From nobody Fri Apr 17 00:17:59 2026 Received: from mail-wm1-f74.google.com (mail-wm1-f74.google.com [209.85.128.74]) (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 F1FC13A9605 for ; Tue, 24 Feb 2026 17:04:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.74 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771952671; cv=none; b=cXjntJaQ0Q2EPQQGqP1j1hf0+CrMIOYc5wM3aCBRPI/clbcCLf4d9okofeCgWiPszpsF3HGZ7rFGuHjssaH5YDNq+RxJJbmQutp1S4xXTQyxeFJAIvVLFufd1XXDZ23vtD10VNBInwwzm18kRW6b/3dvrehMoR8v/Ah0mWV6fJc= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1771952671; c=relaxed/simple; bh=kyJx0abKsM+ye4/sGjKOKOe8QO0KJKvhi9JvpmTKgFE=; h=Date:Mime-Version:Message-ID:Subject:From:To:Cc:Content-Type; b=YGwnV2XKl42qm6ZqIGIFXoELWe1i0/jUQpQvhWxpGu9TA/6Y70gyQbQlDScCyRquZoCwhQ/8n/ds59io+BQ4NkF6beWCbXxtpPwAoOtd5mKA8ZPaNzzMq0J8gWNrMjjrLr8lpIC/3/aX5xXvwsgblkAn0KvPAl/jz4y5o9MYZKc= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--tabba.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=NKdx6fRv; arc=none smtp.client-ip=209.85.128.74 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--tabba.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="NKdx6fRv" Received: by mail-wm1-f74.google.com with SMTP id 5b1f17b1804b1-4836cc0b38eso12221385e9.2 for ; Tue, 24 Feb 2026 09:04:29 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1771952668; x=1772557468; darn=vger.kernel.org; h=cc:to:from:subject:message-id:mime-version:date:from:to:cc:subject :date:message-id:reply-to; bh=wEqFN9UUEKzcXYtb/M8n+iE3sou79Y04zVjpTLary3Y=; b=NKdx6fRvqciccoMzqn+K0vxJ8d437vwlykUyCFHYSSmFX55IU3G419J0nDtDZvGEJZ 2JSiHHSl/kojyomM9sDDHoxeeD4N3WyXdbPu2shuSdOqy3zR4v+VGGVdrJBP0BZACm7M I4pNQFWiailpaU5DfVfT4EiWY4VjIKCFT0MRKUOVMBTzCIpjf4HHAP+bwfJDh12XT69k lzkZOdP7b353Isp8vqUnrKgJRcXxde8sW9k1CnesD8GX2YfUTseLXoxbYn9gM41kVtTn D0Cqoq0Bu04jG+e8N6KJqhlceOuEFGEaaFDBfwW0oFq1BJkHGLyZPzfUV3nVYRYaSfBJ woMw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1771952668; x=1772557468; h=cc:to:from:subject:message-id:mime-version:date:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=wEqFN9UUEKzcXYtb/M8n+iE3sou79Y04zVjpTLary3Y=; b=m/7FPu6JWuHTzgupaHV+Bv/18QML7rNkuqhWJ7zE/QI4j66xcrWBe6QXC97tDTqjRu yGOd71+s89R/mRrv7xJ694tXCrSDbzJqKrbLh6Q/GutZKhxDuunGOUSy0YsZWtpFjCXB BGcsvoW0lKhB0WTs8v8BYT3vOb8t4lD7VSbk2KRGCSoTmGtLn1HQn2F1q/SZ+HM+V0vl thFaqjE6zb4traMC8mtDU5JZ3zC/Vokls2fSktANLW+dZsne0dFGn6ZzbI2vxEmrC7X4 kXx6QCzCMIP9VrVYhkgk6GiAia2LNc/HAJh7sazxSlPtZ2Fud5kPDQ0Nq90k7v5/xwi3 UEQA== X-Forwarded-Encrypted: i=1; AJvYcCUc74diTipeHl47vyk909jswm781cGYjlf4ACmsvfu8OEIaQhHpECehKCd1X4zH3+mVEabymnyAMPP/ol0=@vger.kernel.org X-Gm-Message-State: AOJu0YzH4mxMNlbs+o3qPsHqGwYMusAbQo5D8jmGY1y94hSMVmLSuHaV k+dUZTbJhqB4NlG8BTagFgZ4mKo5Y/rOa+s6Jxa1r5x8zzAa0YKfq5UwHv2QBL4yVEGj/hBlQ7n 8mg== X-Received: from wrbck7.prod.google.com ([2002:a5d:5e87:0:b0:439:8c91:524d]) (user=tabba job=prod-delivery.src-stubby-dispatcher) by 2002:a05:600c:5394:b0:483:6a8d:b2fc with SMTP id 5b1f17b1804b1-483a95b7162mr185229535e9.8.1771952668202; Tue, 24 Feb 2026 09:04:28 -0800 (PST) Date: Tue, 24 Feb 2026 17:04:27 +0000 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 X-Mailer: git-send-email 2.53.0.371.g1d285c8824-goog Message-ID: <20260224170427.2296592-1-tabba@google.com> Subject: [PATCH] lib/string: Fix UBSAN misaligned access in sized_strscpy From: Fuad Tabba To: Kees Cook , Andy Shevchenko , Andrew Morton Cc: linux-hardening@vger.kernel.org, linux-kernel@vger.kernel.org, will@kernel.org, tabba@google.com Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" sized_strscpy() performs word-at-a-time writes to the destination buffer. If the destination buffer is not aligned to unsigned long, direct assignment causes UBSAN misaligned-access errors. Use put_unaligned() to safely write the words to the destination. Fixes: 30035e45753b7 ("string: provide strscpy()") Signed-off-by: Fuad Tabba --- lib/string.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/lib/string.c b/lib/string.c index b632c71df1a5..a1697bf72078 100644 --- a/lib/string.c +++ b/lib/string.c @@ -157,16 +157,16 @@ ssize_t sized_strscpy(char *dest, const char *src, si= ze_t count) if (has_zero(c, &data, &constants)) { data =3D prep_zero_mask(c, data, &constants); data =3D create_zero_mask(data); - *(unsigned long *)(dest+res) =3D c & zero_bytemask(data); + put_unaligned(c & zero_bytemask(data), (unsigned long *)(dest+res)); return res + find_zero(data); } count -=3D sizeof(unsigned long); if (unlikely(!count)) { c &=3D ALLBUTLAST_BYTE_MASK; - *(unsigned long *)(dest+res) =3D c; + put_unaligned(c, (unsigned long *)(dest+res)); return -E2BIG; } - *(unsigned long *)(dest+res) =3D c; + put_unaligned(c, (unsigned long *)(dest+res)); res +=3D sizeof(unsigned long); max -=3D sizeof(unsigned long); } --=20 2.53.0.371.g1d285c8824-goog