For non-SMP, uses the new random canary value that is stored in the task struct whenever a new task is forked. Based on ARM version in df0698be14c6683606d5df2d83e3ae40f85ed0d9 and subject to the same limitations: the variable GCC expects, __stack_chk_guard, is global, so this will not work on SMP. Quoting Nicolas Pitre <nico@xxxxxxxxxxx>: "One way to overcome this GCC limitation would be to locate the __stack_chk_guard variable into a memory page of its own for each CPU, and then use TLB locking to have each CPU see its own page at the same virtual address for each of them." Signed-off-by: Gregory Fong <gregory.0xf0@xxxxxxxxx> --- arch/mips/kernel/asm-offsets.c | 3 +++ arch/mips/kernel/octeon_switch.S | 7 +++++++ arch/mips/kernel/r2300_switch.S | 7 +++++++ arch/mips/kernel/r4k_switch.S | 6 ++++++ 4 files changed, 23 insertions(+) This patch depends on patch "MIPS: initial stack protector support" (5448 in patchwork) I only have the hardware to test r4k. I don't see why it shouldn't work on r2300 and octeon as well, but it should probably be checked anyway. If some kind volunteers could verify r2300 and octeon, it'd be much appreciated! diff --git a/arch/mips/kernel/asm-offsets.c b/arch/mips/kernel/asm-offsets.c index 0845091..0c2e853 100644 --- a/arch/mips/kernel/asm-offsets.c +++ b/arch/mips/kernel/asm-offsets.c @@ -82,6 +82,9 @@ void output_task_defines(void) OFFSET(TASK_FLAGS, task_struct, flags); OFFSET(TASK_MM, task_struct, mm); OFFSET(TASK_PID, task_struct, pid); +#if defined(CONFIG_CC_STACKPROTECTOR) + OFFSET(TASK_STACK_CANARY, task_struct, stack_canary); +#endif DEFINE(TASK_STRUCT_SIZE, sizeof(struct task_struct)); BLANK(); } diff --git a/arch/mips/kernel/octeon_switch.S b/arch/mips/kernel/octeon_switch.S index 0e23343..94c29ec 100644 --- a/arch/mips/kernel/octeon_switch.S +++ b/arch/mips/kernel/octeon_switch.S @@ -98,6 +98,13 @@ mtc0 t0, $11,7 /* CvmMemCtl */ #endif 3: + +#if defined(CONFIG_CC_STACKPROTECTOR) && !defined(CONFIG_SMP) + PTR_L t8, __stack_chk_guard + LONG_L t9, TASK_STACK_CANARY(a1) + LONG_S t9, 0(t8) +#endif + /* * The order of restoring the registers takes care of the race * updating $28, $29 and kernelsp without disabling ints. diff --git a/arch/mips/kernel/r2300_switch.S b/arch/mips/kernel/r2300_switch.S index 5266c6e..38af83f 100644 --- a/arch/mips/kernel/r2300_switch.S +++ b/arch/mips/kernel/r2300_switch.S @@ -65,6 +65,13 @@ LEAF(resume) fpu_save_single a0, t0 # clobbers t0 1: + +#if defined(CONFIG_CC_STACKPROTECTOR) && !defined(CONFIG_SMP) + PTR_L t8, __stack_chk_guard + LONG_L t9, TASK_STACK_CANARY(a1) + LONG_S t9, 0(t8) +#endif + /* * The order of restoring the registers takes care of the race * updating $28, $29 and kernelsp without disabling ints. diff --git a/arch/mips/kernel/r4k_switch.S b/arch/mips/kernel/r4k_switch.S index 5e51219..921238a 100644 --- a/arch/mips/kernel/r4k_switch.S +++ b/arch/mips/kernel/r4k_switch.S @@ -68,6 +68,12 @@ # clobbers t1 1: +#if defined(CONFIG_CC_STACKPROTECTOR) && !defined(CONFIG_SMP) + PTR_L t8, __stack_chk_guard + LONG_L t9, TASK_STACK_CANARY(a1) + LONG_S t9, 0(t8) +#endif + /* * The order of restoring the registers takes care of the race * updating $28, $29 and kernelsp without disabling ints. -- 1.8.1.2
