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Date: Sun, 13 Jul 2014 19:07:32 +0200 From: Alexei Starovoitov <alexei.starovoitov@...il.com> To: Christoph Schulz <develop@...stov.de> Cc: "netdev@...r.kernel.org" <netdev@...r.kernel.org>, linux-ppp@...r.kernel.org, paulus@...ba.org, isdn@...ux-pingi.de Subject: Re: [PATCH net 1/1] net: ppp: don't call sk_chk_filter twice On Sun, Jul 13, 2014 at 3:01 PM, Christoph Schulz <develop@...stov.de> wrote: > From: Christoph Schulz <develop@...stov.de> > > Commit 568f194e8bd16c353ad50f9ab95d98b20578a39d ("net: ppp: use > sk_unattached_filter api") causes sk_chk_filter() to be called twice when > setting a PPP pass or active filter. This applies to both the generic PPP > subsystem implemented by drivers/net/ppp/ppp_generic.c and the ISDN PPP > subsystem implemented by drivers/isdn/i4l/isdn_ppp.c. The first call is from > within get_filter(). The second one is through the call chain > > ppp_ioctl() or isdn_ppp_ioctl() > --> sk_unattached_filter_create() > --> __sk_prepare_filter() > --> sk_chk_filter() > > The first call from within get_filter() should be deleted as get_filter() is > called just before calling sk_unattached_filter_create() later on, which > eventually calls sk_chk_filter() anyway. > > For 3.15.x, this proposed change is a bugfix rather than a pure optimization as > in that branch, sk_chk_filter() may replace filter codes by other codes which > are not recognized when executing sk_chk_filter() a second time. So with > 3.15.x, if sk_chk_filter() is called twice, the second invocation may yield > EINVAL (this depends on the filter codes found in the filter to be set, but > because the replacement is done for frequently used codes, this is almost > always the case). The net effect is that setting pass and/or active PPP filters > does not work anymore, since sk_unattached_filter_create() always returns > EINVAL due to the second call to sk_chk_filter(), regardless whether the filter > was originally sane or not. > > Signed-off-by: Christoph Schulz <develop@...stov.de> Acked-by: Alexei Starovoitov <ast@...mgrid.com> Thank you for fixing it. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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