lkml.org 
[lkml]   [2013]   [Mar]   [24]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 3/7] uretprobes/x86: hijack return address
On 03/22, Anton Arapov wrote:
>
> +arch_uretprobe_hijack_return_addr(unsigned long 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;

Hmm.. I guess you need is_compat_task() here.

> + ncopied = copy_from_user(&orig_ret_vaddr, (void __user *)regs->sp, rasize);
> + if (unlikely(ncopied))
> + return -1;
> +
> + /* check whether address has been already hijacked */
> + if (orig_ret_vaddr == trampoline_vaddr)
> + return orig_ret_vaddr;
> +
> + ncopied = copy_to_user((void __user *)regs->sp, &trampoline_vaddr, rasize);
> + if (unlikely(ncopied)) {
> + if (ncopied != rasize) {
> + printk(KERN_ERR "uprobe: return address clobbered: "

Cosmetic, but we have pr_err().

> + "pid=%d, %%sp=%#lx, %%ip=%#lx\n",
> + current->pid, regs->sp, regs->ip);
> + /* kill task immediately */
> + send_sig(SIGSEGV, current, 0);

probably force_sig_info() makes more sense, but this is minor

> + }

You need to retun -1 here.

Cosmetic again, but since this function should be updated anyway,
I'd suggest

ncopied = copy_to_user(...);

if (likely(!ncopied))
return orig_ret_vaddr;

if (ncopied != rasize) {
...
}

return -1;

Oleg.



\
 
 \ /
  Last update: 2013-03-24 16:41    [W:0.226 / U:0.384 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site