3.2.89-rc1 review patch. If anyone has any objections, please let me know.
------------------
From: "J. Bruce Fields" <bfields@xxxxxxxxxx>
commit 13bf9fbff0e5e099e2b6f003a0ab8ae145436309 upstream.
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: Tuomas Haanpää <thaan@xxxxxxxxxxxx>
Reported-by: Ari Kauppi <ari@xxxxxxxxxxxx>
Reviewed-by: NeilBrown <neilb@xxxxxxxx>
Signed-off-by: J. Bruce Fields <bfields@xxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
fs/nfsd/nfs3xdr.c | 4 ++++
fs/nfsd/nfsxdr.c | 2 ++
2 files changed, 6 insertions(+)
--- a/fs/nfsd/nfs3xdr.c
+++ b/fs/nfsd/nfs3xdr.c
@@ -363,6 +363,8 @@ nfs3svc_decode_writeargs(struct svc_rqst
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.
*/
@@ -467,6 +469,8 @@ nfs3svc_decode_symlinkargs(struct svc_rq
/* 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++;
--- a/fs/nfsd/nfsxdr.c
+++ b/fs/nfsd/nfsxdr.c
@@ -298,6 +298,8 @@ nfssvc_decode_writeargs(struct svc_rqst
* bytes.
*/
hdr = (void*)p - head->iov_base;
+ if (hdr > head->iov_len)
+ return 0;
dlen = head->iov_len + rqstp->rq_arg.page_len - hdr;
/*