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arm64: kprobes: Fix overflow when saving stack

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The MIN_STACK_SIZE macro tries evaluate how much stack space needs
to be saved in the jprobes_stack array, sized at 128 bytes.

When using the IRQ stack, said macro can happily return up to
IRQ_STACK_SIZE, which is 16kB. Mayhem follows.

This patch fixes things by getting rid of the crazy macro and
limiting the copy to be at most the size of the jprobes_stack
array, no matter which stack we're on.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Marc Zyngier 2016-07-20 17:46:58 +01:00 committed by Catalin Marinas
parent 44bd887ce1
commit ab4c1325d4
1 changed files with 14 additions and 8 deletions
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22
arch/arm64/kernel/probes/kprobes.c
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@ -34,12 +34,6 @@
#include "decode-insn.h"
#define MIN_STACK_SIZE(addr) (on_irq_stack(addr, raw_smp_processor_id()) ? \
min((unsigned long)IRQ_STACK_SIZE, \
IRQ_STACK_PTR(raw_smp_processor_id()) - (addr)) : \
min((unsigned long)MAX_STACK_SIZE, \
(unsigned long)current_thread_info() + THREAD_START_SP - (addr)))
void jprobe_return_break(void);
DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
@ -48,6 +42,18 @@ DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
static void __kprobes
post_kprobe_handler(struct kprobe_ctlblk *, struct pt_regs *);
static inline unsigned long min_stack_size(unsigned long addr)
{
unsigned long size;
if (on_irq_stack(addr, raw_smp_processor_id()))
size = IRQ_STACK_PTR(raw_smp_processor_id()) - addr;
else
size = (unsigned long)current_thread_info() + THREAD_START_SP - addr;
return min(size, FIELD_SIZEOF(struct kprobe_ctlblk, jprobes_stack));
}
static void __kprobes arch_prepare_ss_slot(struct kprobe *p)
{
/* prepare insn slot */
@ -495,7 +501,7 @@ int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
* the argument area.
*/
memcpy(kcb->jprobes_stack, (void *)stack_ptr,
MIN_STACK_SIZE(stack_ptr));
min_stack_size(stack_ptr));
instruction_pointer_set(regs, (unsigned long) jp->entry);
preempt_disable();
@ -548,7 +554,7 @@ int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
unpause_graph_tracing();
*regs = kcb->jprobe_saved_regs;
memcpy((void *)stack_addr, kcb->jprobes_stack,
MIN_STACK_SIZE(stack_addr));
min_stack_size(stack_addr));
preempt_enable_no_resched();
return 1;
}