2.6.36-stable review patch. If anyone has any objections, please let us know.
------------------ From: Frederic Weisbecker <[email protected]> commit 6c0aca288e726405b01dacb12cac556454d34b2a upstream. When a single step exception fires, the trap bits, used to signal hardware breakpoints, are in a random state. These trap bits might be set if another exception will follow, like a breakpoint in the next instruction, or a watchpoint in the previous one. Or there can be any junk there. So if we handle these trap bits during the single step exception, we are going to handle an exception twice, or we are going to handle junk. Just ignore them in this case. This fixes https://bugzilla.kernel.org/show_bug.cgi?id=21332 Reported-by: Michael Stefaniuc <[email protected]> Signed-off-by: Frederic Weisbecker <[email protected]> Cc: Rafael J. Wysocki <[email protected]> Cc: Maciej Rutecki <[email protected]> Cc: Alexandre Julliard <[email protected]> Cc: Jason Wessel <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- arch/x86/kernel/hw_breakpoint.c | 4 ++++ 1 file changed, 4 insertions(+) --- a/arch/x86/kernel/hw_breakpoint.c +++ b/arch/x86/kernel/hw_breakpoint.c @@ -433,6 +433,10 @@ static int __kprobes hw_breakpoint_handl dr6_p = (unsigned long *)ERR_PTR(args->err); dr6 = *dr6_p; + /* If it's a single step, TRAP bits are random */ + if (dr6 & DR_STEP) + return NOTIFY_DONE; + /* Do an early return if no trap bits are set in DR6 */ if ((dr6 & DR_TRAP_BITS) == 0) return NOTIFY_DONE; _______________________________________________ stable mailing list [email protected] http://linux.kernel.org/mailman/listinfo/stable
