory,
check the contents to make sure we're not overflowing buffers or eating
garbage data.  xfs/348 corrupts an inline symlink into an inline
directory, triggering a buffer overflow bug.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Brian Foster <bfoster@redhat.com>
---
v2: add more checks consistent with _dir2_sf_check and make the verifier
usable from anywhere.
---
 fs/xfs/libxfs/xfs_inode_fork.c | 26 +++++++++++++++++++++++---
 1 file changed, 23 insertions(+), 3 deletions(-)

(limited to 'fs/xfs/libxfs/xfs_inode_fork.c')

diff --git a/fs/xfs/libxfs/xfs_inode_fork.c b/fs/xfs/libxfs/xfs_inode_fork.c
index 25c1e078aef6..9653e964eda4 100644
--- a/fs/xfs/libxfs/xfs_inode_fork.c
+++ b/fs/xfs/libxfs/xfs_inode_fork.c
@@ -33,6 +33,8 @@
 #include "xfs_trace.h"
 #include "xfs_attr_sf.h"
 #include "xfs_da_format.h"
+#include "xfs_da_btree.h"
+#include "xfs_dir2_priv.h"
 
 kmem_zone_t *xfs_ifork_zone;
 
@@ -320,6 +322,7 @@ xfs_iformat_local(
 	int		whichfork,
 	int		size)
 {
+	int		error;
 
 	/*
 	 * If the size is unreasonable, then something
@@ -336,6 +339,14 @@ xfs_iformat_local(
 		return -EFSCORRUPTED;
 	}
 
+	if (S_ISDIR(VFS_I(ip)->i_mode) && whichfork == XFS_DATA_FORK) {
+		error = xfs_dir2_sf_verify(ip->i_mount,
+				(struct xfs_dir2_sf_hdr *)XFS_DFORK_DPTR(dip),
+				size);
+		if (error)
+			return error;
+	}
+
 	xfs_init_local_fork(ip, whichfork, XFS_DFORK_PTR(dip, whichfork), size);
 	return 0;
 }
@@ -856,7 +867,7 @@ xfs_iextents_copy(
  * In these cases, the format always takes precedence, because the
  * format indicates the current state of the fork.
  */
-void
+int
 xfs_iflush_fork(
 	xfs_inode_t		*ip,
 	xfs_dinode_t		*dip,
@@ -866,6 +877,7 @@ xfs_iflush_fork(
 	char			*cp;
 	xfs_ifork_t		*ifp;
 	xfs_mount_t		*mp;
+	int			error;
 	static const short	brootflag[2] =
 		{ XFS_ILOG_DBROOT, XFS_ILOG_ABROOT };
 	static const short	dataflag[2] =
@@ -874,7 +886,7 @@ xfs_iflush_fork(
 		{ XFS_ILOG_DEXT, XFS_ILOG_AEXT };
 
 	if (!iip)
-		return;
+		return 0;
 	ifp = XFS_IFORK_PTR(ip, whichfork);
 	/*
 	 * This can happen if we gave up in iformat in an error path,
@@ -882,12 +894,19 @@ xfs_iflush_fork(
 	 */
 	if (!ifp) {
 		ASSERT(whichfork == XFS_ATTR_FORK);
-		return;
+		return 0;
 	}
 	cp = XFS_DFORK_PTR(dip, whichfork);
 	mp = ip->i_mount;
 	switch (XFS_IFORK_FORMAT(ip, whichfork)) {
 	case XFS_DINODE_FMT_LOCAL:
+		if (S_ISDIR(VFS_I(ip)->i_mode) && whichfork == XFS_DATA_FORK) {
+			error = xfs_dir2_sf_verify(mp,
+					(struct xfs_dir2_sf_hdr *)ifp->if_u1.if_data,
+					ifp->if_bytes);
+			if (error)
+				return error;
+		}
 		if ((iip->ili_fields & dataflag[whichfork]) &&
 		    (ifp->if_bytes > 0)) {
 			ASSERT(ifp->if_u1.if_data != NULL);
@@ -940,6 +959,7 @@ xfs_iflush_fork(
 		ASSERT(0);
 		break;
 	}
+	return 0;
 }
 
 /*
-- 
cgit