On 01/19, Ravi Bangoria wrote:
>
> Probe on 2nd word of a prefixed instruction is invalid scenario and
> should be restricted.
I don't understand this ppc-specific problem, but...
> +#ifdef CONFIG_PPC64
> +int arch_uprobe_verify_opcode(struct page *page, unsigned long vaddr,
> + uprobe_opcode_t opcode)
> +{
> + uprobe_opcode_t prefix;
> + void *kaddr;
> + struct ppc_inst inst;
> +
> + /* Don't check if vaddr is pointing to the beginning of page */
> + if (!(vaddr & ~PAGE_MASK))
> + return 0;
So the fix is incomplete? Or insn at the start of page can't be prefixed?
> +int __weak arch_uprobe_verify_opcode(struct page *page, unsigned long vaddr,
> + uprobe_opcode_t opcode)
> +{
> + return 0;
> +}
> +
> static int verify_opcode(struct page *page, unsigned long vaddr,
> uprobe_opcode_t *new_opcode)
> {
> uprobe_opcode_t old_opcode;
> @@ -275,6 +281,8 @@ static int verify_opcode(struct page *page, unsigned long
> vaddr, uprobe_opcode_t
> if (is_swbp_insn(new_opcode)) {
> if (is_swbp) /* register: already installed? */
> return 0;
> + if (arch_uprobe_verify_opcode(page, vaddr, old_opcode))
> + return -EINVAL;
Well, this doesn't look good...
To me it would be better to change the prepare_uprobe() path to copy
the potential prefix into uprobe->arch and check ppc_inst_prefixed()
in arch_uprobe_analyze_insn(). What do you think?
Oleg.
