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Commit 791eca10 authored by Anton Arapov's avatar Anton Arapov Committed by Oleg Nesterov
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uretprobes/x86: Hijack return address 



Hijack the return address and replace it with a trampoline address.

Signed-off-by: default avatarAnton Arapov <anton@redhat.com>
Acked-by: default avatarSrikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
parent e78aebfd

arch/x86/include/asm/uprobes.h

+1 −0
Original line number Diff line number Diff line
@@ -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 trampoline_vaddr, struct pt_regs *regs);

#endif	/* _ASM_UPROBES_H */

arch/x86/kernel/uprobes.c

+29 −0
Original line number Diff line number Diff line
@@ -697,3 +697,32 @@ bool arch_uprobe_skip_sstep(struct arch_uprobe *auprobe, struct pt_regs *regs) 
		send_sig(SIGTRAP, current, 0);

	return ret;

}



unsigned long

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;

	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 (likely(!ncopied))

		return orig_ret_vaddr;



	if (ncopied != rasize) {

		pr_err("uprobe: return address clobbered: pid=%d, %%sp=%#lx, "

			"%%ip=%#lx\n", current->pid, regs->sp, regs->ip);



		force_sig_info(SIGSEGV, SEND_SIG_FORCED, current);

	}



	return -1;

}