From: Vincenzo Frascino <vincenzo.frascino@arm.com> To: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>, Catalin Marinas <catalin.marinas@arm.com>, Will Deacon <will@kernel.org>, Andrey Konovalov <andreyknvl@google.com>, Andrew Morton <akpm@linux-foundation.org> Subject: [PATCH] arm64: Fix warning in mte_get_random_tag() Date: Thu, 11 Feb 2021 12:56:02 +0000 [thread overview] Message-ID: <20210211125602.44248-1-vincenzo.frascino@arm.com> (raw) The simplification of mte_get_random_tag() caused the introduction of the warning below: In file included from arch/arm64/include/asm/kasan.h:9, from include/linux/kasan.h:16, from mm/kasan/common.c:14: mm/kasan/common.c: In function ‘mte_get_random_tag’: arch/arm64/include/asm/mte-kasan.h:45:9: warning: ‘addr’ is used uninitialized [-Wuninitialized] 45 | asm(__MTE_PREAMBLE "irg %0, %0" | Fix the warning initializing the address to NULL. Note: mte_get_random_tag() returns a tag and it never dereferences the address, hence 'addr' can be safely initialized to NULL. Fixes: c8f8de4c0887 ("arm64: kasan: simplify and inline MTE functions") Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will@kernel.org> Cc: Andrey Konovalov <andreyknvl@google.com> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com> --- This patch is based on linux-next/akpm arch/arm64/include/asm/mte-kasan.h | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/arch/arm64/include/asm/mte-kasan.h b/arch/arm64/include/asm/mte-kasan.h index 3d58489228c0..b2850b750726 100644 --- a/arch/arm64/include/asm/mte-kasan.h +++ b/arch/arm64/include/asm/mte-kasan.h @@ -40,7 +40,12 @@ static inline u8 mte_get_mem_tag(void *addr) /* Generate a random tag. */ static inline u8 mte_get_random_tag(void) { - void *addr; + /* + * mte_get_random_tag() returns a tag and it + * never dereferences the address, hence addr + * can be safely initialized to NULL. + */ + void *addr = NULL; asm(__MTE_PREAMBLE "irg %0, %0" : "+r" (addr)); -- 2.30.0
WARNING: multiple messages have this Message-ID (diff)
From: Vincenzo Frascino <vincenzo.frascino@arm.com> To: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com Cc: Catalin Marinas <catalin.marinas@arm.com>, Andrew Morton <akpm@linux-foundation.org>, Vincenzo Frascino <vincenzo.frascino@arm.com>, Will Deacon <will@kernel.org>, Andrey Konovalov <andreyknvl@google.com> Subject: [PATCH] arm64: Fix warning in mte_get_random_tag() Date: Thu, 11 Feb 2021 12:56:02 +0000 [thread overview] Message-ID: <20210211125602.44248-1-vincenzo.frascino@arm.com> (raw) The simplification of mte_get_random_tag() caused the introduction of the warning below: In file included from arch/arm64/include/asm/kasan.h:9, from include/linux/kasan.h:16, from mm/kasan/common.c:14: mm/kasan/common.c: In function ‘mte_get_random_tag’: arch/arm64/include/asm/mte-kasan.h:45:9: warning: ‘addr’ is used uninitialized [-Wuninitialized] 45 | asm(__MTE_PREAMBLE "irg %0, %0" | Fix the warning initializing the address to NULL. Note: mte_get_random_tag() returns a tag and it never dereferences the address, hence 'addr' can be safely initialized to NULL. Fixes: c8f8de4c0887 ("arm64: kasan: simplify and inline MTE functions") Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will@kernel.org> Cc: Andrey Konovalov <andreyknvl@google.com> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com> --- This patch is based on linux-next/akpm arch/arm64/include/asm/mte-kasan.h | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/arch/arm64/include/asm/mte-kasan.h b/arch/arm64/include/asm/mte-kasan.h index 3d58489228c0..b2850b750726 100644 --- a/arch/arm64/include/asm/mte-kasan.h +++ b/arch/arm64/include/asm/mte-kasan.h @@ -40,7 +40,12 @@ static inline u8 mte_get_mem_tag(void *addr) /* Generate a random tag. */ static inline u8 mte_get_random_tag(void) { - void *addr; + /* + * mte_get_random_tag() returns a tag and it + * never dereferences the address, hence addr + * can be safely initialized to NULL. + */ + void *addr = NULL; asm(__MTE_PREAMBLE "irg %0, %0" : "+r" (addr)); -- 2.30.0 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next reply other threads:[~2021-02-11 13:16 UTC|newest] Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-02-11 12:56 Vincenzo Frascino [this message] 2021-02-11 12:56 ` [PATCH] arm64: Fix warning in mte_get_random_tag() Vincenzo Frascino 2021-02-11 13:35 ` Ard Biesheuvel 2021-02-11 13:35 ` Ard Biesheuvel 2021-02-11 15:10 ` Vincenzo Frascino 2021-02-11 15:10 ` Vincenzo Frascino
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