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ovl: copy_up_xattr(): use strnlen 

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>
Cc: <stable@vger.kernel.org>
This commit is contained in:
Miklos Szeredi 2016-09-16 14:12:11 +02:00
parent 9395452b4a
commit 8b326c61de
1 changed files with 11 additions and 1 deletions
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12
fs/overlayfs/copy_up.c
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@ -57,6 +57,7 @@ int ovl_copy_xattr(struct dentry *old, struct dentry *new)
ssize_t list_size, size, value_size = 0; ssize_t list_size, size, value_size = 0;
char *buf, *name, *value = NULL; char *buf, *name, *value = NULL;
int uninitialized_var(error); int uninitialized_var(error);
size_t slen;
if (!old->d_inode->i_op->getxattr || if (!old->d_inode->i_op->getxattr ||
!new->d_inode->i_op->getxattr) !new->d_inode->i_op->getxattr)
@ -79,7 +80,16 @@ int ovl_copy_xattr(struct dentry *old, struct dentry *new)
goto out; 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)) if (ovl_is_private_xattr(name))
continue; continue;
retry: retry: