[PATCH 3.15 038/109] net: filter: fix upper BPF instruction limit

Greg Kroah-Hartman
2014-07-26T19:18:25Z

From: Kees Cook <keescook@chromium.org>

[ Upstream commit 6f9a093b66ce7cacc110d8737c03686e80ecfda6 ]

The original checks (via sk_chk_filter) for instruction count uses ">",
not ">=", so changing this in sk_convert_filter has the potential to break
existing seccomp filters that used exactly BPF_MAXINSNS many instructions.

Fixes: bd4cf0ed331a ("net: filter: rework/optimize internal BPF interpreter's instruction set")
Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: stable@vger.kernel.org # v3.15+
Acked-by: Daniel Borkmann <dborkman@redhat.com>
Acked-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/core/filter.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -872,7 +872,7 @@ int sk_convert_filter(struct sock_filter
BUILD_BUG_ON(BPF_MEMWORDS * sizeof(u32) > MAX_BPF_STACK);
BUILD_BUG_ON(FP_REG + 1 != MAX_BPF_REG);

- if (len <= 0 || len >= BPF_MAXINSNS)
+ if (len <= 0 || len > BPF_MAXINSNS)
return -EINVAL;

if (new_prog) {