linux-kernel - Re: [GIT PULL] ftrace: Check if pages were allocated before calling free

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Message-ID: <20210401160710.45a7a9b8@gandalf.local.home>
Date:   Thu, 1 Apr 2021 16:07:10 -0400
From:   Steven Rostedt <rostedt@...dmis.org>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [GIT PULL] ftrace: Check if pages were allocated before calling
 free_pages()

On Wed, 31 Mar 2021 11:03:21 -0700
Linus Torvalds <torvalds@...ux-foundation.org> wrote:

> @@ -6231,7 +6231,8 @@ static int ftrace_process_locs(struct module *mod,
>  		if (!addr)
>  			continue;
>  
> -		if (pg->index == pg->size) {
> +		end_offset = (pg->index+1) * sizeof(pg->records[0]);
> +		if (end_offset < PAGE_SIZE << pg->order) {

I believe that needs to be:

	if (end_offset >= PAGE_SIZE << pg->order) {

But as you said, you didn't test it. I'll look to see what else needs to be
fixed.

-- Steve


>  			/* We should have allocated enough */
>  			if (WARN_ON(!pg->next))
>  				break;