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ovl: listxattr: use strnlen()

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commit 7cb35119d0 upstream.

Be defensive about what underlying fs provides us in the returned xattr
list buffer.  If it's not properly null terminated, bail out with a warning
insead of BUG.

Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Miklos Szeredi
2016-09-01 11:12:00 +02:00
committed by Greg Kroah-Hartman
parent d57a6c7480
commit 708cb42fca
1 changed files with 10 additions and 7 deletions
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17
fs/overlayfs/inode.c
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@@ -277,7 +277,8 @@ ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size)
struct path realpath;
enum ovl_path_type type = ovl_path_real(dentry, &realpath);
ssize_t res;
int off;
size_t len;
char *s;
res = vfs_listxattr(realpath.dentry, list, size);
if (res <= 0 || size == 0)
@@ -287,17 +288,19 @@ ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size)
return res;
/* filter out private xattrs */
for (off = 0; off < res;) {
char *s = list + off;
size_t slen = strlen(s) + 1;
for (s = list, len = res; len;) {
size_t slen = strnlen(s, len) + 1;
BUG_ON(off + slen > res);
/* underlying fs providing us with an broken xattr list? */
if (WARN_ON(slen > len))
return -EIO;
len -= slen;
if (ovl_is_private_xattr(s)) {
res -= slen;
memmove(s, s + slen, res - off);
memmove(s, s + slen, len);
} else {
off += slen;
s += slen;
}
}