And, another problem spotted by the Synposys folks.
I'll give these some more testing and hope to send a pull request in
another day or two.
--b.
commit a0aa2db91590
Author: J. Bruce Fields <bfields@xxxxxxxxxx>
Date: Fri Apr 21 15:26:30 2017 -0400
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: Tuomas Haanpää <thaan@xxxxxxxxxxxx>
Reported-by: Ari Kauppi <ari@xxxxxxxxxxxx>
Signed-off-by: J. Bruce Fields <bfields@xxxxxxxxxx>
diff --git a/fs/nfsd/nfs3xdr.c b/fs/nfsd/nfs3xdr.c
index dba2ff8eaa68..41cc47bf9d00 100644
--- a/fs/nfsd/nfs3xdr.c
+++ b/fs/nfsd/nfs3xdr.c
@@ -358,6 +358,7 @@ nfs3svc_decode_writeargs(struct svc_rqst *rqstp, __be32 *p,
{
unsigned int len, v, hdr, dlen;
u32 max_blocksize = svc_max_payload(rqstp);
+ struct kvec *head = rqstp->rq_arg.head;
p = decode_fh(p, &args->fh);
if (!p)
@@ -367,6 +368,8 @@ 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.
*/
@@ -466,11 +469,15 @@ nfs3svc_decode_symlinkargs(struct svc_rqst *rqstp, __be32 *p,
len = ntohl(*p++);
if (len == 0 || len > NFS3_MAXPATHLEN || len >= PAGE_SIZE)
return 0;
+ if (!*(rqstp->rq_next_page))
+ return 0;
args->tname = new = page_address(*(rqstp->rq_next_page++));
args->tlen = len;
/* 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++;
diff --git a/fs/nfsd/nfsxdr.c b/fs/nfsd/nfsxdr.c
index 41b468a6a90f..7a0eed7c619d 100644
--- a/fs/nfsd/nfsxdr.c
+++ b/fs/nfsd/nfsxdr.c
@@ -301,6 +301,8 @@ nfssvc_decode_writeargs(struct svc_rqst *rqstp, __be32 *p,
* bytes.
*/
hdr = (void*)p - rqstp->rq_arg.head[0].iov_base;
+ if (hdr > rqstp->rq_arg.head[0].iov_len)
+ return 0;
dlen = rqstp->rq_arg.head[0].iov_len + rqstp->rq_arg.page_len
- hdr;
--
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