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Commit a00e817f authored by Masami Hiramatsu's avatar Masami Hiramatsu Committed by Frederic Weisbecker
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kprobes/x86-32: Move irq-exit functions to kprobes section 



Move irq-exit functions to .kprobes.text section to protect against
kprobes recursion.

When I ran kprobe stress test on x86-32, I found below symbols
cause unrecoverable recursive probing:

	ret_from_exception
	ret_from_intr
	check_userspace
	restore_all
	restore_all_notrace
	restore_nocheck
	irq_return

And also, I found some interrupt/exception entry points that
cause similar problems.

This patch moves those symbols (including their container functions)
to .kprobes.text section to prevent any kprobes probing.

Signed-off-by: default avatarMasami Hiramatsu <mhiramat@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
LKML-Reference: <20090908164755.24050.81182.stgit@dhcp-100-2-132.bos.redhat.com>
Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
parent f12b4f54

arch/x86/kernel/entry_32.S

+24 −0
Original line number Diff line number Diff line
@@ -333,6 +333,10 @@ ENTRY(ret_from_fork) 
	CFI_ENDPROC

END(ret_from_fork)



/*

 * Interrupt exit functions should be protected against kprobes

 */

	.pushsection .kprobes.text, "ax"

/*

 * Return to user mode is not as complex as all this looks,

 * but we want the default path for a system call return to
@@ -383,6 +387,10 @@ need_resched: 
END(resume_kernel)

#endif

	CFI_ENDPROC

/*

 * End of kprobes section

 */

	.popsection



/* SYSENTER_RETURN points to after the "sysenter" instruction in

   the vsyscall page.  See vsyscall-sysentry.S, which defines the symbol.  */
@@ -513,6 +521,10 @@ sysexit_audit: 
	PTGS_TO_GS_EX

ENDPROC(ia32_sysenter_target)



/*

 * syscall stub including irq exit should be protected against kprobes

 */

	.pushsection .kprobes.text, "ax"

	# system call handler stub

ENTRY(system_call)

	RING0_INT_FRAME			# can't unwind into user space anyway
@@ -705,6 +717,10 @@ syscall_badsys: 
	jmp resume_userspace

END(syscall_badsys)

	CFI_ENDPROC

/*

 * End of kprobes section

 */

	.popsection



/*

 * System calls that need a pt_regs pointer.
@@ -814,6 +830,10 @@ common_interrupt: 
ENDPROC(common_interrupt)

	CFI_ENDPROC



/*

 *  Irq entries should be protected against kprobes

 */

	.pushsection .kprobes.text, "ax"

#define BUILD_INTERRUPT3(name, nr, fn)	\

ENTRY(name)				\

	RING0_INT_FRAME;		\
@@ -980,6 +1000,10 @@ ENTRY(spurious_interrupt_bug) 
	jmp error_code

	CFI_ENDPROC

END(spurious_interrupt_bug)

/*

 * End of kprobes section

 */

	.popsection



ENTRY(kernel_thread_helper)

	pushl $0		# fake return address for unwinder

kernel/kprobes.c

+2 −0
Original line number Diff line number Diff line
@@ -91,6 +91,8 @@ static spinlock_t *kretprobe_table_lock_ptr(unsigned long hash) 
static struct kprobe_blackpoint kprobe_blacklist[] = {

	{"preempt_schedule",},

	{"native_get_debugreg",},

	{"irq_entries_start",},

	{"common_interrupt",},

	{NULL}    /* Terminator */

};