From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pl1-f196.google.com (mail-pl1-f196.google.com [209.85.214.196]) (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 E0DDE2BF000 for ; Thu, 20 Nov 2025 17:17:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.196 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763659076; cv=none; b=eEsKqkJk8byEz53psOc0t08aJrDlEKrUIehmvA4Ms6NenVzwjJuFk+oZwaEmzjWM6FP8TQeZFfq2YXPJUqisOf3jlUIaHTgAY02T2hHXdlAOqxRqE6ycwC2Q+idiBWPldcweHk+hb3ypG6pAXL2YmW4Ev5Kk+lZwUJOtU3KelCE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763659076; c=relaxed/simple; bh=p3ApoAA1CanQQdozSlHOXOSokHr0N8H00lCqp1aC2iI=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=plBa2SZLMlGYhHEqtvGl8K1J4GvzGfeAUoKWkvmyUKHKNjH1+YP0rHhP/ri3WqSoVRsR69mjdh3qNqnUL0m8nEU+hsUuRBmKLKD+RZx7HAzWnqbPtBFwaGhakSi1IL7uN5O62CZ/y3xZd5TzeLqXhQV7I7nObCN4LHbfb4Dd+nQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=ee.vjti.ac.in; spf=none smtp.mailfrom=ee.vjti.ac.in; dkim=pass (1024-bit key) header.d=vjti.ac.in header.i=@vjti.ac.in header.b=MlnmexGa; arc=none smtp.client-ip=209.85.214.196 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=ee.vjti.ac.in Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=ee.vjti.ac.in Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=vjti.ac.in header.i=@vjti.ac.in header.b="MlnmexGa" Received: by mail-pl1-f196.google.com with SMTP id d9443c01a7336-29558061c68so15255695ad.0 for ; Thu, 20 Nov 2025 09:17:52 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=vjti.ac.in; s=google; t=1763659072; x=1764263872; 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=lxUmT50gh4iATr6XFekF1hQSSR5/JtG5gjuDPPL7SIo=; b=MlnmexGaMVr3imvxoJ4QGKECxdM+vAXKLmRiJQYIzLsJI671TUmLGe07p5Xu6rdLAz VBeJy/Hg8xz3XJgTc3/utqERb3/wcWZ0COG0LJ2kecUHYWOWt3t805xW5OLMi32bU33C vogr2jZfdEnJ0FTH/WEnYjSI2LU9+nwh0XLT0= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1763659072; x=1764263872; 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=lxUmT50gh4iATr6XFekF1hQSSR5/JtG5gjuDPPL7SIo=; b=btoWx8dY27jY3LwTbgXdeSzhGlGoI6BJSt35CgeSrhEfVdokY3PVmlzWKGkkubLQ/j SwFfd7yIC3f+1rx7Xmajkc+Kas0lXzaDH6d1bFUYDBW7SaD7C0vh7Zdee7eofylKujkO 5ORQPdPDlyGWNDv8LaK5jDWzcx5iRH9UetHu3ryITpTIkOd7HNJhQkkZvOS+2o2e54qm 4qAk3PFmjSL/8FS5zeDxwtfOJui5fudvImA4hEAXprX4gSHTg7nGDGlX+YLqBIbLjPTy wJUkSgBvmGHn8SzhG/uGdUAvDzjBz/vpYcYyeboUbAlzWfi5mP6qRF/sWXPUOaXWquO9 gj3A== X-Forwarded-Encrypted: i=1; AJvYcCWaUM6CgUj21rgm+kIpXE2Ty33vMWRfrdctFBZ0e937fEWKiFtA/GGPhEHAtvRexnz2q9+U3Q6/+Zc9uyap@vger.kernel.org X-Gm-Message-State: AOJu0Yzil3On+mXyhKiGqjREuIrXcGjCYEYy8sdhaMuSDkoV6wb2ITkQ kUqDy7m5bqHhkZzYQJIbcReMYaI4WJx/ihHbjt7gDlGnC7r28F0V77JlByCqBQiGQnA= X-Gm-Gg: ASbGncswUcAxwrM0AnGrjpuy+3HtyZOiyWEe3cPtrzASSYRlElD7mjrFwtDdrY2EA37 j4W8kKUPc/Q7tVVOPwZT3DPiFCSli0KdsjBlknXd6u/YnA1STU4wITxc9G/Bb2ZuwscgNUhr9yr u/FcwAZvbwWfttlktuEUKU1CnyBtjdhWX12wcAZjp1UxfjN2PVGg7dcKVYqtPymu5wY8234oN2+ mgXQH37N5EBboS8wtWAUvZ8VU3VrZk8fhJeoWz0lyQzZ3+S2vNKpvpOmBn67xg88AA3tMlYTPBQ e11CaykJnLHPF8A//Q8rTum9402qrVZEkSdbCIr4Hv8D/6s2iMxYrxkNwWWUyehgcphONjlqP3Y hDjdXX8KjyY+ja/THRnTQbMx+iNdN0quQmlmQg3bsoFCamLGUIWMUMW7h1MpvgXPhWLCRVkyvL8 wZqwOqYy0V2PZlZu9DUAku5sgDzTQ1QIUtiqWdTU4P4d/HzOPRaEf3/N0M X-Google-Smtp-Source: AGHT+IHCvcH3jSOL7T+a7yDjy7MxfxbirT83K6TJhLThLkL3l4+krsnqHTMe0gk5zEdG6sGJ5ZT/Vg== X-Received: by 2002:a17:902:f791:b0:298:3545:81e2 with SMTP id d9443c01a7336-29b5ebbf688mr43341815ad.22.1763659072115; Thu, 20 Nov 2025 09:17:52 -0800 (PST) Received: from ranegod-HP-ENVY-x360-Convertible-13-bd0xxx.. ([2405:201:31:d869:1daf:dd82:99d2:95eb]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-29b5b2700ddsm32223085ad.70.2025.11.20.09.17.