From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pl1-f201.google.com (mail-pl1-f201.google.com [209.85.214.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A004A156CA for ; Sat, 29 Mar 2025 00:03:53 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1743206635; cv=none; b=M69sMcV5BOs+Gpp423EonRSPVEhHbfqJXhXccg++YyieNSPR7dm0f8PG2qQUdw/nT3Vh/qwCngGt2yEmu4/FfOZ/bb7/VMgEwgLJ26zgj/51A6e0irco34q8RvKP/QgqhxEkg+9xc3YnuIX/ALrTysuvTcbaJ2cNowvAN67Uq0k= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1743206635; c=relaxed/simple; bh=0GH03YEIRBHpcTs5EQTf5tRjGOZhfj5ycrE7WqRiMdo=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=duOnLrHc2PeDn7ZAIXa8kehSEj37MJDgE6IxyepmbNdlZnnC7i/T027Z4bXAI/t4qZmnlF4EGG1Hdrb9uWXSHNoP947Ym0VYDi79kmrfZIgtreM6q5ct3v4tF+D+XkwFfmuAwk/PuF8gsI6Qm9xzI9Qp1+FTwXQVWmUIfiz18nc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--pcc.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=uRxFww+t; arc=none smtp.client-ip=209.85.214.201 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--pcc.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="uRxFww+t" Received: by mail-pl1-f201.google.com with SMTP id d9443c01a7336-2241ae15dcbso57944825ad.0 for ; Fri, 28 Mar 2025 17:03:53 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1743206633; x=1743811433; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=tGMonBDCtHbGxccj+//vlpjOsUsbEFJEDLrw6ctd8aw=; b=uRxFww+tlYNsYYB/x9abq3jT5BxzIRaJUYOfFllDJWB4ChJ2ynmwPT58DCh+oCPC0f /AGtzjTIL16uwwjjac9W8WKj80GqUMTR5U1Xa/JL30HNwCzN5Po2ReqW2JpYsah1BT2X bV8C99W9UuKAtbUgsJC7arwnbsTmvOGe756H+JQRtw4tjfrCt1x266jtMuPNkHFGiHbl 7x6Vbij036Kgwn5V/vxuKXks11Dp5feiddn8rEQm0WKaHjof3tqdLL06kTtbUii6avWh 3W+hnXJbZuIKCGnefvmF6gOIlJDLYDlTeb2dvCXoJUYH1p8xRfAGuBdTe6rV/sosUQWE KUbg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1743206633; x=1743811433; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=tGMonBDCtHbGxccj+//vlpjOsUsbEFJEDLrw6ctd8aw=; b=K+Y2imFfH7xPZA3jjEJOiAkmlxBqaG5xAL13E0wkGtRtYaz/JN91Jus1m/gtEpXRO0 lQGbM2pIBAZ/MelvEi7DtwQCpNnej3MxnQNiIZDEDWcYcZR7O7Bm2poe8xF3A7HCNHfy xA6oIoXEGM62pCB/R0ZE1QU7gFxJ2VvuDoYzh346Vl4Csgi5Of/wGislW7eqxR/+bPof L+5oN+zWB/LKlTGSsJ3NT8BrugkHXdEbXHDQxj9uvF3Pi7SJJHqrgLK0UylF0WNQZn+Q AwHrV7mc9Uk4/5MIrLY+sApslVcVZrkV3NPAJEINuhERxMENwTRN2+cAhwV3QWy/sbcP ov+g== X-Forwarded-Encrypted: i=1; AJvYcCXcltsRpWjkHugdqIhEtSSYGQg/lmPsXfdixsMVr8cDF/KfLUpXj1dFEefNwApXbDKS7A/dmydLb75ZxIxIZkI=@vger.kernel.org X-Gm-Message-State: AOJu0Yz/UtvemaY8C3pRHK3/+e9yeWEpFcChfjxXJvucNr8/nMPnylSh ehjjy2oAZ7NKzxttd2I2yTv7YoS5O09U92YpN/0eeOnFOZP0FypjZY1XWqhLikxXlA== X-Google-Smtp-Source: AGHT+IG1OCkWK6ACc2gjb+axSi3OGauLJByZEq2XzaKVmUmtuGmaBnSVPaf+lB7MT0QcfgqXjpACp1o= X-Received: from plrc9.prod.google.com ([2002:a17:902:aa49:b0:229:2f8a:aac5]) (user=pcc job=prod-delivery.src-stubby-dispatcher) by 2002:a17:902:eb8d:b0:21f:564:80a4 with SMTP