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From: Dan Carpenter <dan.carpenter@oracle.com>
To: Peilin Ye <yepeilin.cs@gmail.com>
Cc: linux-fsdevel@vger.kernel.org, syzkaller-bugs@googlegroups.com,
	linux-kernel-mentees@lists.linuxfoundation.org,
	linux-kernel@vger.kernel.org
Subject: Re: [Linux-kernel-mentees] [PATCH] hfs, hfsplus: Fix NULL pointer dereference in hfs_find_init()
Date: Wed, 12 Aug 2020 11:59:04 +0300	[thread overview]
Message-ID: <20200812085904.GA16441@kadam> (raw)
In-Reply-To: <20200812071306.GA869606@PWN>

Yeah, the patch doesn't work at all.  I looked at one call tree and it
is:

hfs_mdb_get() tries to allocate HFS_SB(sb)->ext_tree.

	HFS_SB(sb)->ext_tree = hfs_btree_open(sb, HFS_EXT_CNID, hfs_ext_keycmp);
                    ^^^^^^^^

hfs_btree_open() calls page = read_mapping_page(mapping, 0, NULL);
read_mapping_page() calls mapping->a_ops->readpage() which leads to
hfs_readpage() which leads to hfs_ext_read_extent() which calls
res = hfs_find_init(HFS_SB(inode->i_sb)->ext_tree, &fd);
                                         ^^^^^^^^

So we need ->ext_tree to be non-NULL before we can set ->ext_tree to be
non-NULL...  :/

I wonder how long this has been broken and if we should just delete the
AFS file system.

regards,
dan carpenter

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  parent reply	other threads:[~2020-08-12  8:59 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-12  6:55 [Linux-kernel-mentees] [PATCH] hfs, hfsplus: Fix NULL pointer dereference in hfs_find_init() Peilin Ye
2020-08-12  7:08 ` Greg Kroah-Hartman
2020-08-12  7:13   ` Peilin Ye
2020-08-12  8:18     ` Greg Kroah-Hartman
2020-08-12 16:33       ` Peilin Ye
2020-08-12  8:59     ` Dan Carpenter [this message]
2020-08-12 11:42       ` Big Budsupply
2020-08-12 17:23       ` Peilin Ye
2020-08-12 20:24       ` Ernesto A. Fernández
2020-08-12 20:34         ` Ernesto A. Fernández

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