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authorMiklos Szeredi <mszeredi@redhat.com>2016-09-01 12:12:00 +0300
committerMiklos Szeredi <mszeredi@redhat.com>2016-09-01 12:12:00 +0300
commit7cb35119d067191ce9ebc380a599db0b03cbd9d9 (patch)
tree15168c61d1f884399b4acdb81eb19092e43b453b /fs/overlayfs/inode.c
parent0eb45fc3bb7a2cf9c9c93d9e95986a841e5f4625 (diff)
downloadlinux-7cb35119d067191ce9ebc380a599db0b03cbd9d9.tar.xz
ovl: listxattr: use strnlen()
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>
Diffstat (limited to 'fs/overlayfs/inode.c')
-rw-r--r--fs/overlayfs/inode.c17
1 files changed, 10 insertions, 7 deletions
diff --git a/fs/overlayfs/inode.c b/fs/overlayfs/inode.c
index 1878591f6a2d..c75625c1efa3 100644
--- a/fs/overlayfs/inode.c
+++ b/fs/overlayfs/inode.c
@@ -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;
}
}