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-rw-r--r--fs/nfsd/nfssvc.c36
1 files changed, 36 insertions, 0 deletions
diff --git a/fs/nfsd/nfssvc.c b/fs/nfsd/nfssvc.c
index 31e1f9593457..59979f0bbd4b 100644
--- a/fs/nfsd/nfssvc.c
+++ b/fs/nfsd/nfssvc.c
@@ -747,6 +747,37 @@ static __be32 map_new_errors(u32 vers, __be32 nfserr)
return nfserr;
}
+/*
+ * A write procedure can have a large argument, and a read procedure can
+ * have a large reply, but no NFSv2 or NFSv3 procedure has argument and
+ * reply that can both be larger than a page. The xdr code has taken
+ * advantage of this assumption to be a sloppy about bounds checking in
+ * some cases. Pending a rewrite of the NFSv2/v3 xdr code to fix that
+ * problem, we enforce these assumptions here:
+ */
+static bool nfs_request_too_big(struct svc_rqst *rqstp,
+ struct svc_procedure *proc)
+{
+ /*
+ * The ACL code has more careful bounds-checking and is not
+ * susceptible to this problem:
+ */
+ if (rqstp->rq_prog != NFS_PROGRAM)
+ return false;
+ /*
+ * Ditto NFSv4 (which can in theory have argument and reply both
+ * more than a page):
+ */
+ if (rqstp->rq_vers >= 4)
+ return false;
+ /* The reply will be small, we're OK: */
+ if (proc->pc_xdrressize > 0 &&
+ proc->pc_xdrressize < XDR_QUADLEN(PAGE_SIZE))
+ return false;
+
+ return rqstp->rq_arg.len > PAGE_SIZE;
+}
+
int
nfsd_dispatch(struct svc_rqst *rqstp, __be32 *statp)
{
@@ -759,6 +790,11 @@ nfsd_dispatch(struct svc_rqst *rqstp, __be32 *statp)
rqstp->rq_vers, rqstp->rq_proc);
proc = rqstp->rq_procinfo;
+ if (nfs_request_too_big(rqstp, proc)) {
+ dprintk("nfsd: NFSv%d argument too large\n", rqstp->rq_vers);
+ *statp = rpc_garbage_args;
+ return 1;
+ }
/*
* Give the xdr decoder a chance to change this if it wants
* (necessary in the NFSv4.0 compound case)