From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (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 29ED41F584C for ; Fri, 11 Apr 2025 15:34:14 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744385656; cv=none; b=Qj+Na/jd7WSvPOOgzCpI5kGnK4AZoktuKRCnSG9rw36SfaGhUtB4TWVmWrXAztvCYjM/aj22dxXkHtwUC27H3uTphf/vnQlW4BXVM+ruP5uBfbOl+/T6uDh92F0Y80un53VfyMeFrmO8zjWA6diQJ57N1ndfvNfv+jeTfoOfJkY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1744385656; c=relaxed/simple; bh=rG9dFgpUFs+9Utfiof1P9qMSsV1pNeVw+D8FvtrrL1Y=; h=From:In-Reply-To:References:To:Cc:Subject:MIME-Version: Content-Type:Date:Message-ID; b=hgZ+6+koTap5w2ESetqaDIYiyuJoNFAN4nUbK1oSLqIaulbQePNRkfaakNoxfVnvjx0ZMbWwKlR2gtVM+zsiy9/vS9C6Nhl3MwqqP1YeV8O8pOoMzBVT9q+TqAY9W+VoHSt7h+WcHm731QLGKODGY4GyZlBe8nf7HVgaIbXD/0w= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=OAny5Zre; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="OAny5Zre" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1744385654; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=YhYsOJdsfx866WPJGrSolHlP/LFfcf7OlKxeuxGvw9Y=; b=OAny5ZrectCBO8pjvkTDm/+8twImUlzkJYTcbjOtmGrfaiGT86VOJim7WsQAQFwmZM0sy2 kbCHYCLy/4Spaw9SQO2bM4Upq/YVZqcqEFaq+xOmfrGRDh9MJIIBqjHPvZVnVODv96Mtjk m5FoIPJ/fqZ26FP817pCZB+TRrDcujk= Received: from mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (ec2-35-165-154-97.us-west-2.compute.amazonaws.com [35.165.154.97]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-657-DFLz-8QhPbOMGRTUZG__Sg-1; Fri, 11 Apr 2025 11:34:10 -0400 X-MC-Unique: DFLz-8QhPbOMGRTUZG__Sg-1 X-Mimecast-MFC-AGG-ID: DFLz-8QhPbOMGRTUZG__Sg_1744385649 Received: from mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.12]) (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) (No client certificate requested) by mx-prod-mc-06.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 4D87018001F3; Fri, 11 Apr 2025 15:34:09 +0000 (UTC) Received: from warthog.procyon.org.uk (unknown [10.42.28.40]) by mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 29DEE19560AD; Fri, 11 Apr 2025 15:34:06 +0000 (UTC) Organization: Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 From: David Howells In-Reply-To: <20250410-fix_fs-v1-1-7c14ccc8ebaa@quicinc.com> References: <20250410-fix_fs-v1-1-7c14ccc8ebaa@quicinc.com> <20250410-fix_fs-v1-0-7c14ccc8ebaa@quicinc.com> To: Zijun Hu Cc: dhowells@redhat.com, Alexander Viro , Christian Brauner , Jan Kara , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Zijun Hu Subject: Re: [PATCH 1/5] fs/filesystems: Fix potential unsigned integer underflow in fs_name() 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-ID: <2425259.1744385645.1@warthog.procyon.org.uk> Date: Fri, 11 Apr 2025 16:34:05 +0100 Message-ID: <2425260.1744385645@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 Zijun Hu wrote: > fs_name() has @index as unsigned int, so there is underflow risk for > operation '@index--'. > > Fix by breaking the for loop when '@index == 0' which is also more proper > than '@index <= 0' for unsigned integer comparison. There isn't really a risk. The list walked by "tmp" and the checks that this is or is not NULL will prevent a problem. I also feel that breaking out of the loop with "<= 0" - even if the variable is unsigned - is safer, on the off chance that someone in the future changes the signedness of the variable. David