From nobody Mon Nov 25 05:48:40 2024 Received: from mail-wm1-f48.google.com (mail-wm1-f48.google.com [209.85.128.48]) (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 E9C89199FBB; Tue, 29 Oct 2024 22:43:16 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.48 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730241799; cv=none; b=s1swfRcftJe/Yb0m9EM5TK4sdoFoCmdQ+ZoAG38JNQJ7tDQL2fTSsuL6+edhO2zbJVxiyPyp00tIrb3I+kc4eFC7Eznq85K+QtSzE/NPZU3gHotI2QSqffraRXwqVQYLLc0COy4AeSswYdmb+qEeYl7t6GZIVveuKY28ds6GgWc= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730241799; c=relaxed/simple; bh=xBy/03HYfBlb70X4LjELrQm6dmLET2cm759oyRzlIKg=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=qA1Lep6UdLsKdPTaJI4a4Go9EJoLUK4ls7/GIycKR5a1fuohjruBgk84MSoTLiL5ikQTOLXplcRWHHZleT9GS5VO5cjrvtstN2WrJu6t8d2JUd+UrTGCkCLf3/ZuwX7sBuVdvYEYYlQJoSkJNnA7Fyj3DKvTZm/ftNSfkxxXhUI= 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=MZlPtZGR; arc=none smtp.client-ip=209.85.128.48 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="MZlPtZGR" Received: by mail-wm1-f48.google.com with SMTP id 5b1f17b1804b1-4315e62afe0so60954045e9.1; Tue, 29 Oct 2024 15:43:16 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1730241795; x=1730846595; 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=NpE1d0EoW69nYU3J7zp+HGEmecn3oGwA/5+kV7hcNXc=; b=MZlPtZGR9zg3AmAQvEzFDIe6gnaMidqrBqHP34F7OHN6VOZNqcmuezsxYaGq9xEnMj S0W14RTpU7d867OLqLZ/SA6gOYmPmYDwWc83kCdcDdH4FaQRo9Th7cQG2wrbp4zhXe4L 15l1IkScD9ICT8kcIQVMY1ddbV/h1WuogoWy+62wZfK8H88Hf+scypWiOvt5EoI0i0Xz ASOrXlHIAxJf3ErYegNIfIuR2Uu3vLQlcrNo9j1tmLbfQEHoCiapwYzV1u7snJpjdJck Z8DTgX2mmdC16cMkQZzVHDLHTycbvhUelXbSRQyDPGEg29hRoYzxF+VBvUCSMvBTlyic H4kg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1730241795; x=1730846595; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=NpE1d0EoW69nYU3J7zp+HGEmecn3oGwA/5+kV7hcNXc=; b=M2xoDWRvAo0YC9hzYTjx62HgtLT5BvwdtPzhRzUT6teoLVSFWrzXodNs411JVd8+Yl 5vfATANFHH6emYXySSJUSI2NKINbbNDHzYKgNil9mQJu6wMirZPA/dfk885u/wOefc18 4LitizLg7EzDXD4E22eSIsAX5/0Py0QN+AUJlJEI+Pyy9vDSy8BOHEaHIKJ/5Jd3EUGj fVY+pTddxHPT8HbEmG+3cGKyvzecgSWm8yB1rPix7+Ga0ql4N8vvRVvh5XUqyJtPsPfk UXdh5/nY4e3U9cp5BleYOEcAw/QcpGjbyvJUFEN23pqRxqQHgDDzgYM58S6roJhK+KZs XxCw== X-Forwarded-Encrypted: i=1; AJvYcCUc0bnNNCdshTvDD3YO5eYRt/C5ikcSbGT4k32czcM9awvt3EggwmHyOsYvjwQc56d/d76SusoLTkXzE1g=@vger.kernel.org, AJvYcCXilSI8Gu1pJCPnh0HLbeyelsCZKKLzW2xgo63m0ZQwQuTl+WMaLZb8N5m0I1xhKwEOvOq7LY8o@vger.kernel.org X-Gm-Message-State: AOJu0YwcpFoSzE6+i8aPCjcrgjHD9TIjPFGy5nKGHD/mC1VgH+irJOJ9 aT48X0CkNJuQVIYYqMTRpmputgETbvfbrgSx+uUHQ27+pYAkUuUv X-Google-Smtp-Source: AGHT+IFK9fk5eMXXFOs6cc2VOy6ViQTADXNGFL9a2kyUdP69q3i86yTHcyTIUMuBDor6JBl+F+zQDA== X-Received: by 2002:a05:6000:eca:b0:37d:4a16:81d6 with SMTP id ffacd0b85a97d-38061141921mr10080745f8f.24.1730241794879; Tue, 29 Oct 2024 15:43:14 -0700 (PDT) Received: from dev7.kernelcare.com ([2a01:4f8:201:23::2]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-38058b13251sm13747192f8f.6.2024.10.29.15.43.