On 10/11/2017 02:36 PM, Florian Fainelli wrote: > On 10/11/2017 12:50 PM, Florian Fainelli wrote: >> On 10/11/2017 12:13 PM, Florian Fainelli wrote: >>> Hi Abbott, >>> >>> On 10/11/2017 01:22 AM, Abbott Liu wrote: >>>> Hi,all: >>>> These patches add arch specific code for kernel address sanitizer >>>> (see Documentation/kasan.txt). >>>> >>>> 1/8 of kernel addresses reserved for shadow memory. There was no >>>> big enough hole for this, so virtual addresses for shadow were >>>> stolen from user space. >>>> >>>> At early boot stage the whole shadow region populated with just >>>> one physical page (kasan_zero_page). Later, this page reused >>>> as readonly zero shadow for some memory that KASan currently >>>> don't track (vmalloc). >>>> >>>> After mapping the physical memory, pages for shadow memory are >>>> allocated and mapped. >>>> >>>> KASan's stack instrumentation significantly increases stack's >>>> consumption, so CONFIG_KASAN doubles THREAD_SIZE. >>>> >>>> Functions like memset/memmove/memcpy do a lot of memory accesses. >>>> If bad pointer passed to one of these function it is important >>>> to catch this. Compiler's instrumentation cannot do this since >>>> these functions are written in assembly. >>>> >>>> KASan replaces memory functions with manually instrumented variants. >>>> Original functions declared as weak symbols so strong definitions >>>> in mm/kasan/kasan.c could replace them. Original functions have aliases >>>> with '__' prefix in name, so we could call non-instrumented variant >>>> if needed. >>>> >>>> Some files built without kasan instrumentation (e.g. mm/slub.c). >>>> Original mem* function replaced (via #define) with prefixed variants >>>> to disable memory access checks for such files. >>>> >>>> On arm LPAE architecture, the mapping table of KASan shadow memory(if >>>> PAGE_OFFSET is 0xc0000000, the KASan shadow memory's virtual space is >>>> 0xb6e000000~0xbf000000) can't be filled in do_translation_fault function, >>>> because kasan instrumentation maybe cause do_translation_fault function >>>> accessing KASan shadow memory. The accessing of KASan shadow memory in >>>> do_translation_fault function maybe cause dead circle. So the mapping table >>>> of KASan shadow memory need be copyed in pgd_alloc function. >>>> >>>> >>>> Most of the code comes from: >>>> https://github.com/aryabinin/linux/commit/0b54f17e70ff50a902c4af05bb92716eb95acefe. >>> >>> Thanks for putting these patches together, I can't get a kernel to build >>> with ARM_LPAE=y or ARM_LPAE=n that does not result in the following: >>> >>> AS arch/arm/kernel/entry-common.o >>> arch/arm/kernel/entry-common.S: Assembler messages: >>> arch/arm/kernel/entry-common.S:53: Error: invalid constant >>> (ffffffffb6e00000) after fixup >>> arch/arm/kernel/entry-common.S:118: Error: invalid constant >>> (ffffffffb6e00000) after fixup >>> scripts/Makefile.build:412: recipe for target >>> 'arch/arm/kernel/entry-common.o' failed >>> make[3]: *** [arch/arm/kernel/entry-common.o] Error 1 >>> Makefile:1019: recipe for target 'arch/arm/kernel' failed >>> make[2]: *** [arch/arm/kernel] Error 2 >>> make[2]: *** Waiting for unfinished jobs.... >>> >>> This is coming from the increase in TASK_SIZE it seems. >>> >>> This is on top of v4.14-rc4-84-gff5abbe799e2 >> >> Seems like we can use the following to get through that build failure: >> >> diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S >> index 99c908226065..0de1160d136e 100644 >> --- a/arch/arm/kernel/entry-common.S >> +++ b/arch/arm/kernel/entry-common.S >> @@ -50,7 +50,13 @@ ret_fast_syscall: >> UNWIND(.cantunwind ) >> disable_irq_notrace @ disable interrupts >> ldr r2, [tsk, #TI_ADDR_LIMIT] >> +#ifdef CONFIG_KASAN >> + movw r1, #:lower16:TASK_SIZE >> + movt r1, #:upper16:TASK_SIZE >> + cmp r2, r1 >> +#else >> cmp r2, #TASK_SIZE >> +#endif >> blne addr_limit_check_failed >> ldr r1, [tsk, #TI_FLAGS] @ re-check for syscall >> tracing >> tst r1, #_TIF_SYSCALL_WORK | _TIF_WORK_MASK >> @@ -115,7 +121,13 @@ ret_slow_syscall: >> disable_irq_notrace @ disable interrupts >> ENTRY(ret_to_user_from_irq) >> ldr r2, [tsk, #TI_ADDR_LIMIT] >> +#ifdef CONFIG_KASAN >> + movw r1, #:lower16:TASK_SIZE >> + movt r1, #:upper16:TASK_SIZE >> + cmp r2, r1 >> +#else >> cmp r2, #TASK_SIZE >> +#endif >> blne addr_limit_check_failed >> ldr r1, [tsk, #TI_FLAGS] >> tst r1, #_TIF_WORK_MASK >> >> >> >> but then we will see another set of build failures with the decompressor >> code: >> >> WARNING: modpost: Found 2 section mismatch(es). >> To see full details build your kernel with: >> 'make CONFIG_DEBUG_SECTION_MISMATCH=y' >> KSYM .tmp_kallsyms1.o >> KSYM .tmp_kallsyms2.o >> LD vmlinux >> SORTEX vmlinux >> SYSMAP System.map >> OBJCOPY arch/arm/boot/Image >> Kernel: arch/arm/boot/Image is ready >> LDS arch/arm/boot/compressed/vmlinux.lds >> AS arch/arm/boot/compressed/head.o >> XZKERN arch/arm/boot/compressed/piggy_data >> CC arch/arm/boot/compressed/misc.o >> CC arch/arm/boot/compressed/decompress.o >> CC arch/arm/boot/compressed/string.o >> arch/arm/boot/compressed/decompress.c:51:0: warning: "memmove" redefined >> #define memmove memmove >> >> In file included from arch/arm/boot/compressed/decompress.c:7:0: >> ./arch/arm/include/asm/string.h:67:0: note: this is the location of the >> previous definition >> #define memmove(dst, src, len) __memmove(dst, src, len) >> >> arch/arm/boot/compressed/decompress.c:52:0: warning: "memcpy" redefined >> #define memcpy memcpy >> >> In file included from arch/arm/boot/compressed/decompress.c:7:0: >> ./arch/arm/include/asm/string.h:66:0: note: this is the location of the >> previous definition >> #define memcpy(dst, src, len) __memcpy(dst, src, len) >> >> SHIPPED arch/arm/boot/compressed/hyp-stub.S >> SHIPPED arch/arm/boot/compressed/fdt_rw.c >> SHIPPED arch/arm/boot/compressed/fdt.h >> SHIPPED arch/arm/boot/compressed/libfdt.h >> SHIPPED arch/arm/boot/compressed/libfdt_internal.h >> SHIPPED arch/arm/boot/compressed/fdt_ro.c >> SHIPPED arch/arm/boot/compressed/fdt_wip.c >> SHIPPED arch/arm/boot/compressed/fdt.c >> CC arch/arm/boot/compressed/atags_to_fdt.o >> SHIPPED arch/arm/boot/compressed/lib1funcs.S >> SHIPPED arch/arm/boot/compressed/ashldi3.S >> SHIPPED arch/arm/boot/compressed/bswapsdi2.S >> AS arch/arm/boot/compressed/hyp-stub.o >> CC arch/arm/boot/compressed/fdt_rw.o >> CC arch/arm/boot/compressed/fdt_ro.o >> CC arch/arm/boot/compressed/fdt_wip.o >> CC arch/arm/boot/compressed/fdt.o >> AS arch/arm/boot/compressed/lib1funcs.o >> AS arch/arm/boot/compressed/ashldi3.o >> AS arch/arm/boot/compressed/bswapsdi2.o >> AS arch/arm/boot/compressed/piggy.o >> LD arch/arm/boot/compressed/vmlinux >> arch/arm/boot/compressed/decompress.o: In function `fill_temp': >> /home/fainelli/dev/linux/arch/arm/boot/compressed/../../../../lib/xz/xz_dec_stream.c:162: >> undefined reference to `memcpy' >> arch/arm/boot/compressed/decompress.o: In function `bcj_flush': >> /home/fainelli/dev/linux/arch/arm/boot/compressed/../../../../lib/xz/xz_dec_bcj.c:404: >> undefined reference