Fix CVE-2017-7645 (rhbz 1443615 1443617)

1 files changed, 180 insertions, 0 deletions

diff --git a/CVE-2017-7645.patch b/CVE-2017-7645.patch
new file mode 100644
index 000000000..0be019cc3
--- /dev/null
+++ b/CVE-2017-7645.patch
@@ -0,0 +1,180 @@
+From: "J. Bruce Fields" <bfields@redhat.com>
+Date:       2017-04-14 15:04:40
+Subject:    [PATCH] nfsd: check for oversized NFSv2/v3 arguments
+
+A client can append random data to the end of an NFSv2 or NFSv3 RPC call
+without our complaining; we'll just stop parsing at the end of the
+expected data and ignore the rest.
+
+Encoded arguments and replies are stored together in an array of pages,
+and if a call is too large it could leave inadequate space for the
+reply.  This is normally OK because NFS RPC's typically have either
+short arguments and long replies (like READ) or long arguments and short
+replies (like WRITE).  But a client that sends an incorrectly long reply
+can violate those assumptions.  This was observed to cause crashes.
+
+So, insist that the argument not be any longer than we expect.
+
+Also, several operations increment rq_next_page in the decode routine
+before checking the argument size, which can leave rq_next_page pointing
+well past the end of the page array, causing trouble later in
+svc_free_pages.
+
+As followup we may also want to rewrite the encoding routines to check
+more carefully that they aren't running off the end of the page array.
+
+Reported-by: Tuomas Haanpää <thaan@synopsys.com>
+Reported-by: Ari Kauppi <ari@synopsys.com>
+Cc: stable@vger.kernel.org
+Signed-off-by: J. Bruce Fields <bfields@redhat.com>
+---
+ fs/nfsd/nfs3xdr.c          | 23 +++++++++++++++++------
+ fs/nfsd/nfsxdr.c           | 13 ++++++++++---
+ include/linux/sunrpc/svc.h |  3 +--
+ 3 files changed, 28 insertions(+), 11 deletions(-)
+
+diff --git a/fs/nfsd/nfs3xdr.c b/fs/nfsd/nfs3xdr.c
+index dba2ff8eaa68..be66bcadfaea 100644
+--- a/fs/nfsd/nfs3xdr.c
++++ b/fs/nfsd/nfs3xdr.c
+@@ -334,8 +334,11 @@ nfs3svc_decode_readargs(struct svc_rqst *rqstp, __be32 *p,
+ 	if (!p)
+ 		return 0;
+ 	p = xdr_decode_hyper(p, &args->offset);
+-
+ 	args->count = ntohl(*p++);
++
++	if (!xdr_argsize_check(rqstp, p))
++		return 0;
++
+ 	len = min(args->count, max_blocksize);
+ 
+ 	/* set up the kvec */
+@@ -349,7 +352,7 @@ nfs3svc_decode_readargs(struct svc_rqst *rqstp, __be32 *p,
+ 		v++;
+ 	}
+ 	args->vlen = v;
+-	return xdr_argsize_check(rqstp, p);
++	return 1;
+ }
+ 
+ int
+@@ -536,9 +539,11 @@ nfs3svc_decode_readlinkargs(struct svc_rqst *rqstp, __be32 *p,
+ 	p = decode_fh(p, &args->fh);
+ 	if (!p)
+ 		return 0;
++	if (!xdr_argsize_check(rqstp, p))
++		return 0;
+ 	args->buffer = page_address(*(rqstp->rq_next_page++));
+ 
+-	return xdr_argsize_check(rqstp, p);
++	return 1;
+ }
+ 
+ int
+@@ -564,10 +569,14 @@ nfs3svc_decode_readdirargs(struct svc_rqst *rqstp, __be32 *p,
