Wang Jianjian d0aa72604f quota: Fix potential NULL pointer dereference
Below race may cause NULL pointer dereference

P1					P2
dquot_free_inode			quota_off
					  drop_dquot_ref
					   remove_dquot_ref
					   dquots = i_dquot(inode)
  dquots = i_dquot(inode)
  srcu_read_lock
  dquots[cnt]) != NULL (1)
					     dquots[type] = NULL (2)
  spin_lock(&dquots[cnt]->dq_dqb_lock) (3)
   ....

If dquot_free_inode(or other routines) checks inode's quota pointers (1)
before quota_off sets it to NULL(2) and use it (3) after that, NULL pointer
dereference will be triggered.

So let's fix it by using a temporary pointer to avoid this issue.

Signed-off-by: Wang Jianjian <wangjianjian3@huawei.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Message-Id: <20240202081852.2514092-1-wangjianjian3@huawei.com>
2024-02-05 15:57:34 +01:00
2023-12-20 19:26:31 -05:00
2024-01-21 14:11:32 -08:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.
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