From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from www62.your-server.de (www62.your-server.de [213.133.104.62]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 77BAB3BE65C for ; Fri, 29 May 2026 09:41:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=213.133.104.62 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780047686; cv=none; b=LijwR6KF7jhlft36xQDzI8c50gjfLmimJc0bx9G+rB1+wHMe9LIrx0FMDgUXLnvMVstudjTZmIpi/BoGAwAg/ck3aUNQwM9kQsIqEwEHedPVN7/rCzYi5WTfpJPocUep8qjY+jR5pXiZalQ+Z6uAlUbkcoiIX/H0ZvKTWVof1oI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780047686; c=relaxed/simple; bh=dYiZMuGREOuwutJRNvMw7V199/hazG1JPPCNc9kTwzU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=slUDi21iSjW+DPHZ3/RF75foQG0imKUAPkr9j2fq8mcChM6ySCi0JvpmFmLjyLvSZxYn/9wHikazNsLzUhv62NYsmR350a/m6ycpjrPQmGQ6Wy4FHDjIFcqWQvhNF+v7gZ3hgJvotBe57/LOupGPtPjFg1jCIe5aI3EXCzi+FA8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=iogearbox.net; spf=pass smtp.mailfrom=iogearbox.net; dkim=pass (2048-bit key) header.d=iogearbox.net header.i=@iogearbox.net header.b=nKWT7dc6; arc=none smtp.client-ip=213.133.104.62 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=iogearbox.net Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=iogearbox.net Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=iogearbox.net header.i=@iogearbox.net header.b="nKWT7dc6" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=iogearbox.net; s=default2302; h=Content-Transfer-Encoding:MIME-Version: References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From:Sender:Reply-To: Content-Type:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID; bh=4MzxppZazcORgS9qzj0W2Up9gfPh56EM67N95ZlyBzA=; b=nKWT7dc6TRH/Jgdb33w/E6JUyQ 7Kh3Gu8s1G6SzM14mdtYZ43Dyn355OOMZrGbfuQk85TbOvXP5E5AJOj+wxV/K+bqhLwQk9trKbCEN LLQh3FT5yZZl62e2msz5YyiP/btH6qZeUjS9eBZiNMNn6IUp7QPKR53zTeiLimGdKFArLqjHnhbjd RhpBWG9ZwXLV2nDyV5Slp/GbB+F7x20CLuiu1/uZR0SgR5EVQ/TfIMIjXUqQtsW0JNk4T719FATiI gxVXkHCQoXRnSRIxM6pdViXBs0N9Y5BJ0Re9QsRNpfuk/KWyejTt0NBohIVd08Oa/UblEYaXNFgVM 1rftlNYg==; Received: from localhost ([127.0.0.1]) by www62.your-server.de with esmtpsa (TLS1.3) tls TLS_AES_256_GCM_SHA384 (Exim 4.96.2) (envelope-from ) id 1wStiS-000LAN-1p; Fri, 29 May 2026 11:41:20 +0200 From: Daniel Borkmann To: kpsingh@kernel.org Cc: bpf@vger.kernel.org, sashiko Subject: [PATCH bpf-next 2/3] libbpf: Skip hash computation when loader generation failed Date: Fri, 29 May 2026 11:41:17 +0200 Message-ID: <20260529094119.307264-2-daniel@iogearbox.net> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260529094119.307264-1-daniel@iogearbox.net> References: <20260529094119.307264-1-daniel@iogearbox.net> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Virus-Scanned: Clear (ClamAV 1.4.3/28015/Fri May 29 08:24:51 2026) bpf_gen__finish() calls compute_sha_update_offsets() gated only on the gen_hash option, without first consulting gen->error. On a failed generation this is buggy: a failed realloc_data_buf() sets gen->data_start to NULL (leaving gen->data_cur dangling), so compute_sha_update_offsets() runs libbpf_sha256() over a NULL buffer with a bogus length; a failed realloc_insn_buf() likewise sets gen->insn_start to NULL and the hash immediates get patched through that NULL base. The computed program is discarded in either case, since the following "if (!gen->error)" block does not publish opts->insns once an error is set. Thus, skip the hash pass when generation has already failed. Fixes: ea923080c145 ("libbpf: Embed and verify the metadata hash in the loader") Reported-by: sashiko Signed-off-by: Daniel Borkmann --- tools/lib/bpf/gen_loader.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/tools/lib/bpf/gen_loader.c b/tools/lib/bpf/gen_loader.c index 7b95ced7bcba..3a6e1d53f287 100644 --- a/tools/lib/bpf/gen_loader.c +++ b/tools/lib/bpf/gen_loader.c @@ -397,13 +397,12 @@ int bpf_gen__finish(struct bpf_gen *gen, int nr_progs, int nr_maps) blob_fd_array_off(gen, i)); emit(gen, BPF_MOV64_IMM(BPF_REG_0, 0)); emit(gen, BPF_EXIT_INSN()); - if (OPTS_GET(gen->opts, gen_hash, false)) - compute_sha_update_offsets(gen); - - pr_debug("gen: finish %s\n", errstr(gen->error)); if (!gen->error) { struct gen_loader_opts *opts = gen->opts; + if (OPTS_GET(opts, gen_hash, false)) + compute_sha_update_offsets(gen); + opts->insns = gen->insn_start; opts->insns_sz = gen->insn_cur - gen->insn_start; opts->data = gen->data_start; @@ -418,6 +417,7 @@ int bpf_gen__finish(struct bpf_gen *gen, int nr_progs, int nr_maps) bpf_insn_bswap(insn++); } } + pr_debug("gen: finish %s\n", errstr(gen->error)); return gen->error; } -- 2.43.0