NFS: Let xdr_read_pages() check for buffer overflows

xdr_read_pages will already do all of the buffer overflow checks that are
currently being open-coded in the various callers. This patch simplifies
the existing code by replacing the open coded checks.

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 3 insertions, 20 deletions

diff --git a/fs/nfs/nfs3xdr.c b/fs/nfs/nfs3xdr.c
index 3c61c7f80a4b..d64a00ff5a16 100644
--- a/fs/nfs/nfs3xdr.c
+++ b/fs/nfs/nfs3xdr.c
@@ -246,7 +246,6 @@ static void encode_nfspath3(struct xdr_stream *xdr, struct page **pages,
 static int decode_nfspath3(struct xdr_stream *xdr)
 {
         u32 recvd, count;
-        size_t hdrlen;
         __be32 *p;
 
         p = xdr_inline_decode(xdr, 4);
@@ -255,12 +254,9 @@ static int decode_nfspath3(struct xdr_stream *xdr)
         count = be32_to_cpup(p);
         if (unlikely(count >= xdr->buf->page_len || count > NFS3_MAXPATHLEN))
                 goto out_nametoolong;
-        hdrlen = (u8 *)xdr->p - (u8 *)xdr->iov->iov_base;
-        recvd = xdr->buf->len - hdrlen;
+        recvd = xdr_read_pages(xdr, count);
         if (unlikely(count > recvd))
                 goto out_cheating;
-
-        xdr_read_pages(xdr, count);
         xdr_terminate_string(xdr->buf, count);
         return 0;
 
@@ -1587,7 +1583,6 @@ static int decode_read3resok(struct xdr_stream *xdr,
                              struct nfs_readres *result)
 {
         u32 eof, count, ocount, recvd;
-        size_t hdrlen;
         __be32 *p;
 
         p = xdr_inline_decode(xdr, 4 + 4 + 4);
@@ -1598,13 +1593,10 @@ static int decode_read3resok(struct xdr_stream *xdr,
         ocount = be32_to_cpup(p++);
         if (unlikely(ocount != count))
                 goto out_mismatch;
-        hdrlen = (u8 *)xdr->p - (u8 *)xdr->iov->iov_base;
-        recvd = xdr->buf->len - hdrlen;
+        recvd = xdr_read_pages(xdr, count);
         if (unlikely(count > recvd))
                 goto out_cheating;
-
 out:
-        xdr_read_pages(xdr, count);
         result->eof = eof;
         result->count = count;
         return count;
@@ -2039,16 +2031,7 @@ out_truncated:
  */
 static int decode_dirlist3(struct xdr_stream *xdr)
 {
-        u32 recvd, pglen;
-        size_t hdrlen;
-
-        pglen = xdr->buf->page_len;
-        hdrlen = (u8 *)xdr->p - (u8 *)xdr->iov->iov_base;
-        recvd = xdr->buf->len - hdrlen;
-        if (pglen > recvd)
-                pglen = recvd;
-        xdr_read_pages(xdr, pglen);
-        return pglen;
+        return xdr_read_pages(xdr, xdr->buf->page_len);
 }
 
 static int decode_readdir3resok(struct xdr_stream *xdr,