From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 6611F3C0601; Sat, 17 Oct 2026 17:33:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792258384; cv=none; b=soSK+U6Yac7qN7eqhM9QouB5ccsCnhIrSkK9aaagRx2ZVFRTLEiXCaSJ4eCmPWii+wDS8xzWjFCyXRP4sv3rI0tEOamLMdftmaTurjebqa1uj9lPbBbCIJ+5Jg6FdQj5hK+G4vl+Gic2PYj2HMNQCDH8aMZFzHgC8GdcXWmy9sc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792258384; c=relaxed/simple; bh=vYry0dLdfOLjFvD0+cYFp5psKo2QAGgdDZutKOiOkaI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Hqg7FHF10/2ENwky/u//7Zorw+8blO8qylJ7tKriqPIShGzazq86VlUrwLhrBiaIvBHhrd5LIzhKryfUfcsB5KSk+aiZSJ195L9ZQ5vt6clZN+BDujE/63b4Sc1pnEQhw3THA6mK1EcktZ8ITw8+HZmhcEqCkRQoF1vaI/dqlyA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=Yo/eRVNP; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="Yo/eRVNP" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A895D1F000C6; Sat, 17 Oct 2026 17:33:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1792258383; bh=LxrkoEi1aDJbfP90aOEjh46LzBUyWnhTUIrlcAr0C5Q=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=Yo/eRVNPKdVp8PGNuRdWnj68pZcvPwLaUmNio2Pc4cgYopiibae8mRRSLCAOlQ0qi YqksqGUam6VvQcgiOuq8E+/1g6VoERazm4m9h57KcYko4wsQEhEcmrsga1EjMsQRUC p3t2C1EJUtr9leGlTRngINYAXicGRbqIPOhR9XYg= 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 6.6 0866/1674] bpf, arm64: Force 8-byte alignment for JIT buffer to prevent atomic tearing Date: Sat, 17 Oct 2026 17:52:18 +0200 Message-ID: <20261017160453.343123376@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261017160431.119607952@linuxfoundation.org> References: <20261017160431.119607952@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-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 1fcdb129ada8a..f562060a50c4e 100644 --- a/arch/arm64/net/bpf_jit_comp.c +++ b/arch/arm64/net/bpf_jit_comp.c @@ -1648,7 +1648,7 @@ 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; header = bpf_jit_binary_alloc(image_size, &image_ptr, - sizeof(u32), jit_fill_hole); + sizeof(u64), jit_fill_hole); if (header == NULL) { prog = orig_prog; goto out_off; -- 2.53.0