linux-kernel - Re: [PATCH] objtool: Fix off-by-one in symbol_by

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Date:   Fri, 3 Apr 2020 09:50:44 -0500
From:   Josh Poimboeuf <jpoimboe@...hat.com>
To:     Julien Thierry <jthierry@...hat.com>
Cc:     linux-kernel@...r.kernel.org, peterz@...radead.org, mbenes@...e.cz
Subject: Re: [PATCH] objtool: Fix off-by-one in symbol_by_offset()

On Fri, Apr 03, 2020 at 02:17:30PM +0100, Julien Thierry wrote:
> Sometimes, WARN_FUNC() and other users of symbol_by_offset() will
> associate the first instruction of a symbol with the symbol preceding
> it.
> This is because symbol->offset + symbol->len is already outside of the
> symbol's range.
> 
> Signed-off-by: Julien Thierry <jthierry@...hat.com>
> ---
>  tools/objtool/elf.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/tools/objtool/elf.c b/tools/objtool/elf.c
> index 09ddc8f1def3..c4857fa3f1d1 100644
> --- a/tools/objtool/elf.c
> +++ b/tools/objtool/elf.c
> @@ -105,7 +105,7 @@ static int symbol_by_offset(const void *key, const struct rb_node *node)
>  
>  	if (*o < s->offset)
>  		return -1;
> -	if (*o > s->offset + s->len)
> +	if (*o >= s->offset + s->len)
>  		return 1;
>  
>  	return 0;

Thanks - looks like this fixes 2a362ecc3ec9 ("objtool: Optimize
find_symbol_*() and read_symbols()").

-- 
Josh