From: Theodore Ts'o Date: Mon, 2 Apr 2018 03:21:03 +0000 (-0400) Subject: ext4: force revalidation of directory pointer after seekdir(2) X-Git-Tag: for-linus-20180413~50^2 X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=e40ff213898502d299351cc2fe1e350cd186f0d3;p=linux-block.git ext4: force revalidation of directory pointer after seekdir(2) A malicious user could force the directory pointer to be in an invalid spot by using seekdir(2). Use the mechanism we already have to notice if the directory has changed since the last time we called ext4_readdir() to force a revalidation of the pointer. Reported-by: syzbot+1236ce66f79263e8a862@syzkaller.appspotmail.com Signed-off-by: Theodore Ts'o Cc: stable@vger.kernel.org --- diff --git a/fs/ext4/dir.c b/fs/ext4/dir.c index da87cf757f7d..e2902d394f1b 100644 --- a/fs/ext4/dir.c +++ b/fs/ext4/dir.c @@ -365,13 +365,15 @@ static loff_t ext4_dir_llseek(struct file *file, loff_t offset, int whence) { struct inode *inode = file->f_mapping->host; int dx_dir = is_dx_dir(inode); - loff_t htree_max = ext4_get_htree_eof(file); + loff_t ret, htree_max = ext4_get_htree_eof(file); if (likely(dx_dir)) - return generic_file_llseek_size(file, offset, whence, + ret = generic_file_llseek_size(file, offset, whence, htree_max, htree_max); else - return ext4_llseek(file, offset, whence); + ret = ext4_llseek(file, offset, whence); + file->f_version = inode_peek_iversion(inode) - 1; + return ret; } /*