udf: Check path length when reading symlink
Symlink reading code does not check whether the resulting path fits into
the page provided by the generic code. This isn't as easy as just
checking the symlink size because of various encoding conversions
we perform on path. So we have to check whether there is still enough
space in the buffer on the fly.
CC: stable@vger.kernel.org
Reported-by: Carl Henrik Lunde <chlunde@ping.uio.no>
Signed-off-by: Jan Kara <jack@suse.cz>
Change-Id: Ife76a9ae43172dcec3c39313642d357e45c3781c
diff --git a/fs/udf/symlink.c b/fs/udf/symlink.c
index d7c6dbe..687ef43 100644
--- a/fs/udf/symlink.c
+++ b/fs/udf/symlink.c
@@ -30,13 +30,16 @@
#include <linux/buffer_head.h>
#include "udf_i.h"
-static void udf_pc_to_char(struct super_block *sb, unsigned char *from,
- int fromlen, unsigned char *to)
+static int udf_pc_to_char(struct super_block *sb, unsigned char *from,
+ int fromlen, unsigned char *to, int tolen)
{
struct pathComponent *pc;
int elen = 0;
+ int comp_len;
unsigned char *p = to;
+ /* Reserve one byte for terminating \0 */
+ tolen--;
while (elen < fromlen) {
pc = (struct pathComponent *)(from + elen);
switch (pc->componentType) {
@@ -49,22 +52,37 @@
break;
/* Fall through */
case 2:
+ if (tolen == 0)
+ return -ENAMETOOLONG;
p = to;
*p++ = '/';
+ tolen--;
break;
case 3:
+ if (tolen < 3)
+ return -ENAMETOOLONG;
memcpy(p, "../", 3);
p += 3;
+ tolen -= 3;
break;
case 4:
+ if (tolen < 2)
+ return -ENAMETOOLONG;
memcpy(p, "./", 2);
p += 2;
+ tolen -= 2;
/* that would be . - just ignore */
break;
case 5:
- p += udf_get_filename(sb, pc->componentIdent, p,
- pc->lengthComponentIdent);
+ comp_len = udf_get_filename(sb, pc->componentIdent,
+ pc->lengthComponentIdent,
+ p, tolen);
+ p += comp_len;
+ tolen -= comp_len;
+ if (tolen == 0)
+ return -ENAMETOOLONG;
*p++ = '/';
+ tolen--;
break;
}
elen += sizeof(struct pathComponent) + pc->lengthComponentIdent;
@@ -73,6 +91,7 @@
p[-1] = '\0';
else
p[0] = '\0';
+ return 0;
}
static int udf_symlink_filler(struct file *file, struct page *page)
@@ -100,8 +119,10 @@
symlink = bh->b_data;
}
- udf_pc_to_char(inode->i_sb, symlink, inode->i_size, p);
+ err = udf_pc_to_char(inode->i_sb, symlink, inode->i_size, p, PAGE_SIZE);
brelse(bh);
+ if (err)
+ goto out_unlock_inode;
up_read(&iinfo->i_data_sem);
SetPageUptodate(page);