diff options
author | Jeff Dike <jdike@addtoit.com> | 2007-09-19 07:46:49 +0200 |
---|---|---|
committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2007-09-19 20:24:18 +0200 |
commit | 508a92741a105e2e3d466cd727fb73154ebf08de (patch) | |
tree | 4dabe8327cc47c2d26239d227d48fc83944e5ff1 /arch/um/os-Linux/signal.c | |
parent | Fix NUMA Memory Policy Reference Counting (diff) | |
download | linux-508a92741a105e2e3d466cd727fb73154ebf08de.tar.xz linux-508a92741a105e2e3d466cd727fb73154ebf08de.zip |
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 '')
-rw-r--r-- | arch/um/os-Linux/signal.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/arch/um/os-Linux/signal.c b/arch/um/os-Linux/signal.c index 18e5c8b67eb8..b98f7ea2d2f6 100644 --- a/arch/um/os-Linux/signal.c +++ b/arch/um/os-Linux/signal.c @@ -119,7 +119,7 @@ void (*handlers[_NSIG])(int sig, struct sigcontext *sc); void handle_signal(int sig, struct sigcontext *sc) { - unsigned long pending = 0; + unsigned long pending = 1UL << sig; do { int nested, bail; @@ -134,7 +134,7 @@ void handle_signal(int sig, struct sigcontext *sc) * have to return, and the upper handler will deal * with this interrupt. */ - bail = to_irq_stack(sig, &pending); + bail = to_irq_stack(&pending); if(bail) return; |