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 29 Oct 2024 15:43:14 -0700 (PDT) From: Andrew Kanner To: mark@fasheh.com, jlbec@evilplan.org, joseph.qi@linux.alibaba.com Cc: ocfs2-devel@lists.linux.dev, linux-kernel@vger.kernel.org, Andrew Kanner , stable@vger.kernel.org, syzbot+386ce9e60fa1b18aac5b@syzkaller.appspotmail.com Subject: [PATCH] ocfs2: remove entry once instead of null-ptr-dereference in ocfs2_xa_remove() Date: Tue, 29 Oct 2024 23:43:05 +0100 Message-ID: <20241029224304.2169092-2-andrew.kanner@gmail.com> X-Mailer: git-send-email 2.43.5 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" Syzkaller is able to provoke null-ptr-dereference in ocfs2_xa_remove(): [ 57.319872] (a.out,1161,7):ocfs2_xa_remove:2028 ERROR: status =3D -12 [ 57.320420] (a.out,1161,7):ocfs2_xa_cleanup_value_truncate:1999 ERROR: P= artial truncate while removing xattr overlay.upper. Leaking 1 clusters and= removing the entry [ 57.321727] BUG: kernel NULL pointer dereference, address: 0000000000000= 004 [...] [ 57.325727] RIP: 0010:ocfs2_xa_block_wipe_namevalue+0x2a/0xc0 [...] [ 57.331328] Call Trace: [ 57.331477] [...] [ 57.333511] ? do_user_addr_fault+0x3e5/0x740 [ 57.333778] ? exc_page_fault+0x70/0x170 [ 57.334016] ? asm_exc_page_fault+0x2b/0x30 [ 57.334263] ? __pfx_ocfs2_xa_block_wipe_namevalue+0x10/0x10 [ 57.334596] ? ocfs2_xa_block_wipe_namevalue+0x2a/0xc0 [ 57.334913] ocfs2_xa_remove_entry+0x23/0xc0 [ 57.335164] ocfs2_xa_set+0x704/0xcf0 [ 57.335381] ? _raw_spin_unlock+0x1a/0x40 [ 57.335620] ? ocfs2_inode_cache_unlock+0x16/0x20 [ 57.335915] ? trace_preempt_on+0x1e/0x70 [ 57.336153] ? start_this_handle+0x16c/0x500 [ 57.336410] ? preempt_count_sub+0x50/0x80 [ 57.336656] ? _raw_read_unlock+0x20/0x40 [ 57.336906] ? start_this_handle+0x16c/0x500 [ 57.337162] ocfs2_xattr_block_set+0xa6/0x1e0 [ 57.337424] __ocfs2_xattr_set_handle+0x1fd/0x5d0 [ 57.337706] ? ocfs2_start_trans+0x13d/0x290 [ 57.337971] ocfs2_xattr_set+0xb13/0xfb0 [ 57.338207] ? dput+0x46/0x1c0 [ 57.338393] ocfs2_xattr_trusted_set+0x28/0x30 [ 57.338665] ? ocfs2_xattr_trusted_set+0x28/0x30 [ 57.338948] __vfs_removexattr+0x92/0xc0 [ 57.339182] __vfs_removexattr_locked+0xd5/0x190 [ 57.339456] ? preempt_count_sub+0x50/0x80 [ 57.339705] vfs_removexattr+0x5f/0x100 [...] Reproducer uses faultinject facility to fail ocfs2_xa_remove() -> ocfs2_xa_value_truncate() with -ENOMEM. In this case the comment mentions that we can return 0 if ocfs2_xa_cleanup_value_truncate() is going to wipe the entry anyway. But the following 'rc' check is wrong and execution flow do 'ocfs2_xa_remove_entry(loc);' twice: * 1st: in ocfs2_xa_cleanup_value_truncate(); * 2nd: returning back to ocfs2_xa_remove() instead of going to 'out'. Fix this by skipping the 2nd removal of the same entry and making syzkaller repro happy. Cc: stable@vger.kernel.org Fixes: 399ff3a748cf ("ocfs2: Handle errors while setting external xattr val= ues.") Reported-by: syzbot+386ce9e60fa1b18aac5b@syzkaller.appspotmail.com Closes: https://lore.kernel.org/all/671e13ab.050a0220.2b8c0f.01d0.GAE@googl= e.com/T/ Tested-by: syzbot+386ce9e60fa1b18aac5b@syzkaller.appspotmail.com Signed-off-by: Andrew Kanner --- fs/ocfs2/xattr.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/ocfs2/xattr.c b/fs/ocfs2/xattr.c index dd0a05365e79..5bc4d660e15a 100644 --- a/fs/ocfs2/xattr.c +++ b/fs/ocfs2/xattr.c @@ -2036,7 +2036,7 @@ static int ocfs2_xa_remove(struct ocfs2_xa_loc *loc, rc =3D 0; ocfs2_xa_cleanup_value_truncate(loc, "removing", orig_clusters); - if (rc) + if (rc =3D=3D 0) goto out; } } --=20 2.43.5