On Mon, 2015-01-05 at 12:49 -0800, gregkh@xxxxxxxxxxxxxxxxxxx wrote:
> The patch below does not apply to the 3.10-stable tree.
> If someone wants it applied there, or to any other stable or longterm
> tree, then please email the backport, including the original git commit
> id to <stable@xxxxxxxxxxxxxxx>.
I've attached what I think is a sensible backport.
Ben.
> thanks,
>
> greg k-h
>
> ------------------ original commit in Linus's tree ------------------
>
> From 7ddc6a2199f1da405a2fb68c40db8899b1a8cd87 Mon Sep 17 00:00:00 2001
> From: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
> Date: Mon, 24 Nov 2014 17:39:06 -0800
> Subject: [PATCH] x86/asm/traps: Disable tracing and kprobes in fixup_bad_iret
> and sync_regs
>
> 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@xxxxxxxxxxxxxx>
> Cc: <stable@xxxxxxxxxxxxxxx> # Backport as far back as it would apply
> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
> Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
> Link: http://lkml.kernel.org/r/50e33d26adca60816f3ba968875801652507d0c4.1416870125.git.luto@xxxxxxxxxxxxxx
> Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
>
> 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
>
> /*
--
Ben Hutchings
The world is coming to an end. Please log off.
From 0b740af1a1697796b5a9a0b024b22b7e97e9bfd2 Mon Sep 17 00:00:00 2001
From: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
Date: Mon, 24 Nov 2014 17:39:06 -0800
Subject: [PATCH] x86/asm/traps: Disable tracing and kprobes in fixup_bad_iret
and sync_regs
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@xxxxxxxxxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Link: http://lkml.kernel.org/r/50e33d26adca60816f3ba968875801652507d0c4.1416870125.git.luto@xxxxxxxxxxxxxx
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
[bwh: Backported to 3.10:
- Use __kprobes instead of NOKPROBE_SYMBOL()
- Adjust context]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
arch/x86/kernel/traps.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kernel/traps.c b/arch/x86/kernel/traps.c
index 332cafe..0010ed7 100644
--- a/arch/x86/kernel/traps.c
+++ b/arch/x86/kernel/traps.c
@@ -362,7 +362,7 @@ exit:
* for scheduling or signal handling. The actual stack switch is done in
* entry.S
*/
-asmlinkage __kprobes struct pt_regs *sync_regs(struct pt_regs *eregs)
+asmlinkage notrace __kprobes struct pt_regs *sync_regs(struct pt_regs *eregs)
{
struct pt_regs *regs = eregs;
/* Did already sync */
@@ -387,7 +387,7 @@ struct bad_iret_stack {
struct pt_regs regs;
};
-asmlinkage __visible
+asmlinkage __visible notrace __kprobes
struct bad_iret_stack *fixup_bad_iret(struct bad_iret_stack *s)
{
/*
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