Messages in this thread | | | Subject | Re: [PATCH] arm64: kasan: instrument user memory access API | From | "Shi, Yang" <> | Date | Fri, 27 May 2016 09:34:03 -0700 |
| |
On 5/27/2016 4:02 AM, Andrey Ryabinin wrote: > > > On 05/26/2016 09:43 PM, Yang Shi wrote: >> The upstream commit 1771c6e1a567ea0ba2cccc0a4ffe68a1419fd8ef >> ("x86/kasan: instrument user memory access API") added KASAN instrument to >> x86 user memory access API, so added such instrument to ARM64 too. >> >> Tested by test_kasan module. >> >> Signed-off-by: Yang Shi <yang.shi@linaro.org> >> --- >> arch/arm64/include/asm/uaccess.h | 18 ++++++++++++++++-- >> 1 file changed, 16 insertions(+), 2 deletions(-) > > Please, cover __copy_from_user() and __copy_to_user() too. > Unlike x86, your patch doesn't instrument these two.
I should elaborated this in my review. Yes, I did think about it, but unlike x86, __copy_to/from_user are implemented by asm code on ARM64. If I add kasan_check_read/write into them, I have to move the registers around to prepare the parameters for kasan calls, then restore them after the call, for example the below code for __copy_to_user:
mov x9, x0 mov x10, x1 mov x11, x2 mov x0, x10 mov x1, x11 bl kasan_check_read mov x0, x9 mov x1, x10
So, I'm wondering if it is worth or not since __copy_to/from_user are just called at a couple of places, i.e. sctp, a couple of drivers, etc and not used too much. Actually, I think some of them could be replaced by __copy_to/from_user_inatomic.
Any idea is appreciated.
Thanks, Yang
>
| |