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| author |   Christophe Leroy <christophe.leroy@c-s.fr> | 2018-09-27 07:05:53 +0000 |
|---|---|---|
| committer |   Michael Ellerman <mpe@ellerman.id.au> | 2018-10-03 15:40:03 +1000 |
| commit | c3ff2a5193fa61b1b284cfb1d79628814ed0e95a (patch) | |
| tree | 042c4265fbe1dac941bd5c6c9d2079c1d8bdde14 /arch/powerpc/Makefile | |
| parent | powerpc/xive: Move a dereference below a NULL test (diff) | |
| download | linux-dev-c3ff2a5193fa61b1b284cfb1d79628814ed0e95a.tar.xz linux-dev-c3ff2a5193fa61b1b284cfb1d79628814ed0e95a.zip | |
powerpc/32: add stack protector support
This functionality was tentatively added in the past
(commit 6533b7c16ee5 ("powerpc: Initial stack protector
(-fstack-protector) support")) but had to be reverted
(commit f2574030b0e3 ("powerpc: Revert the initial stack
protector support") because of GCC implementing it differently
whether it had been built with libc support or not.
Now, GCC offers the possibility to manually set the
stack-protector mode (global or tls) regardless of libc support.
This time, the patch selects HAVE_STACKPROTECTOR only if
-mstack-protector-guard=tls is supported by GCC.
On PPC32, as register r2 points to current task_struct at
all time, the stack_canary located inside task_struct can be
used directly by using the following GCC options:
-mstack-protector-guard=tls
-mstack-protector-guard-reg=r2
-mstack-protector-guard-offset=offsetof(struct task_struct, stack_canary))
The protector is disabled for prom_init and bootx_init as
it is too early to handle it properly.
$ echo CORRUPT_STACK > /sys/kernel/debug/provoke-crash/DIRECT
[ 134.943666] Kernel panic - not syncing: stack-protector: Kernel stack is corrupted in: lkdtm_CORRUPT_STACK+0x64/0x64
[ 134.943666]
[ 134.955414] CPU: 0 PID: 283 Comm: sh Not tainted 4.18.0-s3k-dev-12143-ga3272be41209 #835
[ 134.963380] Call Trace:
[ 134.965860] [c6615d60] [c001f76c] panic+0x118/0x260 (unreliable)
[ 134.971775] [c6615dc0] [c001f654] panic+0x0/0x260
[ 134.976435] [c6615dd0] [c032c368] lkdtm_CORRUPT_STACK_STRONG+0x0/0x64
[ 134.982769] [c6615e00] [ffffffff] 0xffffffff
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Diffstat (limited to 'arch/powerpc/Makefile')
| -rw-r--r-- | arch/powerpc/Makefile | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile index 07d9dce7eda6..45b8eb4d8fe7 100644 --- a/arch/powerpc/Makefile +++ b/arch/powerpc/Makefile @@ -112,6 +112,9 @@ KBUILD_LDFLAGS += -m elf$(BITS)$(LDEMULATION) KBUILD_ARFLAGS += --target=elf$(BITS)-$(GNUTARGET) endif +cflags-$(CONFIG_STACKPROTECTOR) += -mstack-protector-guard=tls +cflags-$(CONFIG_STACKPROTECTOR) += -mstack-protector-guard-reg=r2 + LDFLAGS_vmlinux-y := -Bstatic LDFLAGS_vmlinux-$(CONFIG_RELOCATABLE) := -pie LDFLAGS_vmlinux := $(LDFLAGS_vmlinux-y) @@ -404,6 +407,13 @@ archclean: archprepare: checkbin +ifdef CONFIG_STACKPROTECTOR +prepare: stack_protector_prepare + +stack_protector_prepare: prepare0 + $(eval KBUILD_CFLAGS += -mstack-protector-guard-offset=$(shell awk '{if ($$2 == "TASK_CANARY") print $$3;}' include/generated/asm-offsets.h)) +endif + # Use the file '.tmp_gas_check' for binutils tests, as gas won't output # to stdout and these checks are run even on install targets. TOUT := .tmp_gas_check |