From nobody Sat Feb 7 08:02:09 2026 Received: from mail-pg1-f194.google.com (mail-pg1-f194.google.com [209.85.215.194]) (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 A0C2D2848A8 for ; Tue, 27 Jan 2026 07:54:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.215.194 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769500464; cv=none; b=dVeuRIVamDmEbwFwD7kzjL8p7DI3b7BhAzD8/vJaTlhlE9HnKeyisvjj4ettUntITA0HYI9N63rB+tle3fbiE8sQ/yQzSedXINZBW3zfOOJdxN2lSJ/NQTYDmETHKYgzY27rjzHCat085WrOX3YrO3az7WranfHumOr7VGPJnPI= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769500464; c=relaxed/simple; bh=sva4oJ/jLabX24xc2S6XLTPNwMIB2gnGJhMFmbQdvy8=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=H0QGcFZ5cAHXrapIDX85orkVWb4rbIV86XpPLc0vWAFj9OX/DOpjXhs0chI7c+0pHa6ucMFdqS68PUpNdNxWZJxuPnU2VHq19hft0eswLqMaJxUjUaWluc7O0pGJxpB2r9XAxXmUvyOE2eZjwiboG3JlJd0MFrKYDYJK5a94dfA= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=NPJJVw82; arc=none smtp.client-ip=209.85.215.194 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="NPJJVw82" Received: by mail-pg1-f194.google.com with SMTP id 41be03b00d2f7-c56188aef06so2184636a12.2 for ; Mon, 26 Jan 2026 23:54:23 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1769500463; x=1770105263; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=DxtHOOpBiQrOJRLwsbdkcCVvw91TG/jEwLuMVFsF7UQ=; b=NPJJVw82MB3lWOzmFGv9xleLIfb1TwH9nAmcQWVzXDhu0a5evXtALhLGnW+gL0DNqQ lW+umzdQ5shTQfttcxmJWaxYvNhAdCX5lNAIFwgksGQnH77e+fkiri4MQovRuPlUQdGP BYAhjNiJu9IYM0AQTCTC8GvPQEzIHO5u0Sn2hi4VMFsQLhQTkPcSqcMIX83QAeb5rD8t WG8twGpfGVm+eDbeut34QUn9hVrISgZqB1jDrO3heqM/e27bwtI8iCvXWCo79NgOdZcJ gAydfreJORy22XCQBYf68/gnhcJgrZmT57yk1DnGNsTUsinkQ39DnFsjfWxIUZ9OaloB l5Zw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1769500463; x=1770105263; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-gg:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=DxtHOOpBiQrOJRLwsbdkcCVvw91TG/jEwLuMVFsF7UQ=; b=bHyWZW7DSfXtRMKgIpZT+FWn+E01v8ZI9zrCQ+yi0tG/P8KT+jXzVPDzoTaanKm1q+ gaDrk7VVme2X9VYdG0KkdsuGFwvKYwtEqL8+xLVEJhvZMfCBU+BkzXbt5xTm3JcC1Uj9 YZjWN8PZRAFqQk6pCVonjg8WfZc2XZcX6ugLYWuK2bRWUBX4hOmsMVYLJo97NRZYsHIl IuKc+UxfPzzUI9VkGZRNcF2Z8AcwqyaGZNh6dYTzJxf+62eK5G+B89nC3l/OY7XTEgZ/ bxaFj13m8s5onKP1EtxQuUi4tP7jN4e1qKin1OVkKjLnc44YA+/0x1ZMviO/fslTltxp QUSA== X-Forwarded-Encrypted: i=1; AJvYcCUpYvWHgyENZA529KUM6vRCVbPechN2t9lq9pIiXgBYXKf4ncyifUn6FtRRKunb0yXt6uVUCLOVHM3zVh0=@vger.kernel.org X-Gm-Message-State: AOJu0Yw8IuS17wG8ykt3SABut5FcnUJeBwxBvGr6pfaFNGhZ3MFbkcuV 7yRxXnHzfj8PAQl2BZsETFRscLyNsAT7wfKa92+dgRWtpStEv3q0LI5i9Yrxp5+S X-Gm-Gg: AZuq6aIugXvgBV2818F5iRck6Dh84CpNTwV21/elFpbg7qgbZo6cZNLUDcqQY5JaYDw