linux-kernel - Re: [PATCH v3 1/3] jump_label: Prevent key->enabled int overflow

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Message-ID: <96cb7d74-a3e1-10d0-0af2-2b845b6da0ae@gmail.com>
Date:   Mon, 14 Nov 2022 17:13:51 +0000
From:   Dmitry Safonov <0x7f454c46@...il.com>
To:     Jason Baron <jbaron@...mai.com>, Dmitry Safonov <dima@...sta.com>,
        linux-kernel@...r.kernel.org, David Ahern <dsahern@...nel.org>,
        Eric Dumazet <edumazet@...gle.com>
Cc:     Bob Gilligan <gilligan@...sta.com>,
        "David S. Miller" <davem@...emloft.net>,
        Francesco Ruggeri <fruggeri@...sta.com>,
        Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Salam Noureddine <noureddine@...sta.com>,
        netdev@...r.kernel.org, Ard Biesheuvel <ardb@...nel.org>,
        Josh Poimboeuf <jpoimboe@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Steven Rostedt <rostedt@...dmis.org>
Subject: Re: [PATCH v3 1/3] jump_label: Prevent key->enabled int overflow

On 11/14/22 16:24, Jason Baron wrote:
> 
[..]
>> @@ -148,16 +167,23 @@ void static_key_slow_inc_cpuslocked(struct static_key *key)
>>  		 */
>>  		atomic_set_release(&key->enabled, 1);
>>  	} else {
>> -		atomic_inc(&key->enabled);
>> +		if (WARN_ON_ONCE(static_key_fast_inc(key))) {
> 
> Shouldn't that be negated to catch the overflow:
> 
> if (WARN_ON_ONCE(!static_key_fast_inc(key)))

Oh, that's just embarrassing!
I wonder how did I miss it during tests..

Thanks for spotting this, will fix in v4,
            Dmitry