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udf: Verify symlink size before loading it 

commit a1d47b2629 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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Jan Kara 2014-12-19 12:21:47 +01:00 committed by Greg Kroah-Hartman
parent 1a1f1f00e6
commit 5c90d03628
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;