From: Andrey Ryabinin <aryabinin@virtuozzo.com>
To: Arnd Bergmann <arnd@arndb.de>, Dmitry Vyukov <dvyukov@google.com>
Cc: "kasan-dev@googlegroups.com" <kasan-dev@googlegroups.com>,
Alexander Potapenko <glider@google.com>,
<linux-kernel@vger.kernel.org>,
Christian Borntraeger <borntraeger@de.ibm.com>
Subject: Re: [RFC] kasan stack overflow warnings again: READ_ONCE(), typecheck()
Date: Wed, 15 Feb 2017 17:19:49 +0300 [thread overview]
Message-ID: <d3ed1833-d22f-2501-6820-6de579bf35f0@virtuozzo.com> (raw)
In-Reply-To: <36862803-f365-6ab4-198e-e858f41ee914@virtuozzo.com>
On 02/15/2017 05:06 PM, Andrey Ryabinin wrote:
> diff --git a/include/linux/compiler.h b/include/linux/compiler.h
> index 10bca12..5d9dd63 100644
> --- a/include/linux/compiler.h
> +++ b/include/linux/compiler.h
> @@ -301,10 +301,10 @@ static __always_inline void __write_once_size(volatile void *p, void *res, int s
> */
>
> #define __READ_ONCE(x, check) \
> - __builtin_choose_expr(sizeof(x) == 1, *(volatile typeof(&(x)))&(x), \
> - __builtin_choose_expr(sizeof(x) == 2, *(volatile typeof(&(x)))&(x), \
> - __builtin_choose_expr(sizeof(x) == 4, *(volatile typeof(&(x)))&(x), \
> - __builtin_choose_expr(sizeof(x) == sizeof(long), *(volatile typeof(&(x)))&(x), \
> + __builtin_choose_expr(sizeof(x) == 1, (typeof(x))(__u64)*(volatile __u8 *)&(x), \
> + __builtin_choose_expr(sizeof(x) == 2, (typeof(x))(__u64)*(volatile __u16 *)&(x), \
> + __builtin_choose_expr(sizeof(x) == 4, (typeof(x))(__u64)*(volatile __u32 *)&(x), \
> + __builtin_choose_expr(sizeof(x) == 8, (typeof(x))(__u64)*(volatile __u64 *)&(x), \
> ({union { typeof(x) __val; char __c[1]; } __u; \
> if (check) \
> __read_once_size(&(x), __u.__c, sizeof(x)); \
Scratch this, it doesn't work:
../arch/x86/mm/gup.c:20:2: error: conversion to non-scalar type requested
return READ_ONCE(*ptep);
^
next prev parent reply other threads:[~2017-02-15 14:18 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-02-14 23:03 Arnd Bergmann
2017-02-15 9:18 ` Dmitry Vyukov
2017-02-15 10:34 ` Arnd Bergmann
2017-02-15 22:31 ` Arnd Bergmann
2017-02-15 14:06 ` Andrey Ryabinin
2017-02-15 14:19 ` Andrey Ryabinin [this message]
2017-02-15 16:18 ` Christian Borntraeger
2017-02-15 16:20 ` Christian Borntraeger
2017-02-15 22:19 ` Arnd Bergmann
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