linux-kernel - [PATCH 3.16.y-ckt 165/168] x86/asm/traps: Disable tracing and kprobes in fixup_bad_iret and sync

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Message-Id: <1418653622-21105-166-git-send-email-luis.henriques@canonical.com>
Date:	Mon, 15 Dec 2014 14:26:59 +0000
From:	Luis Henriques <luis.henriques@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	Andy Lutomirski <luto@...capital.net>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Steven Rostedt <rostedt@...dmis.org>,
	Ingo Molnar <mingo@...nel.org>,
	Luis Henriques <luis.henriques@...onical.com>
Subject: [PATCH 3.16.y-ckt 165/168] x86/asm/traps: Disable tracing and kprobes in fixup_bad_iret and sync_regs

3.16.7-ckt3 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Andy Lutomirski <luto@...capital.net>

commit 7ddc6a2199f1da405a2fb68c40db8899b1a8cd87 upstream.

These functions can be executed on the int3 stack, so kprobes
are dangerous. Tracing is probably a bad idea, too.

Fixes: b645af2d5905 ("x86_64, traps: Rework bad_iret")
Signed-off-by: Andy Lutomirski <luto@...capital.net>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Steven Rostedt <rostedt@...dmis.org>
Link: http://lkml.kernel.org/r/50e33d26adca60816f3ba968875801652507d0c4.1416870125.git.luto@amacapital.net
Signed-off-by: Ingo Molnar <mingo@...nel.org>
Signed-off-by: Luis Henriques <luis.henriques@...onical.com>
---
 arch/x86/kernel/traps.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index de801f22128a..07ab8e9733c5 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -387,7 +387,7 @@ NOKPROBE_SYMBOL(do_int3);
  * for scheduling or signal handling. The actual stack switch is done in
  * entry.S
  */
-asmlinkage __visible struct pt_regs *sync_regs(struct pt_regs *eregs)
+asmlinkage __visible notrace struct pt_regs *sync_regs(struct pt_regs *eregs)
 {
 	struct pt_regs *regs = eregs;
 	/* Did already sync */
@@ -413,7 +413,7 @@ struct bad_iret_stack {
 	struct pt_regs regs;
 };
 
-asmlinkage __visible
+asmlinkage __visible notrace
 struct bad_iret_stack *fixup_bad_iret(struct bad_iret_stack *s)
 {
 	/*
@@ -436,6 +436,7 @@ struct bad_iret_stack *fixup_bad_iret(struct bad_iret_stack *s)
 	BUG_ON(!user_mode_vm(&new_stack->regs));
 	return new_stack;
 }
+NOKPROBE_SYMBOL(fixup_bad_iret);
 #endif
 
 /*
-- 
2.1.3

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