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ovl: copy_up_xattr(): use strnlen

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commit 8b326c61de08f5ca4bc454a168f19e7e43c4cc2a upstream.

Be defensive about what underlying fs provides us in the returned xattr
list buffer.  strlen() may overrun the buffer, so use strnlen() and WARN if
the contents are not properly null terminated.

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Miklos Szeredi 2016-09-16 14:12:11 +02:00 committed by Greg Kroah-Hartman
parent 0a5600d83f
commit 714ac6de44
1 changed files with 11 additions and 1 deletions
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12
fs/overlayfs/copy_up.c
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@ -25,6 +25,7 @@ int ovl_copy_xattr(struct dentry *old, struct dentry *new)
ssize_t list_size, size, value_size = 0;
char *buf, *name, *value = NULL;
int uninitialized_var(error);
size_t slen;
if (!old->d_inode->i_op->getxattr ||
!new->d_inode->i_op->getxattr)
@ -47,7 +48,16 @@ int ovl_copy_xattr(struct dentry *old, struct dentry *new)
goto out;
}
for (name = buf; name < (buf + list_size); name += strlen(name) + 1) {
for (name = buf; list_size; name += slen) {
slen = strnlen(name, list_size) + 1;
/* underlying fs providing us with an broken xattr list? */
if (WARN_ON(slen > list_size)) {
error = -EIO;
break;
}
list_size -= slen;
if (ovl_is_private_xattr(name))
continue;
retry: