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SubjectRe: [2.6.21 patch] net/sunrpc/svcsock.c: fix a check
On Mon, 19 Mar 2007 10:33:42 +0100 Adrian Bunk <bunk@stusta.de> wrote:

> The return value of kernel_recvmsg() should be assigned to "err", not
> compared with the random value of a never initialized "err"
> (and the "< 0" check wrongly always returned false since == comparisons
> never have a result < 0).
>
> Spotted by the Coverity checker.
>
> Signed-off-by: Adrian Bunk <bunk@stusta.de>
>
> ---
> --- linux-2.6.21-rc3-mm2/net/sunrpc/svcsock.c.old 2007-03-19 09:44:40.000000000 +0100
> +++ linux-2.6.21-rc3-mm2/net/sunrpc/svcsock.c 2007-03-19 09:45:18.000000000 +0100
> @@ -779,8 +779,8 @@ svc_udp_recvfrom(struct svc_rqst *rqstp)
> }
>
> clear_bit(SK_DATA, &svsk->sk_flags);
> - while ((err == kernel_recvmsg(svsk->sk_sock, &msg, NULL,
> - 0, 0, MSG_PEEK | MSG_DONTWAIT)) < 0 ||
> + while ((err = kernel_recvmsg(svsk->sk_sock, &msg, NULL,
> + 0, 0, MSG_PEEK | MSG_DONTWAIT)) < 0 ||
> (skb = skb_recv_datagram(svsk->sk_sk, 0, 1, &err)) == NULL) {
> if (err == -EAGAIN) {
> svc_sock_received(svsk);

Cute. The compiler must have decided to apply the "(a==b) can never be
less than zero" optimisation before performing uninitialised variable
analysis.

Neil, this one needs runtime testing before we can apply it to 2.6.21, I
think.
-
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