From nobody Tue Dec 16 23:58:43 2025 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 759902C11CE for ; Wed, 10 Dec 2025 22:46:43 +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=1765406803; cv=none; b=IxQ0o+kar6mmVpOxcvFkuWyEwYet9WDgOo1EofAykOhcXDFjBcNlRtRw28kjCKYUcZeTVR7mXSsg4134Kv3RsffKM5eJewLgtVuMPaymrNpappGuvGU/O9+AHXdWq5eBdyuo0fid5uWJXhR2pvk4egNhDo55NrVGJAWdM7/cfgA= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765406803; c=relaxed/simple; bh=Rsfmd7zbC+kSZ3iat7Z+yufKodHJKLHaalHhwgTU+L8=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=IeOw/W6hqMsqr3s9O32HvFFfhUTAWtxQR+27p61U6g0GfzpvRUBofhxJsv6eiBsl88mwXVvJ0CBwahSNUzb9Oq8gnzpLwxml0eBIdfIOiZtK2fpstZp/EBvqRzctP6Ci29Vgs58gJt+K+saepBScJ2H6EQ/sZlaq2dRvoEAPogo= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=GgfixRCi; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="GgfixRCi" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 617C3C4CEF7; Wed, 10 Dec 2025 22:46:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1765406803; bh=Rsfmd7zbC+kSZ3iat7Z+yufKodHJKLHaalHhwgTU+L8=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=GgfixRCi7D7zmf3LonNP4Ozluj3wnGSed4vLDV4g17ge/6u5M1FsXvVGvX9p4ZrpS M+IsDN9v6aU9atxImKnxkehgn/1UxkHVP0Mn0N9ScQY/Qv0ZJnH2hOmqw9hL/KZ8lI kOheLRRqM/O3o7/HcKvk8lLIhulQdS3hWsRx9Y7iJ9gwrdwXI8VFVf0fXYo4lvIpyR nCc4DBMJDwv6nwS7OZhwHtWVz81y/SAHIp9VrpBNaXQoG6UehgOSeq6bPOHLxmXgJ4 RWiF73VfH7N+ezRbnYv5wey494xpQZoY09iLJkLrZCoBznINB1eJgpdCwVroGuGduU d7cpqDth50dig== Date: Wed, 10 Dec 2025 23:46:38 +0100 From: Alejandro Colomar To: linux-kernel@vger.kernel.org, linux-mm@kvack.org Cc: Alejandro Colomar , Kees Cook , Christopher Bazley , Rasmus Villemoes , Marco Elver , Michal Hocko , Linus Torvalds , Al Viro , Alexander Potapenko , Dmitry Vyukov , Jann Horn , Andrew Morton , "Maciej W. Rozycki" Subject: [PATCH v5 2/4] mm: Fix benign off-by-one bugs Message-ID: <9c38dd009c17b0219889c7089d9bdde5aaf28a8e.1765406337.git.alx@kernel.org> X-Mailer: git-send-email 2.51.0 References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" We were wasting a byte due to an off-by-one bug. s[c]nprintf() doesn't write more than $2 bytes including the null byte, so trying to pass 'size-1' there is wasting one byte. Acked-by: Marco Elver Cc: Kees Cook Cc: Christopher Bazley Cc: Alexander Potapenko Cc: Dmitry Vyukov Cc: Alexander Potapenko Cc: Jann Horn Cc: Andrew Morton Cc: Linus Torvalds Cc: Rasmus Villemoes Cc: Marco Elver Cc: Michal Hocko Cc: Al Viro Signed-off-by: Alejandro Colomar Message-ID: <515445ae064d4b8599899bf0d8b480dadd2ff843.1752182685.git.alx@ke= rnel.org> --- mm/kfence/kfence_test.c | 4 ++-- mm/kmsan/kmsan_test.c | 2 +- 2 files changed, 3 insertions(+), 3 deletions(-) diff --git a/mm/kfence/kfence_test.c b/mm/kfence/kfence_test.c index 00034e37bc9f..5725a367246d 100644 --- a/mm/kfence/kfence_test.c +++ b/mm/kfence/kfence_test.c @@ -110,7 +110,7 @@ static bool report_matches(const struct expect_report *= r) =20 /* Title */ cur =3D expect[0]; - end =3D &expect[0][sizeof(expect[0]) - 1]; + end =3D ARRAY_END(expect[0]); switch (r->type) { case KFENCE_ERROR_OOB: cur +=3D scnprintf(cur, end - cur, "BUG: KFENCE: out-of-bounds %s", @@ -140,7 +140,7 @@ static bool report_matches(const struct expect_report *= r) =20 /* Access information */ cur =3D expect[1]; - end =3D &expect[1][sizeof(expect[1]) - 1]; + end =3D ARRAY_END(expect[1]); =20 switch (r->type) { case KFENCE_ERROR_OOB: diff --git a/mm/kmsan/kmsan_test.c b/mm/kmsan/kmsan_test.c index 902ec48b1e3e..b5ad5dfb2c00 100644 --- a/mm/kmsan/kmsan_test.c +++ b/mm/kmsan/kmsan_test.c @@ -105,7 +105,7 @@ static bool report_matches(const struct expect_report *= r) =20 /* Title */ cur =3D expected_header; - end =3D &expected_header[sizeof(expected_header) - 1]; + end =3D ARRAY_END(expected_header); =20 cur +=3D scnprintf(cur, end - cur, "BUG: KMSAN: %s", r->error_type); =20 --=20 2.51.0