From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bedivere.hansenpartnership.com (bedivere.hansenpartnership.com [96.44.175.130]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 84DA1193409; Tue, 22 Oct 2024 14:30:21 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=96.44.175.130 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729607423; cv=none; b=QJqaJB/LNiR0kVdcwLXtghCnov9m7RDIUWugLsFbmJMFvhtfeox1RYEdlgVjJVyP7+Bdx2krhXatCXMSmzlhXdwvQxxrX9YDT+w9YpPEXbgxIO3o7kpuGP8T6bhl0Pgguq+mHbzPp4j76M2l3VoennyxlglPzrKINtfEBTAfFuw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1729607423; c=relaxed/simple; bh=DbP90FxVvhBKxKThPAzJkk4pXIl4TgkL0n/XjlVZekg=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=DHA/e7OBNRXcJHXIC97lWX/TLFT72mzJdWhWN7zyQ3wCKA77b902gF6qUISQTHH6YpquHJcJ79yet1n9WrTTtr4mlj610rLxlSu5oShrg4uZ67VOZeJId6Zwa5maV9BdCJXwlNqCSNpA1IaeEyt9Z/Edepdif+UmyEdVCfS6VSc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=HansenPartnership.com; spf=pass smtp.mailfrom=HansenPartnership.com; dkim=pass (1024-bit key) header.d=hansenpartnership.com header.i=@hansenpartnership.com header.b=Wc6BaGvN; dkim=pass (1024-bit key) header.d=hansenpartnership.com header.i=@hansenpartnership.com header.b=Wc6BaGvN; arc=none smtp.client-ip=96.44.175.130 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=HansenPartnership.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=HansenPartnership.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=hansenpartnership.com header.i=@hansenpartnership.com header.b="Wc6BaGvN"; dkim=pass (1024-bit key) header.d=hansenpartnership.com header.i=@hansenpartnership.com header.b="Wc6BaGvN" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=hansenpartnership.com; s=20151216; t=1729607420; bh=DbP90FxVvhBKxKThPAzJkk4pXIl4TgkL0n/XjlVZekg=; h=Message-ID:Subject:From:To:Date:In-Reply-To:References:From; b=Wc6BaGvNouFj2aadVuF6qds8MoCDSn/WSrQhuJu/8w8bzq6sAz2EamkUlM0dbuB2E lyfGkuqnp1/7a3J2ApgThqbBK3jYvMKZUTyREzPjSPUKBBif4yRpdvzIfUByNluHuP ahFvHP8fwp9EUmfdq3Fn2jhm3l8RwTnBf8VqFW9I= Received: from localhost (localhost [127.0.0.1]) by bedivere.hansenpartnership.com (Postfix) with ESMTP id 9887F1286339; Tue, 22 Oct 2024 10:30:20 -0400 (EDT) Received: from bedivere.hansenpartnership.com ([127.0.0.1]) by localhost (bedivere.hansenpartnership.com [127.0.0.1]) (amavis, port 10024) with ESMTP id Oh7LZV33Y85V; Tue, 22 Oct 2024 10:30:20 -0400 (EDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=hansenpartnership.com; s=20151216; t=1729607420; bh=DbP90FxVvhBKxKThPAzJkk4pXIl4TgkL0n/XjlVZekg=; h=Message-ID:Subject:From:To:Date:In-Reply-To:References:From; b=Wc6BaGvNouFj2aadVuF6qds8MoCDSn/WSrQhuJu/8w8bzq6sAz2EamkUlM0dbuB2E lyfGkuqnp1/7a3J2ApgThqbBK3jYvMKZUTyREzPjSPUKBBif4yRpdvzIfUByNluHuP ahFvHP8fwp9EUmfdq3Fn2jhm3l8RwTnBf8VqFW9I= Received: from lingrow.int.hansenpartnership.com (unknown [IPv6:2601:5c4:4302:c21::a774]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (Client did not present a certificate) by bedivere.hansenpartnership.com (Postfix) with ESMTPSA id 5C3BD128623B; Tue, 22 Oct 2024 10:30:19 -0400 (EDT) Message-ID: Subject: Re: [PATCH] lib: string_helpers: fix potential snprintf() output truncation From: James Bottomley To: Rasmus Villemoes , Andy Shevchenko Cc: Jiri Slaby , Bartosz Golaszewski , Kees Cook , Andy Shevchenko , Andrew Morton , Greg KH , linux-hardening@vger.kernel.org, linux-kernel@vger.kernel.org, Bartosz Golaszewski , stable@vger.kernel.org Date: Tue, 22 Oct 2024 10:30:18 -0400 In-Reply-To: <87y12gp7xb.fsf@prevas.dk> References: <20241021100421.41734-1-brgl@bgdev.pl> <87y12gp7xb.fsf@prevas.dk> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.42.4 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit On Tue, 2024-10-22 at 15:46 +0200, Rasmus Villemoes wrote: [...] > -       snprintf(buf, len, "%u%s %s", (u32)size, > -                tmp, unit); > +       if (j) > +               snprintf(buf, len, "%u.%03u %s", (u32)size, > remainder, unit); > +       else > +               snprintf(buf, len, "%u %s", (u32)size, unit); >  } >  EXPORT_SYMBOL(string_get_size); Where are you getting this from? The current statement you'd be replacing is return snprintf(buf, len, "%u%s%s%s%s", (u32)size, tmp, (units & STRING_UNITS_NO_SPACE) ? "" : " ", unit, (units & STRING_UNITS_NO_BYTES) ? "" : "B"); The use of a tmp buffer prevents that having to be repeated. If we had a way of specifying "ignore argument" I suppose we could switch the format string on J and then only have a single statement. Regards, James