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udf: Verify symlink size before loading it

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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 <chlunde@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
This commit is contained in:
Jan Kara 2014-12-19 12:21:47 +01:00
parent e159332b9a
commit a1d47b2629
1 changed files with 13 additions and 4 deletions
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17
fs/udf/symlink.c
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@ -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;