From 508a92741a105e2e3d466cd727fb73154ebf08de Mon Sep 17 00:00:00 2001 From: Jeff Dike Date: Tue, 18 Sep 2007 22:46:49 -0700 Subject: uml: fix irqstack crash This patch fixes a crash caused by an interrupt coming in when an IRQ stack is being torn down. When this happens, handle_signal will loop, setting up the IRQ stack again because the tearing down had finished, and handling whatever signals had come in. However, to_irq_stack returns a mask of pending signals to be handled, plus bit zero is set if the IRQ stack was already active, and thus shouldn't be torn down. This causes a problem because when handle_signal goes around the loop, sig will be zero, and to_irq_stack will duly set bit zero in the returned mask, faking handle_signal into believing that it shouldn't tear down the IRQ stack and return thread_info pointers back to their original values. This will eventually cause a crash, as the IRQ stack thread_info will continue pointing to the original task_struct and an interrupt will look into it after it has been freed. The fix is to stop passing a signal number into to_irq_stack. Rather, the pending signals mask is initialized beforehand with the bit for sig already set. References to sig in to_irq_stack can be replaced with references to the mask. [akpm@linux-foundation.org: use UL] Signed-off-by: Jeff Dike Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/um/include/kern_util.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch/um/include') diff --git a/arch/um/include/kern_util.h b/arch/um/include/kern_util.h index 8d7f7c1cb9c..6c2be26f1d7 100644 --- a/arch/um/include/kern_util.h +++ b/arch/um/include/kern_util.h @@ -117,7 +117,7 @@ extern void sigio_handler(int sig, union uml_pt_regs *regs); extern void copy_sc(union uml_pt_regs *regs, void *from); -unsigned long to_irq_stack(int sig, unsigned long *mask_out); +extern unsigned long to_irq_stack(unsigned long *mask_out); unsigned long from_irq_stack(int nested); #endif -- cgit v1.2.3-70-g09d2