File xfsprogs-xfs-create-structure-verifier-function-for-short-for.patch of Package xfsprogs.21555

From 31337a6ef7d39381f0407620cbcc0b82ea6ac6be Mon Sep 17 00:00:00 2001
From: "Darrick J. Wong" <darrick.wong@oracle.com>
Date: Mon, 26 Feb 2018 22:43:17 -0600
Subject: [PATCH] xfs: create structure verifier function for short form
 symlinks
Git-commit: 6db3a8007a2493d6887cf45a5edfaa6a770b8492
Patch-mainline: v4.16.0-rc1
References: bsc#1158504

Source kernel commit: 0795e004fd4f2723f3dbf09a195cd7ccf3c74c58

Create a function to check the structure of short form symlink targets.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Eric Sandeen <sandeen@sandeen.net>
Acked-by: Anthony Iliopoulos <ailiopoulos@suse.com>

---
 libxfs/xfs_shared.h         |  1 +
 libxfs/xfs_symlink_remote.c | 34 ++++++++++++++++++++++++++++++++++
 2 files changed, 35 insertions(+)

diff --git a/libxfs/xfs_shared.h b/libxfs/xfs_shared.h
index c6f4eb4..67ccb1a 100644
--- a/libxfs/xfs_shared.h
+++ b/libxfs/xfs_shared.h
@@ -143,5 +143,6 @@ bool xfs_symlink_hdr_ok(xfs_ino_t ino, uint32_t offset,
 			uint32_t size, struct xfs_buf *bp);
 void xfs_symlink_local_to_remote(struct xfs_trans *tp, struct xfs_buf *bp,
 				 struct xfs_inode *ip, struct xfs_ifork *ifp);
+xfs_failaddr_t xfs_symlink_shortform_verify(struct xfs_inode *ip);
 
 #endif /* __XFS_SHARED_H__ */
diff --git a/libxfs/xfs_symlink_remote.c b/libxfs/xfs_symlink_remote.c
index d638530..5a7afd3 100644
--- a/libxfs/xfs_symlink_remote.c
+++ b/libxfs/xfs_symlink_remote.c
@@ -203,3 +203,37 @@ xfs_symlink_local_to_remote(
 	xfs_trans_log_buf(tp, bp, 0, sizeof(struct xfs_dsymlink_hdr) +
 					ifp->if_bytes - 1);
 }
+
+/* Verify the consistency of an inline symlink. */
+xfs_failaddr_t
+xfs_symlink_shortform_verify(
+	struct xfs_inode	*ip)
+{
+	char			*sfp;
+	char			*endp;
+	struct xfs_ifork	*ifp;
+	int			size;
+
+	ASSERT(ip->i_d.di_format == XFS_DINODE_FMT_LOCAL);
+	ifp = XFS_IFORK_PTR(ip, XFS_DATA_FORK);
+	sfp = (char *)ifp->if_u1.if_data;
+	size = ifp->if_bytes;
+	endp = sfp + size;
+
+	/* Zero length symlinks can exist while we're deleting a remote one. */
+	if (size == 0)
+		return NULL;
+
+	/* No negative sizes or overly long symlink targets. */
+	if (size < 0 || size > XFS_SYMLINK_MAXLEN)
+		return __this_address;
+
+	/* No NULLs in the target either. */
+	if (memchr(sfp, 0, size - 1))
+		return __this_address;
+
+	/* We /did/ null-terminate the buffer, right? */
+	if (*endp != 0)
+		return __this_address;
+	return NULL;
+}
-- 
2.16.4