From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 A727A402434; Thu, 12 Mar 2026 20:13:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773346420; cv=none; b=uHVlVfCxcKirfk+7cn1Cxsp7xuOghn4qoc3HXcKK5as54f9yC5F5Xl9446ps9vn35K+4amFrz5ad6IQ6Q2bPq49h8k08Tapfjo1bvR3ejK+jR8lzzRLmNLp3ebkOMzbFCL/ioK3lqaX+GOlRypu3QAMxMdGsdmqE4VnISX/gAzQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1773346420; c=relaxed/simple; bh=/0tQTpSTObsUW+WDS0uRTmV2ydNMJlNtwv6QY5z0VZM=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=jrjys1+6S3FF4iroMvkokJoMV3ts1fArXEYSIP/jJPxs/UGpbA1nJdnpUvQT2U2VF6YGJCuPyydQ0fOQgG+fVf/lhFAcEnf9ypbdGLPr9iIrDib0hIlI5SnYd+VOR6g74MG7YDuQHBeJEe6U4v0tGRg+GJPgbXD8StJHAtrkKok= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=SQ8yL3zI; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="SQ8yL3zI" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B156DC19425; Thu, 12 Mar 2026 20:13:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1773346420; bh=/0tQTpSTObsUW+WDS0uRTmV2ydNMJlNtwv6QY5z0VZM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=SQ8yL3zI9iSPYmUTHpGg+t7zs1/zNX6hc7+a6VJWUSvqa44Bx6wRUnYOjVXAayjp2 wCP97WPtyhHGSzWXlaA+nhPCvXtEww9+8nMPDXQylnHz3q1TMzfpeztke1rrj9731d My2MyYkk3J6Vq1Sr7hJpW8vmi8/3RQyhCipavoR8= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Fuad Tabba , Will Deacon , Alexei Starovoitov , Sasha Levin Subject: [PATCH 6.12 038/265] bpf, arm64: Force 8-byte alignment for JIT buffer to prevent atomic tearing Date: Thu, 12 Mar 2026 21:07:05 +0100 Message-ID: <20260312201019.570238335@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260312201018.128816016@linuxfoundation.org> References: <20260312201018.128816016@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Fuad Tabba [ Upstream commit ef06fd16d48704eac868441d98d4ef083d8f3d07 ] struct bpf_plt contains a u64 target field. Currently, the BPF JIT allocator requests an alignment of 4 bytes (sizeof(u32)) for the JIT buffer. Because the base address of the JIT buffer can be 4-byte aligned (e.g., ending in 0x4 or 0xc), the relative padding logic in build_plt() fails to ensure that target lands on an 8-byte boundary. This leads to two issues: 1. UBSAN reports misaligned-access warnings when dereferencing the structure. 2. More critically, target is updated concurrently via WRITE_ONCE() in bpf_arch_text_poke() while the JIT'd code executes ldr. On arm64, 64-bit loads/stores are only guaranteed to be single-copy atomic if they are 64-bit aligned. A misaligned target risks a torn read, causing the JIT to jump to a corrupted address. Fix this by increasing the allocation alignment requirement to 8 bytes (sizeof(u64)) in bpf_jit_binary_pack_alloc(). This anchors the base of the JIT buffer to an 8-byte boundary, allowing the relative padding math in build_plt() to correctly align the target field. Fixes: b2ad54e1533e ("bpf, arm64: Implement bpf_arch_text_poke() for arm64") Signed-off-by: Fuad Tabba Acked-by: Will Deacon Link: https://lore.kernel.org/r/20260226075525.233321-1-tabba@google.com Signed-off-by: Alexei Starovoitov Signed-off-by: Sasha Levin --- arch/arm64/net/bpf_jit_comp.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/arm64/net/bpf_jit_comp.c b/arch/arm64/net/bpf_jit_comp.c index 82b57436f2f10..9310196e0a09e 100644 --- a/arch/arm64/net/bpf_jit_comp.c +++ b/arch/arm64/net/bpf_jit_comp.c @@ -1880,7 +1880,7 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog) extable_offset = round_up(prog_size + PLT_TARGET_SIZE, extable_align); image_size = extable_offset + extable_size; ro_header = bpf_jit_binary_pack_alloc(image_size, &ro_image_ptr, - sizeof(u32), &header, &image_ptr, + sizeof(u64), &header, &image_ptr, jit_fill_hole); if (!ro_header) { prog = orig_prog; -- 2.51.0