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ovl: listxattr: use strnlen()

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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>
Cc: <stable@vger.kernel.org>
This commit is contained in:
Miklos Szeredi 2016-09-01 11:12:00 +02:00
parent 0eb45fc3bb
commit 7cb35119d0
1 changed files with 10 additions and 7 deletions
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17
fs/overlayfs/inode.c
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@ -255,7 +255,8 @@ ssize_t ovl_listxattr(struct dentry *dentry, char *list, size_t size)
{
struct dentry *realdentry = ovl_dentry_real(dentry);
ssize_t res;
int off;
size_t len;
char *s;
const struct cred *old_cred;
old_cred = ovl_override_creds(dentry->d_sb);
@ -265,17 +266,19 @@ 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;
}
}