From 3a9af0bd34410a255d27024ea1bc28dc4e3a0044 Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Tue, 17 Feb 2015 13:47:58 -0800 Subject: [PATCH] samples/seccomp: improve label helper Fixes a potential corruption with uninitialized stack memory in the seccomp BPF sample program. [akpm@linux-foundation.org: coding-style fixlet] Signed-off-by: Kees Cook Reported-by: Robert Swiecki Tested-by: Robert Swiecki Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- samples/seccomp/bpf-fancy.c | 4 +++- samples/seccomp/bpf-helper.c | 6 ++++++ 2 files changed, 9 insertions(+), 1 deletion(-) diff --git a/samples/seccomp/bpf-fancy.c b/samples/seccomp/bpf-fancy.c index 8eb483aaec46..e8b24f443709 100644 --- a/samples/seccomp/bpf-fancy.c +++ b/samples/seccomp/bpf-fancy.c @@ -25,7 +25,9 @@ int main(int argc, char **argv) { - struct bpf_labels l; + struct bpf_labels l = { + .count = 0, + }; static const char msg1[] = "Please type something: "; static const char msg2[] = "You typed: "; char buf[256]; diff --git a/samples/seccomp/bpf-helper.c b/samples/seccomp/bpf-helper.c index 579cfe331886..05cb4d5ff9f5 100644 --- a/samples/seccomp/bpf-helper.c +++ b/samples/seccomp/bpf-helper.c @@ -10,6 +10,7 @@ */ #include +#include #include #include "bpf-helper.h" @@ -63,6 +64,11 @@ __u32 seccomp_bpf_label(struct bpf_labels *labels, const char *label) { struct __bpf_label *begin = labels->labels, *end; int id; + + if (labels->count == BPF_LABELS_MAX) { + fprintf(stderr, "Too many labels\n"); + exit(1); + } if (labels->count == 0) { begin->label = label; begin->location = 0xffffffff;