afs: xattr: use scnprintf

sprintf and snprintf are fragile in future maintenance, switch to
using scnprintf to ensure no accidental Use After Free conditions
are introduced.

Signed-off-by: Mark Salyzyn <salyzyn@android.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-fsdevel@vger.kernel.org
Cc: David Howells <dhowells@redhat.com>
Cc: linux-afs@lists.infradead.org
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: David Howells <dhowells@redhat.com>

diff --git a/fs/afs/xattr.c b/fs/afs/xattr.c
index 5552d034090af8ce985d907469261b2cc3d46d18..7af41fd5f3ee4f396aba46849192b1adb3bf51b1 100644 (file)
--- a/fs/afs/xattr.c
+++ b/fs/afs/xattr.c
@@ -228,11 +228,11 @@ static int afs_xattr_get_yfs(const struct xattr_handler *handler,
                break;
        case 1:
                data = buf;
-               dsize = snprintf(buf, sizeof(buf), "%u", yacl->inherit_flag);
+               dsize = scnprintf(buf, sizeof(buf), "%u", yacl->inherit_flag);
                break;
        case 2:
                data = buf;
-               dsize = snprintf(buf, sizeof(buf), "%u", yacl->num_cleaned);
+               dsize = scnprintf(buf, sizeof(buf), "%u", yacl->num_cleaned);
                break;
        case 3:
                data = yacl->vol_acl->data;
@@ -370,13 +370,15 @@ static int afs_xattr_get_fid(const struct xattr_handler *handler,
        /* The volume ID is 64-bit, the vnode ID is 96-bit and the
         * uniquifier is 32-bit.
         */
-       len = sprintf(text, "%llx:", vnode->fid.vid);
+       len = scnprintf(text, sizeof(text), "%llx:", vnode->fid.vid);
        if (vnode->fid.vnode_hi)
-               len += sprintf(text + len, "%x%016llx",
-                              vnode->fid.vnode_hi, vnode->fid.vnode);
+               len += scnprintf(text + len, sizeof(text) - len, "%x%016llx",
+                               vnode->fid.vnode_hi, vnode->fid.vnode);
        else
-               len += sprintf(text + len, "%llx", vnode->fid.vnode);
-       len += sprintf(text + len, ":%x", vnode->fid.unique);
+               len += scnprintf(text + len, sizeof(text) - len, "%llx",
+                                vnode->fid.vnode);
+       len += scnprintf(text + len, sizeof(text) - len, ":%x",
+                        vnode->fid.unique);
 
        if (size == 0)
                return len;