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 99FF23164C3; Wed, 20 May 2026 16:52:45 +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=1779295967; cv=none; b=W8WnVCt17ezUBhL1CXhR2snc2eq7uqtqmygZhf9x7ak8AIFw18PXGhy9slczAS+W+oC0ceZJgI/utXjlSng9UXeHY5c4rDy28GXWgKEqIB+8z7QRdJqvOZAi8QKZxFNBaGAt7Ao4ZM9C7GnNfF+mpUuySwWxEocF1UT/QFjaZy0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779295967; c=relaxed/simple; bh=fdfTdRsPaXVW3izBwBkg2ekwAd0p/5RSQtCH8vQmqW4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=QJpzQ909b/pzTw039bMDYqxH+qv5JjfNnOnUsS1h2dUJKWY4seEdve1QBj5jK9eTd2LrftL0TV1LVidUQlRxtm6mXusK9drMJvdwdIeKUD8hMzApQ0+IyJE0gYFrVS6IbYm4OW2WOnZZRCUh89PeDueov1mjp+uJnvxeiqFba6M= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=N0///RvU; 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="N0///RvU" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0E1771F000E9; Wed, 20 May 2026 16:52:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1779295965; bh=ye4rkb6hjL+aWyMcm7i1iTSr4ezxxMxqtoLcauahVCg=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=N0///RvUULS8tjeg2tVgveF4uwQitOECBv6LpzV1NFiA8SoyGMxVnsIkr+lZCLNck CCnNwTdCikkaynuz8VocQ+51GYzcd4MJL3ByqIYW6+BoUg69CtySak5z25iHTXyTQ0 MOHdTWYlErXHQjwbPdMLvA9lvL2JJSCAGvrCg/Hw= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Daniel Borkmann , Jonas Rebmann , Puranjay Mohan , Emil Tsalapatis , Alexei Starovoitov , Sasha Levin Subject: [PATCH 7.0 0621/1146] bpf, arm32: Reject BPF-to-BPF calls and callbacks in the JIT Date: Wed, 20 May 2026 18:14:31 +0200 Message-ID: <20260520162202.238323234@linuxfoundation.org> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260520162148.390695140@linuxfoundation.org> References: <20260520162148.390695140@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 7.0-stable review patch. If anyone has any objections, please let me know. ------------------ From: Puranjay Mohan [ Upstream commit e1d486445af3c392628532229f7ce5f5cf7891b6 ] The ARM32 BPF JIT does not support BPF-to-BPF function calls (BPF_PSEUDO_CALL) or callbacks (BPF_PSEUDO_FUNC), but it does not reject them either. When a program with subprograms is loaded (e.g. libxdp's XDP dispatcher uses __noinline__ subprograms, or any program using callbacks like bpf_loop or bpf_for_each_map_elem), the verifier invokes bpf_jit_subprogs() which calls bpf_int_jit_compile() for each subprogram. For BPF_PSEUDO_CALL, since ARM32 does not reject it, the JIT silently emits code using the wrong address computation: func = __bpf_call_base + imm where imm is a pc-relative subprogram offset, producing a bogus function pointer. For BPF_PSEUDO_FUNC, the ldimm64 handler ignores src_reg and loads the immediate as a normal 64-bit value without error. In both cases, build_body() reports success and a JIT image is allocated. ARM32 lacks the jit_data/extra_pass mechanism needed for the second JIT pass in bpf_jit_subprogs(). On the second pass, bpf_int_jit_compile() performs a full fresh compilation, allocating a new JIT binary and overwriting prog->bpf_func. The first allocation is never freed. bpf_jit_subprogs() then detects the function pointer changed and aborts with -ENOTSUPP, but the original JIT binary has already been leaked. Each program load/unload cycle leaks one JIT binary allocation, as reported by kmemleak: unreferenced object 0xbf0a1000 (size 4096): backtrace: bpf_jit_binary_alloc+0x64/0xfc bpf_int_jit_compile+0x14c/0x348 bpf_jit_subprogs+0x4fc/0xa60 Fix this by rejecting both BPF_PSEUDO_CALL in the BPF_CALL handler and BPF_PSEUDO_FUNC in the BPF_LD_IMM64 handler, falling through to the existing 'notyet' path. This causes build_body() to fail before any JIT binary is allocated, so bpf_int_jit_compile() returns the original program unjitted. bpf_jit_subprogs() then sees !prog->jited and cleanly falls back to the interpreter with no leak. Acked-by: Daniel Borkmann Fixes: 1c2a088a6626 ("bpf: x64: add JIT support for multi-function programs") Reported-by: Jonas Rebmann Closes: https://lore.kernel.org/bpf/b63e9174-7a3d-4e22-8294-16df07a4af89@pengutronix.de Tested-by: Jonas Rebmann Signed-off-by: Puranjay Mohan Reviewed-by: Emil Tsalapatis Link: https://lore.kernel.org/r/20260417143353.838911-1-puranjay@kernel.org Signed-off-by: Alexei Starovoitov Signed-off-by: Sasha Levin --- arch/arm/net/bpf_jit_32.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/arch/arm/net/bpf_jit_32.c b/arch/arm/net/bpf_jit_32.c index deeb8f292454b..a900aa9738855 100644 --- a/arch/arm/net/bpf_jit_32.c +++ b/arch/arm/net/bpf_jit_32.c @@ -1852,6 +1852,9 @@ static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx) { u64 val = (u32)imm | (u64)insn[1].imm << 32; + if (insn->src_reg == BPF_PSEUDO_FUNC) + goto notyet; + emit_a32_mov_i64(dst, val, ctx); return 1; @@ -2055,6 +2058,9 @@ static int build_insn(const struct bpf_insn *insn, struct jit_ctx *ctx) const s8 *r5 = bpf2a32[BPF_REG_5]; const u32 func = (u32)__bpf_call_base + (u32)imm; + if (insn->src_reg == BPF_PSEUDO_CALL) + goto notyet; + emit_a32_mov_r64(true, r0, r1, ctx); emit_a32_mov_r64(true, r1, r2, ctx); emit_push_r64(r5, ctx); -- 2.53.0