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 992E325A341; Tue, 11 Nov 2025 01:02:00 +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=1762822923; cv=none; b=TgMw3seGGvwehdileNGzaJX9INbAOkE9rF0c/yTLU2HzRF9P45bU9LuAl4BiyF2A5kwvayVvMPqbJzJW0jaWNhMoxYp3rqhXveC2hb/ve2LKOiGjlMqjbafJ6ieuXjcuyH5mXKwGscFG75XpfzHQjHoxSLoyDtKyQH2JoBB41uA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762822923; c=relaxed/simple; bh=y2TYIee4cIKgFCP4HIesO6yE+eqzUzXQ2x3nIR5cW5s=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=cK6WLQTB30ZQBZcExd6ruqPIADMiKr9VBZfSl2D5BkenHz/w9j2+oAnZvwTykaqO3v2ACLN1ILxfeGsk0fqa4pxqTFQJpV6Goq3Ut+MrrLl0iauwE4WG5kxPx1CzM+dZfdSafmnmI8Tm7hOad03h5r1dE7RWVPCNtiAFDqXPkLU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=miCDmc7x; 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="miCDmc7x" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9FE8CC16AAE; Tue, 11 Nov 2025 01:01:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1762822919; bh=y2TYIee4cIKgFCP4HIesO6yE+eqzUzXQ2x3nIR5cW5s=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=miCDmc7xQmxIWtBQoAGvjtsCBQX81sxDk5RcNXqa3jsvlQKZDxu/CAnKb857JRNwY k8YjObMpIa/oS4Fpd6tG1HQOfRuo2W7wCFwbBnRQ5zzVLSdLo6zAb6mcIq1suqLJnX SrEFHstleb3b1H4WoEblS5PkJrLn7VdsG60Eam+Y= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Eduard Zingerman , Yonghong Song , Alexei Starovoitov , Sasha Levin Subject: [PATCH 6.17 196/849] selftests/bpf: Fix selftest verifier_arena_large failure Date: Tue, 11 Nov 2025 09:36:06 +0900 Message-ID: <20251111004541.179986684@linuxfoundation.org> X-Mailer: git-send-email 2.51.2 In-Reply-To: <20251111004536.460310036@linuxfoundation.org> References: <20251111004536.460310036@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 6.17-stable review patch. If anyone has any objections, please let me know. ------------------ From: Yonghong Song [ Upstream commit 5a427fddec5e76360725a0f03df3a2a003efbe2e ] With latest llvm22, I got the following verification failure: ... ; int big_alloc2(void *ctx) @ verifier_arena_large.c:207 0: (b4) w6 = 1 ; R6_w=1 ... ; if (err) @ verifier_arena_large.c:233 53: (56) if w6 != 0x0 goto pc+62 ; R6=0 54: (b7) r7 = -4 ; R7_w=-4 55: (18) r8 = 0x7f4000000000 ; R8_w=scalar() 57: (bf) r9 = addr_space_cast(r8, 0, 1) ; R8_w=scalar() R9_w=arena 58: (b4) w6 = 5 ; R6_w=5 ; pg = page[i]; @ verifier_arena_large.c:238 59: (bf) r1 = r7 ; R1_w=-4 R7_w=-4 60: (07) r1 += 4 ; R1_w=0 61: (79) r2 = *(u64 *)(r9 +0) ; R2_w=scalar() R9_w=arena ; if (*pg != i) @ verifier_arena_large.c:239 62: (bf) r3 = addr_space_cast(r2, 0, 1) ; R2_w=scalar() R3_w=arena 63: (71) r3 = *(u8 *)(r3 +0) ; R3_w=scalar(smin=smin32=0,smax=umax=smax32=umax32=255,var_off=(0x0; 0xff)) 64: (5d) if r1 != r3 goto pc+51 ; R1_w=0 R3_w=0 ; bpf_arena_free_pages(&arena, (void __arena *)pg, 2); @ verifier_arena_large.c:241 65: (18) r1 = 0xff11000114548000 ; R1_w=map_ptr(map=arena,ks=0,vs=0) 67: (b4) w3 = 2 ; R3_w=2 68: (85) call bpf_arena_free_pages#72675 ; 69: (b7) r1 = 0 ; R1_w=0 ; page[i + 1] = NULL; @ verifier_arena_large.c:243 70: (7b) *(u64 *)(r8 +8) = r1 R8 invalid mem access 'scalar' processed 61 insns (limit 1000000) max_states_per_insn 0 total_states 6 peak_states 6 mark_read 2 ============= #489/5 verifier_arena_large/big_alloc2:FAIL The main reason is that 'r8' in insn '70' is not an arena pointer. Further debugging at llvm side shows that llvm commit ([1]) caused the failure. For the original code: page[i] = NULL; page[i + 1] = NULL; the llvm transformed it to something like below at source level: __builtin_memset(&page[i], 0, 16) Such transformation prevents llvm BPFCheckAndAdjustIR pass from generating proper addr_space_cast insns ([2]). Adding support in llvm BPFCheckAndAdjustIR pass should work, but not sure that such a pattern exists or not in real applications. At the same time, simply adding a memory barrier between two 'page' assignment can fix the issue. [1] https://github.com/llvm/llvm-project/pull/155415 [2] https://github.com/llvm/llvm-project/pull/84410 Cc: Eduard Zingerman Signed-off-by: Yonghong Song Link: https://lore.kernel.org/r/20250920045805.3288551-1-yonghong.song@linux.dev Signed-off-by: Alexei Starovoitov Signed-off-by: Sasha Levin --- tools/testing/selftests/bpf/progs/verifier_arena_large.c | 1 + 1 file changed, 1 insertion(+) diff --git a/tools/testing/selftests/bpf/progs/verifier_arena_large.c b/tools/testing/selftests/bpf/progs/verifier_arena_large.c index 9dbdf123542d3..f19e15400b3e1 100644 --- a/tools/testing/selftests/bpf/progs/verifier_arena_large.c +++ b/tools/testing/selftests/bpf/progs/verifier_arena_large.c @@ -240,6 +240,7 @@ int big_alloc2(void *ctx) return 5; bpf_arena_free_pages(&arena, (void __arena *)pg, 2); page[i] = NULL; + barrier(); page[i + 1] = NULL; cond_break; } -- 2.51.0