Avoid reading past buffer when calling GETACL

[karo-tx-linux.git] / fs / nfs / nfs4xdr.c

diff --git a/fs/nfs/nfs4xdr.c b/fs/nfs/nfs4xdr.c
index 77fc5f959c4ecf4322c3846323eb3bf4cdb22081..9312dd78d349e581922a18ef4e9c9ae0671e9da9 100644 (file)
--- a/fs/nfs/nfs4xdr.c
+++ b/fs/nfs/nfs4xdr.c
@@ -4902,11 +4902,19 @@ static int decode_getacl(struct xdr_stream *xdr, struct rpc_rqst *req,
                 bitmap[3] = {0};
        struct kvec *iov = req->rq_rcv_buf.head;
        int status;
+       size_t page_len = xdr->buf->page_len;
 
        res->acl_len = 0;
        if ((status = decode_op_hdr(xdr, OP_GETATTR)) != 0)
                goto out;
+
        bm_p = xdr->p;
+       res->acl_data_offset = be32_to_cpup(bm_p) + 2;
+       res->acl_data_offset <<= 2;
+       /* Check if the acl data starts beyond the allocated buffer */
+       if (res->acl_data_offset > page_len)
+               return -ERANGE;
+
        if ((status = decode_attr_bitmap(xdr, bitmap)) != 0)
                goto out;
        if ((status = decode_attr_length(xdr, &attrlen, &savep)) != 0)
@@ -4916,28 +4924,24 @@ static int decode_getacl(struct xdr_stream *xdr, struct rpc_rqst *req,
                return -EIO;
        if (likely(bitmap[0] & FATTR4_WORD0_ACL)) {
                size_t hdrlen;
-               u32 recvd;
 
                /* The bitmap (xdr len + bitmaps) and the attr xdr len words
                 * are stored with the acl data to handle the problem of
                 * variable length bitmaps.*/
                xdr->p = bm_p;
-               res->acl_data_offset = be32_to_cpup(bm_p) + 2;
-               res->acl_data_offset <<= 2;
 
                /* We ignore &savep and don't do consistency checks on
                 * the attr length.  Let userspace figure it out.... */
                hdrlen = (u8 *)xdr->p - (u8 *)iov->iov_base;
                attrlen += res->acl_data_offset;
-               recvd = req->rq_rcv_buf.len - hdrlen;
-               if (attrlen > recvd) {
+               if (attrlen > page_len) {
                        if (res->acl_flags & NFS4_ACL_LEN_REQUEST) {
                                /* getxattr interface called with a NULL buf */
                                res->acl_len = attrlen;
                                goto out;
                        }
-                       dprintk("NFS: acl reply: attrlen %u > recvd %u\n",
-                                       attrlen, recvd);
+                       dprintk("NFS: acl reply: attrlen %zu > page_len %u\n",
+                                       attrlen, page_len);
                        return -EINVAL;
                }
                xdr_read_pages(xdr, attrlen);