+ 	args->verf   = p; p += 2;
+ 	args->dircount = ~0;
+ 	args->count  = ntohl(*p++);
++
++	if (!xdr_argsize_check(rqstp, p))
++		return 0;
++
+ 	args->count  = min_t(u32, args->count, PAGE_SIZE);
+ 	args->buffer = page_address(*(rqstp->rq_next_page++));
+ 
+-	return xdr_argsize_check(rqstp, p);
++	return 1;
+ }
+ 
+ int
+@@ -585,6 +594,9 @@ nfs3svc_decode_readdirplusargs(struct svc_rqst *rqstp, __be32 *p,
+ 	args->dircount = ntohl(*p++);
+ 	args->count    = ntohl(*p++);
+ 
++	if (!xdr_argsize_check(rqstp, p))
++		return 0;
++
+ 	len = args->count = min(args->count, max_blocksize);
+ 	while (len > 0) {
+ 		struct page *p = *(rqstp->rq_next_page++);
+@@ -592,8 +604,7 @@ nfs3svc_decode_readdirplusargs(struct svc_rqst *rqstp, __be32 *p,
+ 			args->buffer = page_address(p);
+ 		len -= PAGE_SIZE;
+ 	}
+-
+-	return xdr_argsize_check(rqstp, p);
++	return 1;
+ }
+ 
+ int
+diff --git a/fs/nfsd/nfsxdr.c b/fs/nfsd/nfsxdr.c
+index 41b468a6a90f..79268369f7b3 100644
+--- a/fs/nfsd/nfsxdr.c
++++ b/fs/nfsd/nfsxdr.c
+@@ -257,6 +257,9 @@ nfssvc_decode_readargs(struct svc_rqst *rqstp, __be32 *p,
+ 	len = args->count     = ntohl(*p++);
+ 	p++; /* totalcount - unused */
+ 
++	if (!xdr_argsize_check(rqstp, p))
++		return 0;
++
+ 	len = min_t(unsigned int, len, NFSSVC_MAXBLKSIZE_V2);
+ 
+ 	/* set up somewhere to store response.
+@@ -272,7 +275,7 @@ nfssvc_decode_readargs(struct svc_rqst *rqstp, __be32 *p,
+ 		v++;
+ 	}
+ 	args->vlen = v;
+-	return xdr_argsize_check(rqstp, p);
++	return 1;
+ }
+ 
+ int
+@@ -360,9 +363,11 @@ nfssvc_decode_readlinkargs(struct svc_rqst *rqstp, __be32 *p, struct nfsd_readli
+ 	p = decode_fh(p, &args->fh);
+ 	if (!p)
+ 		return 0;
++	if (!xdr_argsize_check(rqstp, p))
++		return 0;
+ 	args->buffer = page_address(*(rqstp->rq_next_page++));
+ 
+-	return xdr_argsize_check(rqstp, p);
++	return 1;
+ }
+ 
+ int
+@@ -400,9 +405,11 @@ nfssvc_decode_readdirargs(struct svc_rqst *rqstp, __be32 *p,
+ 	args->cookie = ntohl(*p++);
+ 	args->count  = ntohl(*p++);
+ 	args->count  = min_t(u32, args->count, PAGE_SIZE);
++	if (!xdr_argsize_check(rqstp, p))
++		return 0;
+ 	args->buffer = page_address(*(rqstp->rq_next_page++));
+ 
+-	return xdr_argsize_check(rqstp, p);
++	return 1;
+ }
+ 
+ /*
+diff --git a/include/linux/sunrpc/svc.h b/include/linux/sunrpc/svc.h
+index e770abeed32d..6ef19cf658b4 100644
+--- a/include/linux/sunrpc/svc.h
++++ b/include/linux/sunrpc/svc.h
+@@ -336,8 +336,7 @@ xdr_argsize_check(struct svc_rqst *rqstp, __be32 *p)
+ {
+ 	char *cp = (char *)p;
+ 	struct kvec *vec = &rqstp->rq_arg.head[0];
+-	return cp >= (char*)vec->iov_base
+-		&& cp <= (char*)vec->iov_base + vec->iov_len;
++	return cp == (char *)vec->iov_base + vec->iov_len;
+ }
+ 
+ static inline int
+-- 
+2.9.3
+
+--
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