From b4657f7650babc9bfb41ce875abe41b18604a105 Mon Sep 17 00:00:00 2001 From: Jordan Niethe Date: Wed, 6 May 2020 13:40:47 +1000 Subject: [PATCH] powerpc/kprobes: Don't allow breakpoints on suffixes Do not allow inserting breakpoints on the suffix of a prefix instruction in kprobes. Signed-off-by: Jordan Niethe Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20200506034050.24806-28-jniethe5@gmail.com --- 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 33d54b0..227510d 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)); 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)) { + 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 -- 2.7.4