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Message-ID: <Y0leJgPmNrqeZP37@casper.infradead.org>
Date: Fri, 14 Oct 2022 14:03:34 +0100
From: Matthew Wilcox <willy@...radead.org>
To: Li zeming <zeming@...china.com>
Cc: krisman@...labora.com, linux-fsdevel@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH] unicode: mkutf8data: Add malloc return value detection
On Fri, Oct 14, 2022 at 03:57:10PM +0800, Li zeming wrote:
> Add the check and judgment statement of malloc return value.
Why? Just to shut up some static checker?
> +++ b/fs/unicode/mkutf8data.c
> @@ -495,6 +495,9 @@ static struct node *alloc_node(struct node *parent)
> int bitnum;
>
> node = malloc(sizeof(*node));
> + if (unlikely(!node))
> + return NULL;
> +
Right, so now alloc_node() can return NULL when it couldn't before.
Look at the callers ...
while (keybits) {
if (!*cursor)
*cursor = alloc_node(node);
node = *cursor;
if (node->nextbyte)
key++;
They're unprepared for alloc_node() to return NULL, so all you've done
is move the crash.
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