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 20 Nov 2025 09:17:51 -0800 (PST) From: ssrane_b23@ee.vjti.ac.in X-Google-Original-From: ssranevjti@gmail.com To: slava@dubeyko.com, glaubitz@physik.fu-berlin.de, frank.li@vivo.com, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Cc: skhan@linuxfoundation.org, linux-kernel-mentees@lists.linux.dev, david.hunter.linux@gmail.com, khalid@kernel.org, Shaurya Rane , syzbot+905d785c4923bea2c1db@syzkaller.appspotmail.com Subject: [PATCH] hfsplus: fix uninit-value in hfsplus_cat_build_record Date: Thu, 20 Nov 2025 22:47:40 +0530 Message-Id: <20251120171740.19537-1-ssranevjti@gmail.com> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Shaurya Rane The root cause is in hfsplus_cat_build_record(), which builds catalog entries using the union hfsplus_cat_entry. This union contains three members with significantly different sizes: struct hfsplus_cat_folder folder; (88 bytes) struct hfsplus_cat_file file; (248 bytes) struct hfsplus_cat_thread thread; (520 bytes) The function was only zeroing the specific member being used (folder or file), not the entire union. This left significant uninitialized data: For folders: 520 - 88 = 432 bytes uninitialized For files: 520 - 248 = 272 bytes uninitialized This uninitialized data was then written to disk via hfs_brec_insert(), read back through the loop device, and eventually copied to userspace via filemap_read(), resulting in a leak of kernel stack memory. Fix this by zeroing the entire union before initializing the specific member. This ensures no uninitialized bytes remain. Reported-by: syzbot+905d785c4923bea2c1db@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=905d785c4923bea2c1db Fixes: 1da177e4c3f4 Signed-off-by: Shaurya Rane --- fs/hfsplus/catalog.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/fs/hfsplus/catalog.c b/fs/hfsplus/catalog.c index 02c1eee4a4b8..4d42e7139f3b 100644 --- a/fs/hfsplus/catalog.c +++ b/fs/hfsplus/catalog.c @@ -111,7 +111,8 @@ static int hfsplus_cat_build_record(hfsplus_cat_entry *entry, struct hfsplus_cat_folder *folder; folder = &entry->folder; - memset(folder, 0, sizeof(*folder)); + /* Zero the entire union to avoid leaking uninitialized data */ + memset(entry, 0, sizeof(*entry)); folder->type = cpu_to_be16(HFSPLUS_FOLDER); if (test_bit(HFSPLUS_SB_HFSX, &sbi->flags)) folder->flags |= cpu_to_be16(HFSPLUS_HAS_FOLDER_COUNT); @@ -130,7 +131,8 @@ static int hfsplus_cat_build_record(hfsplus_cat_entry *entry, struct hfsplus_cat_file *file; file = &entry->file; - memset(file, 0, sizeof(*file)); + /* Zero the entire union to avoid leaking uninitialized data */ + memset(entry, 0, sizeof(*entry)); file->type = cpu_to_be16(HFSPLUS_FILE); file->flags = cpu_to_be16(HFSPLUS_FILE_THREAD_EXISTS); file->id = cpu_to_be32(cnid); -- 2.34.1