From a1d47b262952a45aae62bd49cfaf33dd76c11a2c Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Fri, 19 Dec 2014 12:21:47 +0100 Subject: [PATCH] udf: Verify symlink size before loading it 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. CC: stable@vger.kernel.org Reported-by: Carl Henrik Lunde Signed-off-by: Jan Kara --- fs/udf/symlink.c | 17 +++++++++++++---- 1 file changed, 13 insertions(+), 4 deletions(-) diff --git a/fs/udf/symlink.c b/fs/udf/symlink.c index 6fb7945c1e6e..c3aa6fafd6cf 100644 --- a/fs/udf/symlink.c +++ b/fs/udf/symlink.c @@ -80,11 +80,17 @@ static int udf_symlink_filler(struct file *file, struct page *page) 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); @@ -94,8 +100,10 @@ static int udf_symlink_filler(struct file *file, struct page *page) } else { bh = sb_bread(inode->i_sb, pos); - if (!bh) - goto out; + if (!bh) { + err = -EIO; + goto out_unlock_inode; + } symlink = bh->b_data; } @@ -109,9 +117,10 @@ static int udf_symlink_filler(struct file *file, struct page *page) 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;