Le 06/05/2020 à 05:40, Jordan Niethe a écrit :
Do not allow inserting breakpoints on the suffix of a prefix instruction
in kprobes.
Signed-off-by: Jordan Niethe <jniet...@gmail.com>
---
v8: Add this back from v3
---
arch/powerpc/kernel/kprobes.c | 13 +++++++++++++
1 file changed, 13 insertions(+)
diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c
index 33d54b091c70..227510df8c55 100644
--- a/arch/powerpc/kernel/kprobes.c
+++ b/arch/powerpc/kernel/kprobes.c
@@ -106,7 +106,9 @@ kprobe_opcode_t *kprobe_lookup_name(const char *name,
unsigned int offset)
int arch_prepare_kprobe(struct kprobe *p)
{
int ret = 0;
+ struct kprobe *prev;
struct ppc_inst insn = ppc_inst_read((struct ppc_inst *)p->addr);
+ struct ppc_inst prefix = ppc_inst_read((struct ppc_inst *)(p->addr -
1));
What if p->addr is the first word of a page and the previous page is not mapped
?
if ((unsigned long)p->addr & 0x03) {
printk("Attempt to register kprobe at an unaligned address\n");
@@ -114,6 +116,17 @@ int arch_prepare_kprobe(struct kprobe *p)
} else if (IS_MTMSRD(insn) || IS_RFID(insn) || IS_RFI(insn)) {
printk("Cannot register a kprobe on rfi/rfid or mtmsr[d]\n");
ret = -EINVAL;
+ } else if (ppc_inst_prefixed(prefix)) {
If p->addr - 2 contains a valid prefixed instruction, then p->addr - 1 contains the suffix of that
prefixed instruction. Are we sure a suffix can never ever be misinterpreted as the prefix of a
prefixed instruction ?
+ printk("Cannot register a kprobe on the second word of prefixed
instruction\n");
+ ret = -EINVAL;
+ }
+ preempt_disable();
+ prev = get_kprobe(p->addr - 1);
+ preempt_enable_no_resched();
+ if (prev &&
+ ppc_inst_prefixed(ppc_inst_read((struct ppc_inst
*)prev->ainsn.insn))) {
+ printk("Cannot register a kprobe on the second word of prefixed
instruction\n");
+ ret = -EINVAL;
}
/* insn must be on a special executable page on ppc64. This is
