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Mon, 19 Jul 2021 00:51:23 -0700 (PDT) MIME-Version: 1.0 References: <20210719074538.9112-1-huangshaobo6@huawei.com> In-Reply-To: <20210719074538.9112-1-huangshaobo6@huawei.com> From: Ard Biesheuvel Date: Mon, 19 Jul 2021 09:51:11 +0200 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH] ARM: fix panic when kasan and kprobe are enabled To: Shaobo Huang Cc: andreyknvl@gmail.com, chenzefeng2@huawei.com, Dmitry Vyukov , Florian Fainelli , Alexander Potapenko , kasan-dev , kepler.chenxin@huawei.com, Linux ARM , Linux Kernel Mailing List , Russell King , liucheng32@huawei.com, Abbott Liu , nico@marvell.com, Xiaoming Ni , qbarnes@gmail.com, Andrey Ryabinin , sagar.abhishek@gmail.com, wuquanming@huawei.com, xiaoqian9@huawei.com, young.liuyang@huawei.com, zengweilin@huawei.com Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 19 Jul 2021 at 09:45, Shaobo Huang wrote: > > On Mon, 19 Jul 2021 at 07:06, Ard Biesheuvel wrote: > > On Mon, 19 Jul 2021 at 05:09, Shaobo Huang wrote: > > > > > > On Sat, 17 Jul 2021 at 01:01, Ard Biesheuvel wrote: > > > > On Wed, 14 Jul 2021 at 10:27, Shaobo Huang wrote: > > > >> > > > >> From: huangshaobo > > > >> > > > >> arm32 uses software to simulate the instruction replaced > > > >> by kprobe. some instructions may be simulated by constructing > > > >> assembly functions. therefore, before executing instruction > > > >> simulation, it is necessary to construct assembly function > > > >> execution environment in C language through binding registers. > > > >> after kasan is enabled, the register binding relationship will > > > >> be destroyed, resulting in instruction simulation errors and > > > >> causing kernel panic. > > > >> > > > >> the kprobe emulate instruction function is distributed in three > > > >> files: actions-common.c actions-arm.c actions-thumb.c, so disable > > > >> KASAN when compiling these files. > > > >> > > > >> for example, use kprobe insert on cap_capable+20 after kasan > > > >> enabled, the cap_capable assembly code is as follows: > > > >> : > > > >> e92d47f0 push {r4, r5, r6, r7, r8, r9, sl, lr} > > > >> e1a05000 mov r5, r0 > > > >> e280006c add r0, r0, #108 ; 0x6c > > > >> e1a04001 mov r4, r1 > > > >> e1a06002 mov r6, r2 > > > >> e59fa090 ldr sl, [pc, #144] ; > > > >> ebfc7bf8 bl c03aa4b4 <__asan_load4> > > > >> e595706c ldr r7, [r5, #108] ; 0x6c > > > >> e2859014 add r9, r5, #20 > > > >> ...... > > > >> The emulate_ldr assembly code after enabling kasan is as follows: > > > >> c06f1384 : > > > >> e92d47f0 push {r4, r5, r6, r7, r8, r9, sl, lr} > > > >> e282803c add r8, r2, #60 ; 0x3c > > > >> e1a05000 mov r5, r0 > > > >> e7e37855 ubfx r7, r5, #16, #4 > > > >> e1a00008 mov r0, r8 > > > >> e1a09001 mov r9, r1 > > > >> e1a04002 mov r4, r2 > > > >> ebf35462 bl c03c6530 <__asan_load4> > > > >> e357000f cmp r7, #15 > > > >> e7e36655 ubfx r6, r5, #12, #4 > > > >> e205a00f and sl, r5, #15 > > > >> 0a000001 beq c06f13bc > > > >> e0840107 add r0, r4, r7, lsl #2 > > > >> ebf3545c bl c03c6530 <__asan_load4> > > > >> e084010a add r0, r4, sl, lsl #2 > > > >> ebf3545a bl c03c6530 <__asan_load4> > > > >> e2890010 add r0, r9, #16 > > > >> ebf35458 bl c03c6530 <__asan_load4> > > > >> e5990010 ldr r0, [r9, #16] > > > >> e12fff30 blx r0 > > > >> e356000f cm r6, #15 > > > >> 1a000014 bne c06f1430 > > > >> e1a06000 mov r6, r0 > > > >> e2840040 add r0, r4, #64 ; 0x40 > > > >> ...... > > > >> > > > >> when running in emulate_ldr to simulate the ldr instruction, panic > > > >> occurred, and the log is as follows: > > > >> Unable to handle kernel NULL pointer dereference at virtual address > > > >> 00000090 > > > >> pgd = ecb46400 > > > >> [00000090] *pgd=2e0fa003, *pmd=00000000 > > > >> Internal error: Oops: 206 [#1] SMP ARM > > > >> PC is at cap_capable+0x14/0xb0 > > > >> LR is at emulate_ldr+0x50/0xc0 > > > >> psr: 600d0293 sp : ecd63af8 ip : 00000004 fp : c0a7c30c > > > >> r10: 00000000 r9 : c30897f4 r8 : ecd63cd4 > > > >> r7 : 0000000f r6 : 0000000a r5 : e59fa090 r4 : ecd63c98 > > > >> r3 : c06ae294 r2 : 00000000 r1 : b7611300 r0 : bf4ec008 > > > >> Flags: nZCv IRQs off FIQs on Mode SVC_32 ISA ARM Segment user > > > >> Control: 32c5387d Table: 2d546400 DAC: 55555555 > > > >> Process bash (pid: 1643, stack limit = 0xecd60190) > > > >> (cap_capable) from (kprobe_handler+0x218/0x340) > > > >> (kprobe_handler) from (kprobe_trap_handler+0x24/0x48) > > > >> (kprobe_trap_handler) from (do_undefinstr+0x13c/0x364) > > > >> (do_undefinstr) from (__und_svc_finish+0x0/0x30) > > > >> (__und_svc_finish) from (cap_capable+0x18/0xb0) > > > >> (cap_capable) from (cap_vm_enough_memory+0x38/0x48) > > > >> (cap_vm_enough_memory) from > > > >> (security_vm_enough_memory_mm+0x48/0x6c) > > > >> (security_vm_enough_memory_mm) from > > > >> (copy_process.constprop.5+0x16b4/0x25c8) > > > >> (copy_process.constprop.5) from (_do_fork+0xe8/0x55c) > > > >> (_do_fork) from (SyS_clone+0x1c/0x24) > > > >> (SyS_clone) from (__sys_trace_return+0x0/0x10) > > > >> Code: 0050a0e1 6c0080e2 0140a0e1 0260a0e1 (f801f0e7) > > > >> > > > >> Fixes: 35aa1df43283 ("ARM kprobes: instruction single-stepping support") > > > >> Fixes: 421015713b30 ("ARM: 9017/2: Enable KASan for ARM") > > > >> Signed-off-by: huangshaobo > > > >> Asked-by: Ard Biesheuvel > > > > > > > > Please don't do this - the maintainer will pick it up when applying, > > > > or when you send a new version of the patch, it is OK to add these > > > > tags if you have not made any substantial changes. > > > > > > > > But please do *not* add tags like this on someone else's behalf by > > > > replying to the email - and I should also point out that 'asked-by' is > > > > bogus. > > > > > > > > > > Hi ardb, > > > 1.The original patch you have been asked-by by email before, link: https://lore.kernel.org/linux-arm-kernel/CAMj1kXGqfF68MT4WwrxS0cYiUBb0gODDh-wGZSQcW9vxdfK90A@mail.gmail.com/ > > > > No it was not. > > > > It was ACKed by, not ASKed by. > > > > > 2.In addition to adding the asked-by tag, there is no other content modification in this patch > > > 3.The patch was reissued because the previous recipient did not include kasan maintainer and reviewers > > > > > > > I don't care. Do NOT reply to emails with tags in other people's names. > > > Hi ardb, > Sincerely apologize for my mistake, > I mistakenly wrote the Acked-by label as Asked-by. > Do I need to change to Acked-by or remove the label and reissue a patch? > You can put this patch into rmk's patch tracker at armlinux.org.uk. In this case, it is ok to include the tags that were given in reply, ie., my acked-by -- Ard. > > > > > thanks, > > > ShaoBo Huang > > > > > > > > > > >> --- > > > >> arch/arm/probes/kprobes/Makefile | 3 +++ > > > >> 1 file changed, 3 insertions(+) > > > >> > > > >> diff --git a/arch/arm/probes/kprobes/Makefile b/arch/arm/probes/kprobes/Makefile > > > >> index 14db56f49f0a..6159010dac4a 100644 > > > >> --- a/arch/arm/probes/kprobes/Makefile > > > >> +++ b/arch/arm/probes/kprobes/Makefile > > > >> @@ -1,4 +1,7 @@ > > > >> # SPDX-License-Identifier: GPL-2.0 > > > >> +KASAN_SANITIZE_actions-common.o := n > > > >> +KASAN_SANITIZE_actions-arm.o := n > > > >> +KASAN_SANITIZE_actions-thumb.o := n > > > >> obj-$(CONFIG_KPROBES) += core.o actions-common.o checkers-common.o > > > >> obj-$(CONFIG_ARM_KPROBES_TEST) += test-kprobes.o > > > >> test-kprobes-objs := test-core.o > > > >> -- > > > >> 2.12.3 > > > >>