From 57fe93b374a6b8711995c2d466c502af9f3a08bb Mon Sep 17 00:00:00 2001 From: "David S. Miller" Date: Wed, 10 Nov 2010 10:38:24 -0800 Subject: [PATCH] filter: make sure filters dont read uninitialized memory There is a possibility malicious users can get limited information about uninitialized stack mem array. Even if sk_run_filter() result is bound to packet length (0 .. 65535), we could imagine this can be used by hostile user. Initializing mem[] array, like Dan Rosenberg suggested in his patch is expensive since most filters dont even use this array. Its hard to make the filter validation in sk_chk_filter(), because of the jumps. This might be done later. In this patch, I use a bitmap (a single long var) so that only filters using mem[] loads/stores pay the price of added security checks. For other filters, additional cost is a single instruction. [ Since we access fentry->k a lot now, cache it in a local variable and mark filter entry pointer as const. -DaveM ] Reported-by: Dan Rosenberg Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller --- Reading git-format-patch failed