id d9443c01a7336-2292f9e5139mr16353845ad.33.1743206633220; Fri, 28 Mar 2025 17:03:53 -0700 (PDT) Date: Fri, 28 Mar 2025 17:03:37 -0700 In-Reply-To: <20250329000338.1031289-1-pcc@google.com> Precedence: bulk X-Mailing-List: linux-hardening@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20250329000338.1031289-1-pcc@google.com> X-Mailer: git-send-email 2.49.0.472.ge94155a9ec-goog Message-ID: <20250329000338.1031289-3-pcc@google.com> Subject: [PATCH v4 2/2] kasan: Add strscpy() test to trigger tag fault on arm64 From: Peter Collingbourne To: Alexander Viro , Christian Brauner , Jan Kara , Andrew Morton , Kees Cook , Andy Shevchenko , Andrey Konovalov , Catalin Marinas , Mark Rutland Cc: Vincenzo Frascino , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Will Deacon , Peter Collingbourne Content-Type: text/plain; charset="UTF-8" From: Vincenzo Frascino When we invoke strscpy() with a maximum size of N bytes, it assumes that: - It can always read N bytes from the source. - It always write N bytes (zero-padded) to the destination. On aarch64 with Memory Tagging Extension enabled if we pass an N that is bigger then the source buffer, it would previously trigger an MTE fault. Implement a KASAN KUnit test that triggers the issue with the previous implementation of read_word_at_a_time() on aarch64 with MTE enabled. Cc: Will Deacon Signed-off-by: Vincenzo Frascino Signed-off-by: Catalin Marinas Co-developed-by: Peter Collingbourne Signed-off-by: Peter Collingbourne Reviewed-by: Andrey Konovalov Link: https://linux-review.googlesource.com/id/If88e396b9e7c058c1a4b5a252274120e77b1898a --- v4: - clarify commit message - improve comment v3: - simplify test case v2: - rebased - fixed test failure mm/kasan/kasan_test_c.c | 16 ++++++++++++++++ 1 file changed, 16 insertions(+) diff --git a/mm/kasan/kasan_test_c.c b/mm/kasan/kasan_test_c.c index 59d673400085f..655356df71fe6 100644 --- a/mm/kasan/kasan_test_c.c +++ b/mm/kasan/kasan_test_c.c @@ -1570,6 +1570,7 @@ static void kasan_memcmp(struct kunit *test) static void kasan_strings(struct kunit *test) { char *ptr; + char *src; size_t size = 24; /* @@ -1581,6 +1582,21 @@ static void kasan_strings(struct kunit *test) ptr = kmalloc(size, GFP_KERNEL | __GFP_ZERO); KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr); + src = kmalloc(KASAN_GRANULE_SIZE, GFP_KERNEL | __GFP_ZERO); + strscpy(src, "f0cacc1a0000000", KASAN_GRANULE_SIZE); + + /* + * Make sure that strscpy() does not trigger KASAN if it overreads into + * poisoned memory. + * + * The expected size does not include the terminator '\0' + * so it is (KASAN_GRANULE_SIZE - 2) == + * KASAN_GRANULE_SIZE - ("initial removed character" + "\0"). + */ + KUNIT_EXPECT_EQ(test, KASAN_GRANULE_SIZE - 2, + strscpy(ptr, src + 1, KASAN_GRANULE_SIZE)); + + kfree(src); kfree(ptr); /* -- 2.49.0.472.ge94155a9ec-goog