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[209.85.220.65]) by mx.google.com with SMTPS id br8sor6631601ejb.61.2019.05.22.18.47.35 for (Google Transport Security); Wed, 22 May 2019 18:47:35 -0700 (PDT) Received-SPF: pass (google.com: domain of natechancellor@gmail.com designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=RAHsstRp; spf=pass (google.com: domain of natechancellor@gmail.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=natechancellor@gmail.com; dmarc=pass (p=NONE sp=QUARANTINE dis=NONE) header.from=gmail.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=GhDOpD+a8hZjtMNIICSVb0siagk1dgNYZl1xyc8Nh/s=; b=RAHsstRpbLf3k0oQL3ZdAxZNnhWB9ZQx211cpf9TbvlO+3D6SP3+7mmzu0LlgM8ldM YwAGFs03guyR/13fWGrGfOdZTr/4PaK0iMdmiCPXcSlfRGUqpo8DxXbX92/urJpReydV ZjMcA3YzivAX4MdtizE4zM2cqlAYzaJ6ofb2Iz/tCiBMhFHhoO1Ln/GsI0hd8uSESLm5 ekrjS6LIpq+TSnewT23Yp7Fd825pMCcCj10h04CJZEpHj9FPgUqM+w5N50Bq50LoFzva QPaI8Irw+hkLdwcEis8BoraD6dx5NA7m5xWV/KpTMQpf0oBfAknVCAYX1XMfmXp0SvHg gpUQ== X-Google-Smtp-Source: APXvYqw/Jq1ILra5N4580sMe/IeEHxM9pGabgCBEXURpJwUD5K34xnviPekD1/bHpG4yUCsySFosJA== X-Received: by 2002:a17:906:488e:: with SMTP id v14mr33945656ejq.216.1558576055392; Wed, 22 May 2019 18:47:35 -0700 (PDT) Received: from archlinux-epyc ([2a01:4f9:2b:2b15::2]) by smtp.gmail.com with ESMTPSA id x22sm7584539edd.59.2019.05.22.18.47.34 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Wed, 22 May 2019 18:47:34 -0700 (PDT) Date: Wed, 22 May 2019 18:47:32 -0700 From: Nathan Chancellor To: Andrey Konovalov Cc: Andrey Ryabinin , Alexander Potapenko , Dmitry Vyukov , kasan-dev , Linux Memory Management List , LKML , Nick Desaulniers , clang-built-linux@googlegroups.com Subject: Re: [PATCH v2] kasan: Initialize tag to 0xff in __kasan_kmalloc Message-ID: <20190523014732.GA17640@archlinux-epyc> References: <20190502153538.2326-1-natechancellor@gmail.com> <20190502163057.6603-1-natechancellor@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.11.4 (2019-03-13) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, May 02, 2019 at 06:40:52PM +0200, Andrey Konovalov wrote: > On Thu, May 2, 2019 at 6:31 PM Nathan Chancellor > wrote: > > > > When building with -Wuninitialized and CONFIG_KASAN_SW_TAGS unset, Clang > > warns: > > > > mm/kasan/common.c:484:40: warning: variable 'tag' is uninitialized when > > used here [-Wuninitialized] > > kasan_unpoison_shadow(set_tag(object, tag), size); > > ^~~ > > > > set_tag ignores tag in this configuration but clang doesn't realize it > > at this point in its pipeline, as it points to arch_kasan_set_tag as > > being the point where it is used, which will later be expanded to > > (void *)(object) without a use of tag. Initialize tag to 0xff, as it > > removes this warning and doesn't change the meaning of the code. > > > > Link: https://github.com/ClangBuiltLinux/linux/issues/465 > > Signed-off-by: Nathan Chancellor > > Reviewed-by: Andrey Konovalov > > Thanks! > Thanks Andrey! Did anyone else have any other comments or can this be picked up? Cheers, Nathan