Messages in this thread | | | Date | Mon, 12 Jul 2021 09:37:17 +0100 | From | Mark Rutland <> | Subject | Re: [PATCH] kasan: fix build for CONFIG_KASAN_HW_TAGS |
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On Sat, Jul 10, 2021 at 09:16:14PM +0200, Andrey Konovalov wrote: > On Thu, Jul 8, 2021 at 4:44 PM Mark Rutland <mark.rutland@arm.com> wrote: > > > > When CONFIG_KASAN_HW_TAGS is selected, <linux/kasan.h> uses _RET_IP_, > > but doesn't explicitly include <linux/kernel.h> where this is defined. > > > > We used to get this via a transitive include, but since commit: > > > > f39650de687e3576 ("kernel.h: split out panic and oops helpers") > > > > ... this is no longer the case, and so we get a build failure: > > > > | CC arch/arm64/mm/kasan_init.o > > | In file included from arch/arm64/mm/kasan_init.c:10: > > | ./include/linux/kasan.h: In function 'kasan_slab_free': > > | ./include/linux/kasan.h:211:39: error: '_RET_IP_' undeclared (first use in this function) > > | 211 | return __kasan_slab_free(s, object, _RET_IP_, init); > > | | ^~~~~~~~ > > | ./include/linux/kasan.h:211:39: note: each undeclared identifier is reported only once for each function it appears in > > | ./include/linux/kasan.h: In function 'kasan_kfree_large': > > | ./include/linux/kasan.h:219:28: error: '_RET_IP_' undeclared (first use in this function) > > | 219 | __kasan_kfree_large(ptr, _RET_IP_); > > | | ^~~~~~~~ > > | ./include/linux/kasan.h: In function 'kasan_slab_free_mempool': > > | ./include/linux/kasan.h:226:34: error: '_RET_IP_' undeclared (first use in this function) > > | 226 | __kasan_slab_free_mempool(ptr, _RET_IP_); > > | | ^~~~~~~~ > > | ./include/linux/kasan.h: In function 'kasan_check_byte': > > | ./include/linux/kasan.h:277:35: error: '_RET_IP_' undeclared (first use in this function) > > | 277 | return __kasan_check_byte(addr, _RET_IP_); > > | | ^~~~~~~~ > > > > Fix this by including <linux/kernel.h> explicitly. > > Hi Mark, > > Marco already sent a fix for this. It should be in the mm tree. > (Although the link to it in the Andrew's notification email doesn't > work. But they rarely do :) > > > As a heads-up, there are some unrelated runtime issues with > > CONFIG_KASAN_HW_TAGS and the recent arm64 string routines rework, which > > I'm looking into now. If you boot-test with this applied, you should > > expect to see those. > > +Sam, +Robin > > Looks like the new strlen routine is making accesses past the allocated buffer. > > The guilty commit is 325a1de81287 ("arm64: Import updated version of > Cortex Strings' strlen").
FWIW, I already have a fix for this, I'm just cleaning it up and will post shortly.
The issue is that the new strlen() will make unaligned 16-byte accesses within a naturally-aligned 4096-byte window and over-read by up to 15 bytes; we can fiddle with its alignment fixup to always align to 16 bytes when MTE is in use so any over-read is within the same MTE granule as the final byte of the string.
I've checked the other routines, and AFAICT they never make accesses which staddle a 16-byte boundary.
Thanks, Mark.
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