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arm64: kprobes: Fix overflow when saving stack

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commit ab4c1325d4bf111a590a1f773e3d93bde7f40201 upstream.

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.

[dave.long@linaro.org: Since there is no irq_stack in this kernel version
this fix is not strictly necessary, but is included for completeness.]

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: David A. Long <dave.long@linaro.org>
This commit is contained in:
Marc Zyngier 2016-09-29 18:18:23 -04:00 • committed by Alex Shi
parent a1961c0da3
commit 71b5200f5f
1 changed files with 11 additions and 5 deletions
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16
arch/arm64/kernel/probes/kprobes.c
View file

@ -34,9 +34,6 @@
#include "decode-insn.h" #include "decode-insn.h"
#define MIN_STACK_SIZE(addr) min((unsigned long)MAX_STACK_SIZE, \
(unsigned long)current_thread_info() + THREAD_START_SP - (addr))
void jprobe_return_break(void); void jprobe_return_break(void);
DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL; DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL;
@ -45,6 +42,15 @@ DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk);
static void __kprobes static void __kprobes
post_kprobe_handler(struct kprobe_ctlblk *, struct pt_regs *); post_kprobe_handler(struct kprobe_ctlblk *, struct pt_regs *);
static inline unsigned long min_stack_size(unsigned long addr)
{
unsigned long size;
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) static void __kprobes arch_prepare_ss_slot(struct kprobe *p)
{ {
/* prepare insn slot */ /* prepare insn slot */
@ -492,7 +498,7 @@ int __kprobes setjmp_pre_handler(struct kprobe *p, struct pt_regs *regs)
* the argument area. * the argument area.
*/ */
memcpy(kcb->jprobes_stack, (void *)stack_ptr, 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); instruction_pointer_set(regs, (unsigned long) jp->entry);
preempt_disable(); preempt_disable();
@ -545,7 +551,7 @@ int __kprobes longjmp_break_handler(struct kprobe *p, struct pt_regs *regs)
unpause_graph_tracing(); unpause_graph_tracing();
*regs = kcb->jprobe_saved_regs; *regs = kcb->jprobe_saved_regs;
memcpy((void *)stack_addr, kcb->jprobes_stack, memcpy((void *)stack_addr, kcb->jprobes_stack,
MIN_STACK_SIZE(stack_addr)); min_stack_size(stack_addr));
preempt_enable_no_resched(); preempt_enable_no_resched();
return 1; return 1;
} }