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 010401A5BBE; Wed, 20 Aug 2025 01:07:35 +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=1755652058; cv=none; b=c3COniuCV35winPC6n3mQmYWWK26HKFwQbW8+30Z23FiV7F/r48odMVB0aEvovtL0clV34BQvSZCQUlhTCMTci3r/6uuLqtyQSMK7ypFls/HK4KsrnVAqz9JXS+5K73wO0GfSf4iaHXICcWcRM2l5q0MyK9DnEX9w+3cTLEUK68= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755652058; c=relaxed/simple; bh=7k1sO4iEhovzZCGouVmIOXCPWu2hqIEKv/p30wza8KM=; h=Date:From:To:Cc:Subject:Message-Id:In-Reply-To:References: Mime-Version:Content-Type; b=Peg9/ieHxmEuxOb6ukW6SA41vNZjM41offM0Sa5yqCm/SjVpc/mNOjwA1xBo2lAO5FU1E0I64SC3pB2nYuBJX7ig/h/WqJZhsVYqB6sYn3/mawijjRm+E/CkwU5i/Ly3WkgvnYj0qsQcfdtuoL0DpFUbs0Hb6SAb7lxGDI21ZMs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=jm+YZY6+; 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="jm+YZY6+" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 55680C4CEF1; Wed, 20 Aug 2025 01:07:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1755652055; bh=7k1sO4iEhovzZCGouVmIOXCPWu2hqIEKv/p30wza8KM=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=jm+YZY6+eKEYj/dwKSFp7pLWmr4rLJJ+lwO++Ltrmw8KhMyMguxRDbf/jHiIyl/jb XRh3AtGTizFqz7pBQFHA1f9pwFiXWgmwaZkYVjvNCtT7PaDh9xtL2URYQ7vARarjb8 rtKaM1eJFl9yLS+i/ncdspn+Fwd0+HVjDn1h4wUsRGetXBR8dCz80At8Qngi6uSoD3 aMX9RnMBnWpOH0TBf6WA3MJ1YwTIsagJ1YrUSyErW5ReGUMVmE5rvccQSZ6jf6XZfU cuGJ8mmym1nPbWwFi90Sjl17oIRXs+F2lOosccdSBP4TS4p5KERRs9ESK9BLO8GY/f MVcLUl0XvQ3PQ== Date: Wed, 20 Aug 2025 10:07:31 +0900 From: Masami Hiramatsu (Google) To: Ben Hutchings Cc: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org Subject: Re: [PATCH] bootconfig: Fix negative seeks on 32-bit with LFS enabled Message-Id: <20250820100731.df29750fa21d864d18169d5c@kernel.org> In-Reply-To: References: X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Sun, 17 Aug 2025 16:21:46 +0200 Ben Hutchings wrote: > Commit 26dda5769509 "tools/bootconfig: Cleanup bootconfig footer size > calculations" replaced some expressions of type int with the > BOOTCONFIG_FOOTER_SIZE macro, which expands to an expression of type > size_t, which is unsigned. > > On 32-bit architectures with LFS enabled (i.e. off_t is 64-bit), the > seek offset of -BOOTCONFIG_FOOTER_SIZE now turns into a positive > value. Oops, I thought the sign bit would be extended. > > Fix this by casting the size to off_t before negating it. > > Just in case someone changes BOOTCONFIG_MAGIC_LEN to have type size_t > later, do the same thing to the seek offset of -BOOTCONFIG_MAGIC_LEN. > > Fixes: 26dda5769509 ("tools/bootconfig: Cleanup bootconfig footer size calculations") > Signed-off-by: Ben Hutchings Thanks for the fix! > --- > tools/bootconfig/main.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/tools/bootconfig/main.c b/tools/bootconfig/main.c > index 57c669d2aa90..55d59ed507d5 100644 > --- a/tools/bootconfig/main.c > +++ b/tools/bootconfig/main.c > @@ -193,7 +193,7 @@ static int load_xbc_from_initrd(int fd, char **buf) > if (stat.st_size < BOOTCONFIG_FOOTER_SIZE) > return 0; > > - if (lseek(fd, -BOOTCONFIG_MAGIC_LEN, SEEK_END) < 0) > + if (lseek(fd, -(off_t)BOOTCONFIG_MAGIC_LEN, SEEK_END) < 0) > return pr_errno("Failed to lseek for magic", -errno); > > if (read(fd, magic, BOOTCONFIG_MAGIC_LEN) < 0) > @@ -203,7 +203,7 @@ static int load_xbc_from_initrd(int fd, char **buf) > if (memcmp(magic, BOOTCONFIG_MAGIC, BOOTCONFIG_MAGIC_LEN) != 0) > return 0; > > - if (lseek(fd, -BOOTCONFIG_FOOTER_SIZE, SEEK_END) < 0) > + if (lseek(fd, -(off_t)BOOTCONFIG_FOOTER_SIZE, SEEK_END) < 0) > return pr_errno("Failed to lseek for size", -errno); > > if (read(fd, &size, sizeof(uint32_t)) < 0) -- Masami Hiramatsu (Google)