to `memcpy' >> /home/fainelli/dev/linux/arch/arm/boot/compressed/../../../../lib/xz/xz_dec_bcj.c:409: >> undefined reference to `memmove' >> arch/arm/boot/compressed/decompress.o: In function `lzma2_lzma': >> /home/fainelli/dev/linux/arch/arm/boot/compressed/../../../../lib/xz/xz_dec_lzma2.c:919: >> undefined reference to `memcpy' >> arch/arm/boot/compressed/decompress.o: In function `dict_flush': >> /home/fainelli/dev/linux/arch/arm/boot/compressed/../../../../lib/xz/xz_dec_lzma2.c:424: >> undefined reference to `memcpy' >> arch/arm/boot/compressed/decompress.o: In function `dict_uncompressed': >> /home/fainelli/dev/linux/arch/arm/boot/compressed/../../../../lib/xz/xz_dec_lzma2.c:390: >> undefined reference to `memcpy' >> /home/fainelli/dev/linux/arch/arm/boot/compressed/../../../../lib/xz/xz_dec_lzma2.c:400: >> undefined reference to `memcpy' >> arch/arm/boot/compressed/decompress.o: In function `lzma2_lzma': >> /home/fainelli/dev/linux/arch/arm/boot/compressed/../../../../lib/xz/xz_dec_lzma2.c:859: >> undefined reference to `memcpy' >> /home/fainelli/dev/linux/arch/arm/boot/compressed/../../../../lib/xz/xz_dec_lzma2.c:884: >> undefined reference to `memmove' >> arch/arm/boot/compressed/decompress.o: In function `xz_dec_bcj_run': >> /home/fainelli/dev/linux/arch/arm/boot/compressed/../../../../lib/xz/xz_dec_bcj.c:451: >> undefined reference to `memcpy' >> /home/fainelli/dev/linux/arch/arm/boot/compressed/../../../../lib/xz/xz_dec_bcj.c:471: >> undefined reference to `memcpy' >> arch/arm/boot/compressed/fdt_rw.o: In function `fdt_add_subnode_namelen': >> /home/fainelli/dev/linux/arch/arm/boot/compressed/fdt_rw.c:366: >> undefined reference to `__memset' >> arch/arm/boot/compressed/Makefile:182: recipe for target >> 'arch/arm/boot/compressed/vmlinux' failed >> make[4]: *** [arch/arm/boot/compressed/vmlinux] Error 1 >> arch/arm/boot/Makefile:53: recipe for target >> 'arch/arm/boot/compressed/vmlinux' failed >> make[3]: *** [arch/arm/boot/compressed/vmlinux] Error 2 > > I ended up fixing the redefinition warnings/build failures this way, but > I am not 100% confident this is the right fix: > > diff --git a/arch/arm/boot/compressed/decompress.c > b/arch/arm/boot/compressed/decompress.c > index f3a4bedd1afc..7d4a47752760 100644 > --- a/arch/arm/boot/compressed/decompress.c > +++ b/arch/arm/boot/compressed/decompress.c > @@ -48,8 +48,10 @@ extern int memcmp(const void *cs, const void *ct, > size_t count); > #endif > > #ifdef CONFIG_KERNEL_XZ > +#ifndef CONFIG_KASAN > #define memmove memmove > #define memcpy memcpy > +#endif > #include "../../../../lib/decompress_unxz.c" > #endif > > Was not able yet to track down why __memset is not being resolved, but > since I don't need them, disabled CONFIG_ATAGS and > CONFIG_ARM_ATAG_DTB_COMPAT and this allowed me to get a build working. > > This brought me all the way to a prompt and please find attached the > results of insmod test_kasan.ko for CONFIG_ARM_LPAE=y and > CONFIG_ARM_LPAE=n. Your patches actually spotted a genuine use after > free in one of our drivers (spi-bcm-qspi) so with this: > > Tested-by: Florian Fainelli <f.fainelli@xxxxxxxxx> > > Great job thanks! > The memset failure comes from the fact that the decompressor has its own string functions and there is an #undefine memset in there. The git history doesn't make it clear where this comes from but if I remove it the kernel at least compiles for me with the multi_v7_defconfig. Thanks, Laura -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
