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Commit 2a6730c8 authored by Petr Mladek's avatar Petr Mladek Committed by Ingo Molnar
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kprobes/x86: Check for invalid ftrace location in __recover_probed_insn() 



__recover_probed_insn() should always be called from an address
where an instructions starts. The check for ftrace_location()
might help to discover a potential inconsistency.

This patch adds WARN_ON() when the inconsistency is detected.
Also it adds handling of the situation when the original code
can not get recovered.

Suggested-by: default avatarMasami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Signed-off-by: default avatarPetr Mladek <pmladek@suse.cz>
Cc: Ananth NMavinakayanahalli <ananth@in.ibm.com>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/r/1424441250-27146-3-git-send-email-pmladek@suse.cz


Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
parent 650b7b23

arch/x86/kernel/kprobes/core.c

+12 −0
Original line number Diff line number Diff line
@@ -227,6 +227,13 @@ __recover_probed_insn(kprobe_opcode_t *buf, unsigned long addr) 


	kp = get_kprobe((void *)addr);

	faddr = ftrace_location(addr);

	/*

	 * Addresses inside the ftrace location are refused by

	 * arch_check_ftrace_location(). Something went terribly wrong

	 * if such an address is checked here.

	 */

	if (WARN_ON(faddr && faddr != addr))

		return 0UL;

	/*

	 * Use the current code if it is not modified by Kprobe

	 * and it cannot be modified by ftrace.
@@ -265,6 +272,7 @@ __recover_probed_insn(kprobe_opcode_t *buf, unsigned long addr) 
 * Recover the probed instruction at addr for further analysis.

 * Caller must lock kprobes by kprobe_mutex, or disable preemption

 * for preventing to release referencing kprobes.

 * Returns zero if the instruction can not get recovered.

 */

unsigned long recover_probed_instruction(kprobe_opcode_t *buf, unsigned long addr)

{
@@ -299,6 +307,8 @@ static int can_probe(unsigned long paddr) 
		 * normally used, we just go through if there is no kprobe.

		 */

		__addr = recover_probed_instruction(buf, addr);

		if (!__addr)

			return 0;

		kernel_insn_init(&insn, (void *)__addr, MAX_INSN_SIZE);

		insn_get_length(&insn);
@@ -347,6 +357,8 @@ int __copy_instruction(u8 *dest, u8 *src) 
	unsigned long recovered_insn =

		recover_probed_instruction(buf, (unsigned long)src);



	if (!recovered_insn)

		return 0;

	kernel_insn_init(&insn, (void *)recovered_insn, MAX_INSN_SIZE);

	insn_get_length(&insn);

	/* Another subsystem puts a breakpoint, failed to recover */

arch/x86/kernel/kprobes/opt.c

+2 −0
Original line number Diff line number Diff line
@@ -259,6 +259,8 @@ static int can_optimize(unsigned long paddr) 
			 */

			return 0;

		recovered_insn = recover_probed_instruction(buf, addr);

		if (!recovered_insn)

			return 0;

		kernel_insn_init(&insn, (void *)recovered_insn, MAX_INSN_SIZE);

		insn_get_length(&insn);

		/* Another subsystem puts a breakpoint */