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[209.85.220.65]) by mx.google.com with SMTPS id t4sor5565825pfl.69.2019.05.02.09.41.04 for (Google Transport Security); Thu, 02 May 2019 09:41:04 -0700 (PDT) Received-SPF: pass (google.com: domain of andreyknvl@google.com designates 209.85.220.65 as permitted sender) client-ip=209.85.220.65; Authentication-Results: mx.google.com; dkim=pass header.i=@google.com header.s=20161025 header.b=pW9Mlh00; spf=pass (google.com: domain of andreyknvl@google.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=andreyknvl@google.com; dmarc=pass (p=REJECT sp=REJECT dis=NONE) header.from=google.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=92karzGId4kTiPxbclHEQu/kjCIMGVKlDvLxWKLPllQ=; b=pW9Mlh00pTbPzKKMewhu5d9r6gm71AyCd5VE3PXTq9/6KeJWTWX9VAdyklQe4wuYb3 hw6/lCKfgP3MBQuvHSNTnDii93JeoAZ1tz36Ilk1XAnuH2tR8iS45vHy63ek7KeVo8Kv pPaZFSX+7KB1/bAO/KXNp2pKUm1C86PLwVWmBVtbE1JqIgA3KIcb1b/b7Ng6bjqelicY 6DQAN7is5Vz8aCc+ZcoCa9As2irNjbQGXPT3N7cDSP18s23973KvWfDy7jubbL2cvXcF 9fU8o6qOaaYqh7iOQW85PTkzEhusyPBLF2Ti3wgqhnyl9L/q3tU0Sq/+WyRxSAFHojV5 aVVQ== X-Google-Smtp-Source: APXvYqxEpi/34FQTQo/i2+QqbKQVsIw9n+cFj3zq5T2pXhuwK8N3k0YF3vpXL1+twKXJJwXv+Ny1FxDYEUV2ic9nRnQ= X-Received: by 2002:a62:46c7:: with SMTP id o68mr5390737pfi.54.1556815263742; Thu, 02 May 2019 09:41:03 -0700 (PDT) MIME-Version: 1.0 References: <20190502153538.2326-1-natechancellor@gmail.com> <20190502163057.6603-1-natechancellor@gmail.com> In-Reply-To: <20190502163057.6603-1-natechancellor@gmail.com> From: Andrey Konovalov Date: Thu, 2 May 2019 18:40:52 +0200 Message-ID: Subject: Re: [PATCH v2] kasan: Initialize tag to 0xff in __kasan_kmalloc To: Nathan Chancellor Cc: Andrey Ryabinin , Alexander Potapenko , Dmitry Vyukov , kasan-dev , Linux Memory Management List , LKML , Nick Desaulniers , clang-built-linux@googlegroups.com Content-Type: text/plain; charset="UTF-8" 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 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! > --- > > v1 -> v2: > > * Initialize tag to 0xff at Andrey's request > > mm/kasan/common.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/kasan/common.c b/mm/kasan/common.c > index 36afcf64e016..242fdc01aaa9 100644 > --- a/mm/kasan/common.c > +++ b/mm/kasan/common.c > @@ -464,7 +464,7 @@ static void *__kasan_kmalloc(struct kmem_cache *cache, const void *object, > { > unsigned long redzone_start; > unsigned long redzone_end; > - u8 tag; > + u8 tag = 0xff; > > if (gfpflags_allow_blocking(flags)) > quarantine_reduce(); > -- > 2.21.0 > > -- > You received this message because you are subscribed to the Google Groups "kasan-dev" group. > To unsubscribe from this group and stop receiving emails from it, send an email to kasan-dev+unsubscribe@googlegroups.com. > To post to this group, send email to kasan-dev@googlegroups.com. > To view this discussion on the web visit https://groups.google.com/d/msgid/kasan-dev/20190502163057.6603-1-natechancellor%40gmail.com. > For more options, visit https://groups.google.com/d/optout.