Messages in this thread | | | From | Ard Biesheuvel <> | Date | Mon, 19 Jul 2021 09:06:57 +0200 | Subject | Re: [PATCH] ARM: fix panic when kasan and kprobe are enabled |
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On Mon, 19 Jul 2021 at 05:09, Shaobo Huang <huangshaobo6@huawei.com> wrote: > > On Sat, 17 Jul 2021 at 01:01, Ard Biesheuvel <ardb@kernel.org> wrote: > > On Wed, 14 Jul 2021 at 10:27, Shaobo Huang <huangshaobo6@huawei.com> wrote: > >> > >> From: huangshaobo <huangshaobo6@huawei.com> > >> > >> 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: > >> <cap_capable>: > >> 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 <emulate_ldr>: > >> 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 <emulate_ldr+0x38> > >> 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 <emulate_ldr+0xac> > >> 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 <huangshaobo6@huawei.com> > >> Asked-by: Ard Biesheuvel <ardb@kernel.org> > > > > 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.
> 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 > >>
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