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authorJeff Dike <jdike@addtoit.com>2007-09-18 22:46:49 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-09-19 11:24:18 -0700
commit508a92741a105e2e3d466cd727fb73154ebf08de (patch)
tree4dabe8327cc47c2d26239d227d48fc83944e5ff1 /arch/um/include/kern_util.h
parent480eccf9ae1073b87bb4fe118971fbf134a5bc61 (diff)
downloadlinux-linaro-508a92741a105e2e3d466cd727fb73154ebf08de.tar.gz
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 <jdike@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch/um/include/kern_util.h')
-rw-r--r--arch/um/include/kern_util.h2
1 files changed, 1 insertions, 1 deletions
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