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authorJ. Bruce Fields <bfields@redhat.com>2017-04-21 15:26:30 -0400
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-05-08 07:46:02 +0200
commitda1ce38aaac7f08d319b4b76130aa4fd27c4489f (patch)
tree26946370f834a2cc6f05c764f5c8e974354298e4
parent35e13333c217f0255a1e657ce075f0f72bc6383c (diff)
nfsd: stricter decoding of write-like NFSv2/v3 ops
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@synopsys.com> Reported-by: Ari Kauppi <ari@synopsys.com> Reviewed-by: NeilBrown <neilb@suse.com> Signed-off-by: J. Bruce Fields <bfields@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--fs/nfsd/nfs3xdr.c4
-rw-r--r--fs/nfsd/nfsxdr.c2
2 files changed, 6 insertions, 0 deletions
diff --git a/fs/nfsd/nfs3xdr.c b/fs/nfsd/nfs3xdr.c
index 34f4d1b74a23..7162ab7bc093 100644
--- a/fs/nfsd/nfs3xdr.c
+++ b/fs/nfsd/nfs3xdr.c
@@ -368,6 +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.
*/
@@ -471,6 +473,8 @@ 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++;
diff --git a/fs/nfsd/nfsxdr.c b/fs/nfsd/nfsxdr.c
index 894f2a8ffe7a..bf913201a6ad 100644
--- a/fs/nfsd/nfsxdr.c
+++ b/fs/nfsd/nfsxdr.c
@@ -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;
/*