From nobody Mon Sep 28 20:09:07 2026 Received: from oss.cyber.gouv.fr (oss.cyber.gouv.fr [51.159.188.251]) (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 74EE73BED7A; Mon, 17 Aug 2026 20:49:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=51.159.188.251 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786999748; cv=none; b=GBW5su6WeBbH/VXyxSsUGSnjCrYYf5DwyUrYTA4pPRTxqxoN4Orcy8Q5/V55/vF8sJpwSVQzsYSjyjQjZLUj6IWjN9Og1bHPWpM0EBB8L6iMHjC9od/+Z8jBKqsJoRu3BYvAN+NAmQPuo0DnR8JphmzdNg7fO+XcfLhMSmiABmQ= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786999748; c=relaxed/simple; bh=glOUblceaLvI7ca7icF5rrafZtiHEer7PTjtN+3Li6c=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=o2glJUB2Crma8OMgUzWUmWL1d3tZpDTsBRmPSFdpOvieUyR17bOiEibhCp1ymYs1d9xYR3Y268QZwRrq2yBUgS/+7vwIVEDVZnZGVz3x2tHc5Sd6NNCtNK7xXhbZuJp57kPxFNHgUqlIi8O+O2KRBHHAbOEuHaSqYAktcew2bb8= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=oss.cyber.gouv.fr; spf=pass smtp.mailfrom=oss.cyber.gouv.fr; dkim=pass (2048-bit key) header.d=oss.cyber.gouv.fr header.i=@oss.cyber.gouv.fr header.b=C/EAmr7W; arc=none smtp.client-ip=51.159.188.251 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=oss.cyber.gouv.fr Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=oss.cyber.gouv.fr Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=oss.cyber.gouv.fr header.i=@oss.cyber.gouv.fr header.b="C/EAmr7W" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=oss.cyber.gouv.fr; s=default; h=Content-Transfer-Encoding:Content-Type: MIME-Version:References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From:Sender :Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help: List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=FAGUgTLVVxhP85fTHj7eiWn2oMK1HrsMNU8JsUjGXBg=; b=C/EAmr7WlOgy1DRgNSIfY57U/M eJPPI/WpegRtsKsp10VrM7uebhmFL6VxxygnJqnXg14Y6+x6PxT1YcmCk63mebU2Y6c/6JaQ+fEOG M21/Bbx76yywH/vKjEzADmlr/V8oD1RiczWYHBTMpIlSHfDlycFYy88GcidVyHeF9CrtOjYG1i3Yr /pj+dTB7H2gPTpCAHWY+q+aW8HjE5klCcWnrOSerEfaR1U6wWfJs9+itnMEgvJWdaomqWYddkzUpv unLGVEaHLt8dfc/ZJLEzgES+swysyw2Aq+DJFFhsPC8DUrJju+RC/VcPy/l6M89pRwH3cFX/xyqML PRtKw6Nw==; Received: from [151.115.150.205] (port=43084 helo=gepetto..) by pf-012.whm.fr-par.scw.cloud with esmtpsa (TLS1.3) tls TLS_AES_256_GCM_SHA384 (Exim 4.99.5) (envelope-from ) id 1ww4GP-0000000CoBp-1uyh; Mon, 17 Aug 2026 22:48:57 +0200 From: =?UTF-8?q?J=C3=A9r=C3=A9my=20Jean?= To: Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Eduard Zingerman , Kumar Kartikeya Dwivedi , Yonghong Song Cc: bpf@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, =?UTF-8?q?J=C3=A9r=C3=A9my=20Jean?= Subject: [PATCH v2 1/2] bpf: reject stack-argument callback subprograms Date: Mon, 17 Aug 2026 20:48:11 +0000 Message-ID: <20260817204812.1637171-2-Jeremy.Jean@oss.cyber.gouv.fr> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260817204812.1637171-1-Jeremy.Jean@oss.cyber.gouv.fr> References: <20260817204812.1637171-1-Jeremy.Jean@oss.cyber.gouv.fr> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - pf-012.whm.fr-par.scw.cloud X-AntiAbuse: Original Domain - vger.kernel.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - oss.cyber.gouv.fr X-Get-Message-Sender-Via: pf-012.whm.fr-par.scw.cloud: authenticated_id: jeremy.jean@oss.cyber.gouv.fr X-Authenticated-Sender: pf-012.whm.fr-par.scw.cloud: jeremy.jean@oss.cyber.gouv.fr X-Source: X-Source-Args: X-Source-Dir: Helper callbacks enter BPF subprograms through bpf_callback_t, whose runtime ABI supplies five arguments. BTF validation nevertheless permits static callback subprograms to declare more than five arguments when JIT stack arguments are supported. This lets verifier state for a callback use outgoing stack argument slots prepared at the helper call site. The helper does not pass those slots. On x86-64, callback loads of arguments seven and later therefore read the helper native frame instead of the synthetic values checked by the verifier. KASAN reports a slab OOB write. Reject callback subprograms with incoming stack arguments when processing callback calls. Fixes: 0f6bd5e7a804 ("bpf: Support stack arguments for bpf functions") Assisted-by: Codex:gpt-5 Signed-off-by: J=C3=A9r=C3=A9my Jean --- kernel/bpf/verifier.