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    Subject[PATCH 3.17 35/73] x86/asm/traps: Disable tracing and kprobes in fixup_bad_iret and sync_regs
    Date
    3.17-stable review patch.  If anyone has any objections, please let me know.

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

    From: Andy Lutomirski <luto@amacapital.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@amacapital.net>
    Cc: Linus Torvalds <torvalds@linux-foundation.org>
    Cc: Steven Rostedt <rostedt@goodmis.org>
    Link: http://lkml.kernel.org/r/50e33d26adca60816f3ba968875801652507d0c4.1416870125.git.luto@amacapital.net
    Signed-off-by: Ingo Molnar <mingo@kernel.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    arch/x86/kernel/traps.c | 5 +++--
    1 file changed, 3 insertions(+), 2 deletions(-)

    --- 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(st
    BUG_ON(!user_mode_vm(&new_stack->regs));
    return new_stack;
    }
    +NOKPROBE_SYMBOL(fixup_bad_iret);
    #endif

    /*



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