From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:60225 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753419AbbIZSQC (ORCPT ); Sat, 26 Sep 2015 14:16:02 -0400 Subject: Patch "x86: bpf_jit: fix compilation of large bpf programs" has been added to the 3.10-stable tree To: ast@plumgrid.com, daniel@iogearbox.net, davem@davemloft.net, gregkh@linuxfoundation.org, jslaby@suse.cz Cc: , From: Date: Sat, 26 Sep 2015 11:16:01 -0700 Message-ID: <1443291361140101@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: This is a note to let you know that I've just added the patch titled x86: bpf_jit: fix compilation of large bpf programs to the 3.10-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: x86-bpf_jit-fix-compilation-of-large-bpf-programs.patch and it can be found in the queue-3.10 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. >>From 3f7352bf21f8fd7ba3e2fcef9488756f188e12be Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Fri, 22 May 2015 15:42:55 -0700 Subject: x86: bpf_jit: fix compilation of large bpf programs From: Alexei Starovoitov commit 3f7352bf21f8fd7ba3e2fcef9488756f188e12be upstream. x86 has variable length encoding. x86 JIT compiler is trying to pick the shortest encoding for given bpf instruction. While doing so the jump targets are changing, so JIT is doing multiple passes over the program. Typical program needs 3 passes. Some very short programs converge with 2 passes. Large programs may need 4 or 5. But specially crafted bpf programs may hit the pass limit and if the program converges on the last iteration the JIT compiler will be producing an image full of 'int 3' insns. Fix this corner case by doing final iteration over bpf program. Fixes: 0a14842f5a3c ("net: filter: Just In Time compiler for x86-64") Reported-by: Daniel Borkmann Signed-off-by: Alexei Starovoitov Tested-by: Daniel Borkmann Acked-by: Daniel Borkmann Signed-off-by: David S. Miller Signed-off-by: Jiri Slaby Signed-off-by: Greg Kroah-Hartman --- arch/x86/net/bpf_jit_comp.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) --- a/arch/x86/net/bpf_jit_comp.c +++ b/arch/x86/net/bpf_jit_comp.c @@ -176,7 +176,12 @@ void bpf_jit_compile(struct sk_filter *f } cleanup_addr = proglen; /* epilogue address */ - for (pass = 0; pass < 10; pass++) { + /* JITed image shrinks with every pass and the loop iterates + * until the image stops shrinking. Very large bpf programs + * may converge on the last pass. In such case do one more + * pass to emit the final image + */ + for (pass = 0; pass < 10 || image; pass++) { u8 seen_or_pass0 = (pass == 0) ? (SEEN_XREG | SEEN_DATAREF | SEEN_MEM) : seen; /* no prologue/epilogue for trivial filters (RET something) */ proglen = 0; Patches currently in stable-queue which might be from ast@plumgrid.com are queue-3.10/x86-bpf_jit-fix-compilation-of-large-bpf-programs.patch