From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 31429213E67; Thu, 15 May 2025 15:29:55 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747322996; cv=none; b=s8kbzyL+rYrtKRBkk7VQYa7hsgImsLjVYDRFFtdJt+IZUuWp3lk7BleFZV12WopO/BYJn3SlT/hzFNCC3KbAD6Bb2bvsid5szzxTiH635M+HgL8luAp/2cF7MjN7WXrYC3fTwO9jaOBgWVCNEU+LYBwMyAxtBTq9Tt3HI+b45HM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747322996; c=relaxed/simple; bh=r+vgoHyPQBXrDnAequwJxZxOTi6XM4s7SidDK1toDMU=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=nX94czfAn2YQXl0CrCi488J6Eq3+zPodR3J39F6UX4iN6vkkvM31u3V7ZsSOa2eaVidg6I2BVe/PTXaNQkT9BI0OqBPkWa5yFpgF3CC+5Bo3mk+dcDfbdnoubQ7K27tPtGJ6ZfJ/1356bFQXX4Q0gF+Qv1uzxbOGcIw8lnhnAB0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=UzEkXjNf; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="UzEkXjNf" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 88415C4CEE7; Thu, 15 May 2025 15:29:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1747322995; bh=r+vgoHyPQBXrDnAequwJxZxOTi6XM4s7SidDK1toDMU=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=UzEkXjNfRDfzQ5GSc7NDBYXzLq2U2bw/Gp4vlC7jEmo5kdO/vJmkmRqKjBbvtvSHE IpmoYfwa4Yw2qifam3LOs0zBS1KEzYLQhiFDffdShYwPtRqVZdiEycadwv7r+PYk5h F4VQ5ffWzzIpOVhb5ugdL/SHgPikVYUBu3BQB8RlWW9b5RVdNuZdwYR/j3G2vIqYqj 326h4/FYdiMslKMxeL1TVkHX4WyXFkMbVQsztMT2WgWln04f/pMRIiiyzSARV6zxqK 9VzzFrxMxdRi85vDhkSPA6Gs6VcIhSvLUzfyL3pZKhpVKV1IfIDw4C5nguWIlY7ZYC lGmUajFVTt6Uw== Date: Thu, 15 May 2025 17:29:50 +0200 From: Ingo Molnar To: "Xin Li (Intel)" Cc: linux-kernel@vger.kernel.org, xen-devel@lists.xenproject.org, linux-acpi@vger.kernel.org, tglx@linutronix.de, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, peterz@infradead.org, jgross@suse.com, boris.ostrovsky@oracle.com, rafael@kernel.org, lenb@kernel.org Subject: Re: [PATCH v1 2/3] x86/xen/msr: Fix uninitialized symbol 'err' Message-ID: References: <20250512084552.1586883-1-xin@zytor.com> <20250512084552.1586883-3-xin@zytor.com> Precedence: bulk X-Mailing-List: linux-acpi@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250512084552.1586883-3-xin@zytor.com> * Xin Li (Intel) wrote: > xen_read_msr_safe() currently passes an uninitialized argument err to > xen_do_read_msr(). But as xen_do_read_msr() may not set the argument, > xen_read_msr_safe() could return err with an unpredictable value. > > To ensure correctness, initialize err to 0 (representing success) > in xen_read_msr_safe(). > > Because xen_read_msr_safe() is essentially a wrapper of xen_do_read_msr(), > the latter should be responsible for initializing the value of *err to 0. > Thus initialize *err to 0 in xen_do_read_msr(). > > Fixes: 502ad6e5a619 ("x86/msr: Change the function type of native_read_msr_safe()") > Reported-by: Dan Carpenter > Closes: https://lore.kernel.org/xen-devel/aBxNI_Q0-MhtBSZG@stanley.mountain/ > Signed-off-by: Xin Li (Intel) > --- > arch/x86/xen/enlighten_pv.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c > index 3be38350f044..01f1d441347e 100644 > --- a/arch/x86/xen/enlighten_pv.c > +++ b/arch/x86/xen/enlighten_pv.c > @@ -1091,6 +1091,9 @@ static u64 xen_do_read_msr(u32 msr, int *err) > { > u64 val = 0; /* Avoid uninitialized value for safe variant. */ > > + if (err) > + *err = 0; > + > if (pmu_msr_chk_emulated(msr, &val, true)) > return val; > > @@ -1162,7 +1165,7 @@ static void xen_do_write_msr(u32 msr, u64 val, int *err) > > static int xen_read_msr_safe(u32 msr, u64 *val) > { > - int err; > + int err = 0; > > *val = xen_do_read_msr(msr, &err); > return err; So why not initialize 'err' with 0 in both callers, xen_read_msr_safe() and xen_read_msr(), and avoid all the initialization trouble in xen_do_read_msr()? Thanks, Ingo