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index fdc5fbb1f78c..5fcefc0eaba0 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -9285,6 +9285,8 @@ static int push_callback_call(struct bpf_verifier_env= *env, struct bpf_insn *ins err =3D btf_check_subprog_call(env, subprog, caller->regs); if (err =3D=3D -EFAULT) return err; + if (bpf_in_stack_arg_cnt(&env->subprog_info[subprog])) + return -EINVAL; =20 /* set_callee_state is used for direct subprog calls, but we are * interested in validating only BPF helpers that can call subprogs as --=20 2.47.3 From nobody Mon Sep 28 20:09:07 2026 Received: from oss.cyber.gouv.fr (oss.cyber.gouv.fr [51.159.188.251]) (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 E52A63BED66; 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arc=none smtp.client-ip=51.159.188.251 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=oss.cyber.gouv.fr Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=oss.cyber.gouv.fr Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=oss.cyber.gouv.fr header.i=@oss.cyber.gouv.fr header.b="OtWxUuWl" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=oss.cyber.gouv.fr; s=default; h=Content-Transfer-Encoding:Content-Type: MIME-Version:References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From:Sender :Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help: List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=ixMF7r8hV0lzYA6CsB9yjlSEeIxuTJm60sYPclnVrsM=; b=OtWxUuWl57d2kgc/pmTQKXH3K4 OGh7+wbS5MfnewwXt7EnqLr+FOk8MOP4Zi3bn2SmzkxGFtoHN0IyinkgtzKbe1gr85XL6szxq+4w3 SaQzzxPG1ss0fRBU7P0EEeQGnHtavfS+7CGKXaIyKbHM3AIHL1qO5FRoAAlgIQTaaXeEQ8KWDPcvV MLaANPsO9oxzNFRf2Z9XXpbCE1B39fZmsN8iLeHWZsItEmfnL4xxCK9HPIMkVPAriAReqfGjPpo7v NHxJjnpkyLYK3ZltPL5Vfqxyqxb1B1am8WvXibZaKHDmpySujZW5ElcQfDeXHKJLKbgtyjKcCTdDh 0daSGDWQ==; Received: from [151.115.150.205] (port=43084 helo=gepetto..) by pf-012.whm.fr-par.scw.cloud with esmtpsa (TLS1.3) tls TLS_AES_256_GCM_SHA384 (Exim 4.99.5) (envelope-from ) id 1ww4GS-0000000CoBp-0XNY; Mon, 17 Aug 2026 22:48:59 +0200 From: =?UTF-8?q?J=C3=A9r=C3=A9my=20Jean?= To: Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Eduard Zingerman , Kumar Kartikeya Dwivedi , Yonghong Song Cc: bpf@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, =?UTF-8?q?J=C3=A9r=C3=A9my=20Jean?= Subject: [PATCH v2 2/2] selftests/bpf: add callback stack-argument rejection test Date: Mon, 17 Aug 2026 20:48:12 +0000 Message-ID: <20260817204812.1637171-3-Jeremy.Jean@oss.cyber.gouv.fr> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260817204812.1637171-1-Jeremy.Jean@oss.cyber.gouv.fr> References: <20260817204812.1637171-1-Jeremy.Jean@oss.cyber.gouv.fr> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - pf-012.whm.fr-par.scw.cloud X-AntiAbuse: Original Domain - vger.kernel.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - oss.cyber.gouv.fr X-Get-Message-Sender-Via: pf-012.whm.fr-par.scw.cloud: authenticated_id: jeremy.jean@oss.cyber.gouv.fr X-Authenticated-Sender: pf-012.whm.fr-par.scw.cloud: jeremy.jean@oss.cyber.gouv.fr X-Source: X-Source-Args: X-Source-Dir: Add verifier coverage for callback subprograms that declare incoming stack arguments. The test passes a nine-argument callback to bpf_loop() and expects the verifier to reject it. Assisted-by: Codex:gpt-5 Signed-off-by: J=C3=A9r=C3=A9my Jean --- .../selftests/bpf/progs/verifier_stack_arg.c | 32 +++++++++++++++++++ 1 file changed, 32 insertions(+) diff --git a/tools/testing/selftests/bpf/progs/verifier_stack_arg.c b/tools= /testing/selftests/bpf/progs/verifier_stack_arg.c index 7e0ce5db28a0..50b276fc2c3f 100644 --- a/tools/testing/selftests/bpf/progs/verifier_stack_arg.c +++ b/tools/testing/selftests/bpf/progs/verifier_stack_arg.c @@ -27,6 +27,13 @@ static int subprog_7args(int a, int b, int c, int d, int= e, int f, int g) return a + b + c + d + e + f + g; } =20 +__noinline __used +static int callback_9args(__u32 index, void *ctx, long a3, long a4, + long a5, long a6, long a7, long a8, long a9) +{ + return a9; +} + __noinline __used static long subprog_deref_arg6(long a, long b, long c, long d, long e, lon= g *f) { @@ -79,6 +86,31 @@ __naked void stack_arg_two_subprogs(void) ); } =20 +SEC("tc") +__description("stack_arg: callback with incoming stack args") +__failure +__naked void stack_arg_callback_many_args(void) +{ + asm volatile ( + "r6 =3D 0;" + "*(u64 *)(r11 - 32) =3D 0;" + "*(u64 *)(r11 - 24) =3D 0;" + "*(u64 *)(r11 - 16) =3D 0;" + "*(u64 *)(r11 - 8) =3D 0;" + "r1 =3D 1;" + "r2 =3D %[callback_9args];" + "r3 =3D 0;" + "r4 =3D 0;" + "call %[bpf_loop];" + "r0 =3D 0;" + "exit;" + : + : __imm_ptr(callback_9args), + __imm(bpf_loop) + : __clobber_common, "r6" + ); +} + SEC("tc") __description("stack_arg: read from uninitialized stack arg slot") __failure --=20 2.47.3