[PATCH, v2 1/4] ufs: validate maximum fast symlink size from superblock

[Duane Griffin]

The maximum fast symlink size is set in the superblock of certain types
of UFS filesystem. Before using it we need to check that it isn't longer
than the available space we have in the inode.

Signed-off-by: Duane Griffin <duaneg@xxxxxxxxx>
---

Version 1 -> 2:
  * Replaced printk with ufs_warning

 fs/ufs/super.c |   11 +++++++++++
 1 files changed, 11 insertions(+), 0 deletions(-)

diff --git a/fs/ufs/super.c b/fs/ufs/super.c
index e65212d..9613b8c 100644
--- a/fs/ufs/super.c
+++ b/fs/ufs/super.c
@@ -636,6 +636,7 @@ static int ufs_fill_super(struct super_block *sb, void *data, int silent)
 	unsigned block_size, super_block_size;
 	unsigned flags;
 	unsigned super_block_offset;
+	unsigned maxsymlen;
 	int ret = -EINVAL;
 
 	uspi = NULL;
@@ -1069,6 +1070,16 @@ magic_found:
 		uspi->s_maxsymlinklen =
 		    fs32_to_cpu(sb, usb3->fs_un2.fs_44.fs_maxsymlinklen);
 
+	if (uspi->fs_magic == UFS2_MAGIC)
+		maxsymlen = 2 * 4 * (UFS_NDADDR + UFS_NINDIR);
+	else
+		maxsymlen = 4 * (UFS_NDADDR + UFS_NINDIR);
+	if (uspi->s_maxsymlinklen > maxsymlen) {
+		ufs_warning(sb, __func__, "ufs_read_super: excessive maximum "
+			    "fast symlink size (%u)\n", uspi->s_maxsymlinklen);
+		uspi->s_maxsymlinklen = maxsymlen;
+	}
+
 	inode = ufs_iget(sb, UFS_ROOTINO);
 	if (IS_ERR(inode)) {
 		ret = PTR_ERR(inode);
-- 
1.6.0.6

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