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author | Helge Deller <deller@gmx.de> | 2013-10-01 21:54:46 +0200 |
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committer | Helge Deller <deller@gmx.de> | 2013-10-13 17:45:20 +0200 |
commit | 59b33f148cc08fb33cbe823fca1e34f7f023765e (patch) | |
tree | 798e64224feb4399d669e5deb6fb650710b6a2d9 | |
parent | a60ac4b5f0b630889a01293db52ac65003a01e98 (diff) | |
download | op-kernel-dev-59b33f148cc08fb33cbe823fca1e34f7f023765e.zip op-kernel-dev-59b33f148cc08fb33cbe823fca1e34f7f023765e.tar.gz |
parisc: fix interruption handler to respect pagefault_disable()
Running an "echo t > /proc/sysrq-trigger" crashes the parisc kernel. The
problem is, that in print_worker_info() we try to read the workqueue info via
the probe_kernel_read() functions which use pagefault_disable() to avoid
crashes like this:
probe_kernel_read(&pwq, &worker->current_pwq, sizeof(pwq));
probe_kernel_read(&wq, &pwq->wq, sizeof(wq));
probe_kernel_read(name, wq->name, sizeof(name) - 1);
The problem here is, that the first probe_kernel_read(&pwq) might return zero
in pwq and as such the following probe_kernel_reads() try to access contents of
the page zero which is read protected and generate a kernel segfault.
With this patch we fix the interruption handler to call parisc_terminate()
directly only if pagefault_disable() was not called (in which case
preempt_count()==0). Otherwise we hand over to the pagefault handler which
will try to look up the faulting address in the fixup tables.
Signed-off-by: Helge Deller <deller@gmx.de>
Cc: <stable@vger.kernel.org> # v3.0+
Signed-off-by: John David Anglin <dave.anglin@bell.net>
Signed-off-by: Helge Deller <deller@gmx.de>
-rw-r--r-- | arch/parisc/kernel/traps.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/arch/parisc/kernel/traps.c b/arch/parisc/kernel/traps.c index ebc877c..1cd1d0c 100644 --- a/arch/parisc/kernel/traps.c +++ b/arch/parisc/kernel/traps.c @@ -800,14 +800,14 @@ void notrace handle_interruption(int code, struct pt_regs *regs) else { /* - * The kernel should never fault on its own address space. + * The kernel should never fault on its own address space, + * unless pagefault_disable() was called before. */ - if (fault_space == 0) + if (fault_space == 0 && !in_atomic()) { pdc_chassis_send_status(PDC_CHASSIS_DIRECT_PANIC); parisc_terminate("Kernel Fault", regs, code, fault_address); - } } |