From nobody Tue Dec 2 01:51:17 2025 Received: from mail-pl1-f195.google.com (mail-pl1-f195.google.com [209.85.214.195]) (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 E6E0D363C6F for ; Thu, 20 Nov 2025 17:17:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.195 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763659075; cv=none; b=HNzgkbOqf61mdE6Y1TxaWdAHMPLmvD7plDAhR6jydoY77xweH3mppMPUvF7CiYmTnU4EUhku+mYp6/liLGpZFz94G15WqZEm79v4kKj738a9S/KnbO46/iwgNTUuMASIXUnqwdrkHsLGP6xwUqLGomZ4xtuj5ilTpb+OtSogvjQ= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763659075; c=relaxed/simple; bh=p3ApoAA1CanQQdozSlHOXOSokHr0N8H00lCqp1aC2iI=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=cfrdCzZHzyi3k/VXxtJKW/4THDHGDiR0OH9rX1Ow5du6dl4RFTP8v4oHN5qXsnEXxmQyJ2U6M0tTTILofTjj98pubTpd5qnkVweTXxht6aNIBDE/nHvo6RRgT48GIrOiaApi6RfabUNIaDKHwlmCNi4X86zgMhiA8M1QUPIM4kI= 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=209.85.214.195 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-f195.google.com with SMTP id d9443c01a7336-2981f9ce15cso13062435ad.1 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=fEXP7Cjs8rDP/Wix/03CniofH/mkpdbBidnQveZ+nXb6QcrSx5Qr78bUZRYZ9zyyKx oLUfEEPC8Wo7yNSLg8eimTVQf9ITBxoHvvC8fSxVy19OjSumM9syH3aGLep7g0+d4Ra5 QhCaVmmKXkJCrFKLIcshVmOe8uv7+VeS03my2R9pL7zicbYFXZ13qq1dZR7IPQ/2/GyH vINKlkk3l3wzRIv5p26MMKhfCHB8zTD4L9uc7vXoM3NRn9kNtpweIcmuFiWRAarpCHAh CG4/LxonJ4MuuAZEKYJFbuiZvSyGzALX57dWm3FcDpKouzZuU0Oey3vfgKUblYBieMna WEHA== X-Forwarded-Encrypted: i=1; AJvYcCV6asxx3mpW60CecWWZAsC6KLS1TQ2A8i5yYYwi2gHjbOm8+7fKRhLj5S/M1cyJvTaGXKQsYZ8QEqcICx0=@vger.kernel.org X-Gm-Message-State: AOJu0YyWtONFQKV0uLO6GEuYWPskaqGXDv126LpyYh///DqvCgUXY1Wb ONwccCr8s+cX7/LSLJoRakmHCZCg61GAlv5+shuxu6EaLrosS8p1hbeub65bsEt8gM0= X-Gm-Gg: ASbGncspd6CnQ9rTPf9iJNh4Iek9r6QeE25MSnwLdRpgPpxUGLxERmjHD5KPcbf5vN/ dtR4eduG6vomoLLdVbdHFDjNr1sgEenwMSS87tE1lveHVl0+2MYAgRFvPCcdJACG8YJNtAXDNVv h+uU4OOTbXMqTyN1/rIGqiWqDITVYRL7asu+GsMQ7wxaK+mgNRPnU4C1XGtzKPd//49dLo89Rt7 FaWMMOcQM2elXn6Ge/ziOFStyH6hZx3ObOnI/SkW2JQxX1rSA7tCPL6lgE3AKvQ+jhz3fq2f8EN CctJayLx+pkXBBpjJaqTUNjUiOqypYPzWL3OR3LlYPgn4E/xWKMGBP4XLzclcRhw7yUu03snqPK LV1wqCfD9I5fICqKy19N2GaqON2ZgOeJ9IVk6GZPxX8YvJX7/g9JScwZna6TXw37eHZpY+Cu4Kd jWYOgWVrFijktCGFEhO2WQwGPJ0p0zRwGVv0c9AxzCadt8TgfXYmASUcVN 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-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" 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 =3D 432 bytes uninitialized For files: 520 - 248 =3D 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=3D905d785c4923bea2c1db 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; =20 folder =3D &entry->folder; - memset(folder, 0, sizeof(*folder)); + /* Zero the entire union to avoid leaking uninitialized data */ + memset(entry, 0, sizeof(*entry)); folder->type =3D cpu_to_be16(HFSPLUS_FOLDER); if (test_bit(HFSPLUS_SB_HFSX, &sbi->flags)) folder->flags |=3D 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; =20 file =3D &entry->file; - memset(file, 0, sizeof(*file)); + /* Zero the entire union to avoid leaking uninitialized data */ + memset(entry, 0, sizeof(*entry)); file->type =3D cpu_to_be16(HFSPLUS_FILE); file->flags =3D cpu_to_be16(HFSPLUS_FILE_THREAD_EXISTS); file->id =3D cpu_to_be32(cnid); --=20 2.34.1