On Thu, Feb 28, 2013 at 12:00:11PM +0100, Anton Arapov wrote:
> hijack the return address and replace it with a "trampoline"
>
> v2:
> - remove ->doomed flag, kill task immediately
>
> Signed-off-by: Anton Arapov <an...@redhat.com>
> ---
> arch/x86/include/asm/uprobes.h | 1 +
> arch/x86/kernel/uprobes.c | 29 +++++++++++++++++++++++++++++
> 2 files changed, 30 insertions(+)
>
> diff --git a/arch/x86/include/asm/uprobes.h b/arch/x86/include/asm/uprobes.h
> index 8ff8be7..c353555 100644
> --- a/arch/x86/include/asm/uprobes.h
> +++ b/arch/x86/include/asm/uprobes.h
> @@ -55,4 +55,5 @@ extern int arch_uprobe_post_xol(struct arch_uprobe *aup,
> struct pt_regs *regs);
> extern bool arch_uprobe_xol_was_trapped(struct task_struct *tsk);
> extern int arch_uprobe_exception_notify(struct notifier_block *self,
> unsigned long val, void *data);
> extern void arch_uprobe_abort_xol(struct arch_uprobe *aup, struct pt_regs
> *regs);
> +extern unsigned long arch_uretprobe_hijack_return_addr(unsigned long
> rp_trampoline_vaddr, struct pt_regs *regs);
> #endif /* _ASM_UPROBES_H */
> diff --git a/arch/x86/kernel/uprobes.c b/arch/x86/kernel/uprobes.c
> index 0ba4cfb..85e2153 100644
> --- a/arch/x86/kernel/uprobes.c
> +++ b/arch/x86/kernel/uprobes.c
> @@ -697,3 +697,32 @@ bool arch_uprobe_skip_sstep(struct arch_uprobe *auprobe,
> struct pt_regs *regs)
> send_sig(SIGTRAP, current, 0);
> return ret;
> }
> +
> +extern unsigned long arch_uretprobe_hijack_return_addr(unsigned long
> + rp_trampoline_vaddr, struct pt_regs *regs)
> +{
> + int rasize, ncopied;
> + unsigned long orig_ret_vaddr = 0; /* clear high bits for 32-bit apps */
> +
> + rasize = is_ia32_task() ? 4 : 8;
> + ncopied = copy_from_user(&orig_ret_vaddr, (void __user *)regs->sp,
> rasize);
> + if (unlikely(ncopied))
What if ncopied < rasize? Agreed that the upper order bits can be 0, but should
you not validate ncopied == rasize?
Ananth
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