DyXkqMc3Ye8J6YYEScT+y65Os0dTIjlndvT1B77EzxfhmVXyAWSd5gvyo0yGkLwIUUmC2RJBBlO rpZDyM+oRp2Oe6RpMzcJ6Y3bgxy/IHjE2qJmop8HCKMiCUCiqZCTY9cmwYh8xD9Hxlvd2D1asff ofLHR9U4wICSN541snRzclhUAA1aKMlxQYTGFSzg48jK8S+Ez+ZC01ldkjbd+nYTadEAY0nHr/K QQ/4d+2ryTaELtcbLKhDpvqMcTAqvscH+R39VNAS5+zolViGPg7CgPOTKyH/DedVqV7MGI99jnT z/NCkIPfbQP4sZZCgcMGxSrQjovYKkYhS0ovkCZN76xV5CDRuxrVj06knAzbE1fiEo6gXLpSAiq QVBMWqT8UpP/DyORloTkLbjEix28kSPOdIfKkifg== X-Received: by 2002:a17:90a:d404:b0:343:b610:901c with SMTP id 98e67ed59e1d1-353fed87a55mr1008063a91.26.1769500462899; Mon, 26 Jan 2026 23:54:22 -0800 (PST) Received: from lima-ubuntu.hz.ali.com ([47.246.98.220]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-3536aeeec03sm4575762a91.0.2026.01.26.23.54.19 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 26 Jan 2026 23:54:22 -0800 (PST) From: Qing Wang To: Miklos Szeredi , Amir Goldstein Cc: linux-unionfs@vger.kernel.org, linux-kernel@vger.kernel.org, Qing Wang , syzbot+d130f98b2c265fae5297@syzkaller.appspotmail.com Subject: [PATCH] ovl: Fix uninit-value in ovl_fill_real Date: Tue, 27 Jan 2026 15:54:04 +0800 Message-Id: <20260127075404.1110552-1-wangqing7171@gmail.com> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Syzbot reported a KMSAN uninit-value issue in ovl_fill_real. This iusse's call chain is: __do_sys_getdents64() -> iterate_dir() ... -> ext4_readdir() -> fscrypt_fname_alloc_buffer() // alloc -> fscrypt_fname_disk_to_usr // write without tail '\0' -> dir_emit() -> ovl_fill_real() // read by strcmp() The string is used to store the decrypted directory entry name for an encrypted inode. As shown in the call chain, fscrypt_fname_disk_to_usr() write it wthout null-terminate. However, ovl_fill_real() uses strcmp() to compare the name against "..", which assumes a null-terminated string and may trigger a KMSAN uninit-value warning when the buffer tail contains uninit data. Reported-by: syzbot+d130f98b2c265fae5297@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=3Dd130f98b2c265fae5297 Fixes: 4edb83bb1041 ("ovl: constant d_ino for non-merge dirs") Signed-off-by: Qing Wang --- fs/overlayfs/readdir.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/overlayfs/readdir.c b/fs/overlayfs/readdir.c index 160960bb0ad0..2581cb33fb87 100644 --- a/fs/overlayfs/readdir.c +++ b/fs/overlayfs/readdir.c @@ -755,7 +755,7 @@ static bool ovl_fill_real(struct dir_context *ctx, cons= t char *name, struct dir_context *orig_ctx =3D rdt->orig_ctx; bool res; =20 - if (rdt->parent_ino && strcmp(name, "..") =3D=3D 0) { + if (rdt->parent_ino && strncmp(name, "..", 2) =3D=3D 0) { ino =3D rdt->parent_ino; } else if (rdt->cache) { struct ovl_cache_entry *p; --=20 2.34.1