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Commit 13bf9fbf authored by J. Bruce Fields's avatar J. Bruce Fields
Browse files

nfsd: stricter decoding of write-like NFSv2/v3 ops 



The NFSv2/v3 code does not systematically check whether we decode past
the end of the buffer.  This generally appears to be harmless, but there
are a few places where we do arithmetic on the pointers involved and
don't account for the possibility that a length could be negative.  Add
checks to catch these.

Reported-by: default avatarTuomas Haanpää <thaan@synopsys.com>
Reported-by: default avatarAri Kauppi <ari@synopsys.com>
Reviewed-by: default avatarNeilBrown <neilb@suse.com>
Cc: stable@vger.kernel.org
Signed-off-by: default avatarJ. Bruce Fields <bfields@redhat.com>
parent db44bac4

fs/nfsd/nfs3xdr.c

+4 −0
Original line number Diff line number Diff line
@@ -369,6 +369,8 @@ nfs3svc_decode_writeargs(struct svc_rqst *rqstp, __be32 *p, 
	args->count = ntohl(*p++);

	args->stable = ntohl(*p++);

	len = args->len = ntohl(*p++);

	if ((void *)p > head->iov_base + head->iov_len)

		return 0;

	/*

	 * The count must equal the amount of data passed.

	 */
@@ -472,6 +474,8 @@ nfs3svc_decode_symlinkargs(struct svc_rqst *rqstp, __be32 *p, 
	/* first copy and check from the first page */

	old = (char*)p;

	vec = &rqstp->rq_arg.head[0];

	if ((void *)old > vec->iov_base + vec->iov_len)

		return 0;

	avail = vec->iov_len - (old - (char*)vec->iov_base);

	while (len && avail && *old) {

		*new++ = *old++;

fs/nfsd/nfsxdr.c

+2 −0
Original line number Diff line number Diff line
@@ -302,6 +302,8 @@ nfssvc_decode_writeargs(struct svc_rqst *rqstp, __be32 *p, 
	 * bytes.

	 */

	hdr = (void*)p - head->iov_base;

	if (hdr > head->iov_len)

		return 0;

	dlen = head->iov_len + rqstp->rq_arg.page_len - hdr;



	/*