udf: Verify symlink size before loading it
commit a1d47b262952a45aae62bd49cfaf33dd76c11a2c upstream.
UDF specification allows arbitrarily large symlinks. However we support
only symlinks at most one block large. Check the length of the symlink
so that we don't access memory beyond end of the symlink block.
Reported-by: Carl Henrik Lunde <chlunde@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Zefan Li <lizefan@huawei.com>
diff --git a/fs/udf/symlink.c b/fs/udf/symlink.c
index 687ef43..abfc173 100644
--- a/fs/udf/symlink.c
+++ b/fs/udf/symlink.c
@@ -99,11 +99,17 @@
struct inode *inode = page->mapping->host;
struct buffer_head *bh = NULL;
unsigned char *symlink;
- int err = -EIO;
+ int err;
unsigned char *p = kmap(page);
struct udf_inode_info *iinfo;
uint32_t pos;
+ /* We don't support symlinks longer than one block */
+ if (inode->i_size > inode->i_sb->s_blocksize) {
+ err = -ENAMETOOLONG;
+ goto out_unmap;
+ }
+
iinfo = UDF_I(inode);
pos = udf_block_map(inode, 0);
@@ -113,8 +119,10 @@
} else {
bh = sb_bread(inode->i_sb, pos);
- if (!bh)
- goto out;
+ if (!bh) {
+ err = -EIO;
+ goto out_unlock_inode;
+ }
symlink = bh->b_data;
}
@@ -130,9 +138,10 @@
unlock_page(page);
return 0;
-out:
+out_unlock_inode:
up_read(&iinfo->i_data_sem);
SetPageError(page);
+out_unmap:
kunmap(page);
unlock_page(page);
return err;