From: Al Viro <viro@zeniv.linux.org.uk>
To: sunliming@linux.dev
Cc: miklos@szeredi.hu, amir73il@gmail.com,
linux-unionfs@vger.kernel.org, linux-kernel@vger.kernel.org,
sunliming <sunliming@kylinos.cn>
Subject: Re: [PATCH] ovl: Fix possible NULL pointer dereference in ovl_destroy_inode
Date: Wed, 22 Apr 2026 05:10:32 +0100 [thread overview]
Message-ID: <20260422041032.GH3518998@ZenIV> (raw)
In-Reply-To: <20260421092349.148002-1-sunliming@linux.dev>
On Tue, Apr 21, 2026 at 05:23:49PM +0800, sunliming@linux.dev wrote:
> From: sunliming <sunliming@kylinos.cn>
>
> In the ovl_destroy_inode function, a variable reference oi->lowerdata_redirect
> that might be NULL is directly freed. Add a non-null check, and only free
> the space when it is not NULL.
Which NULL pointer dereferencing is that change supposed to prevent? If oi is
NULL, your condition would have exact same NULL pointer dereference (as would
several places in earlier lines, while we are at it).
And kfree(NULL) is NOT dereferencing anything; it's explicitly defined as
an empty operation, same as for userland free(NULL) and for the same reason.
prev parent reply other threads:[~2026-04-22 4:06 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-04-21 9:23 [PATCH] ovl: Fix possible NULL pointer dereference in ovl_destroy_inode sunliming
2026-04-21 9:45 ` Amir Goldstein
2026-04-21 11:37 ` sunliming
2026-04-22 4:10 ` Al Viro [this message]
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