Hi Mark, Ok, thanks for your help
Best regards, Chunhui Li -----邮件原件----- 发件人: Mark Rutland [mailto:mark.rutl...@arm.com] 发送时间: 2018年10月10日 17:26 收件人: Chunhui Li (李春辉) 抄送: Catalin Marinas; Will Deacon; Matthias Brugger; Marc Zyngier; Ard Biesheuvel; James Morse; Masahiro Yamada; linux-arm-ker...@lists.infradead.org; linux-kernel@vger.kernel.org; linux-media...@lists.infradead.org; wsd_upstream; Miles Chen (陳民樺); Walter-ZH Wu (吳祖寰); Yu Liang (梁宇); Nicholas Tang (鄭秦輝) 主题: Re: 答复: [PATCH] kasan: avoid out-of-bounds in unwind_frame On Wed, Oct 10, 2018 at 06:45:17AM +0000, Chunhui Li (李春辉) wrote: > Hi Mark, > > kasan detect out-of-bounds in stacktrace.c line 70, it's already over > READ_ONCE_NOCHECK, but still crash > kernel-4.9/arch/arm64/kernel/stacktrace.c > 69frame->sp = fp + 0x10; > 70frame->fp = READ_ONCE_NOCHECK(*(unsigned long *)(fp)); > > we test on Android platform, kernel-4.9 build with clang 6.0.2, we will do > experiment to clarify whether compiler related issue. > > READ_ONCE_NOCHECK->__read_once_size_nocheck with __no_sanitize_address > if enable CONFIG_KASAN > > kernel-4.9/include/linux/compiler-gcc.h > #define __no_sanitize_address __attribute__((no_sanitize_address)) > > kernel-4.9/include/linux/compiler-clang.h > #define __no_sanitize_address __attribute__((no_sanitize("address"))) If READ_ONCE_NOCHECK() isn't working as intended, then this is a compiler issue, and there are bigger problems regardless. If we need to workaround some compiler issue, that should be done in the implementation of READ_ONCE_NOCHECK(). Please note that there are other issues with using clang to compile the kernel; at minimum 7.0.0 is required to build a mainline kernel (and even then, the LSE atomics have to be explicitly disabled), so if this only affects 6.0.x, I don't think we need to carry any workaround upstream. > there is patch from internet, avoid kasan by wrapping with > kasan_disable_current, it seems better. > https://lore.kernel.org/patchwork/patch/644463 > such as: > +kasan_disable_current(); > // access fp > +kasan_enable_current(); Please note that the solution later in the thread [1] was to use READ_ONCE_NOCHECK(). Thanks, Mark. [1] https://lore.kernel.org/patchwork/patch/644463/#829858
