sunrpc: do array overrun check in svc_recv before allocating pages (91c427ac) · Commits · 戴 / test

There's little point in waiting until after we allocate all of the pages to see if we're going to overrun the array. In the event that this calculation is really off we could end up scribbling over a bunch of memory and make it tougher to debug. Signed-off-by:

Jeff Layton <jlayton@redhat.com> Signed-off-by:

J. Bruce Fields <bfields@redhat.com>

net/sunrpc/svc_xprt.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -601,6 +601,7 @@ int svc_recv(struct svc_rqst *rqstp, long timeout)

		/* now allocate needed pages. If we get a failure, sleep briefly */
		pages = (serv->sv_max_mesg + PAGE_SIZE) / PAGE_SIZE;
		BUG_ON(pages >= RPCSVC_MAXPAGES);
		for (i = 0; i < pages ; i++)
		while (rqstp->rq_pages[i] == NULL) {
		struct page *p = alloc_page(GFP_KERNEL);
		@@ -615,7 +616,6 @@ int svc_recv(struct svc_rqst *rqstp, long timeout)
		rqstp->rq_pages[i] = p;
		}
		rqstp->rq_pages[i++] = NULL; /* this might be seen in nfs_read_actor */
		BUG_ON(pages >= RPCSVC_MAXPAGES);

		/* Make arg->head point to first page and arg->pages point to rest */
		arg = &rqstp->rq_arg;

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