path: root/arch/parisc/lib/memcpy.c
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authorHelge Deller <deller@gmx.de>2013-10-01 21:54:46 +0200
committerHelge Deller <deller@gmx.de>2013-10-13 17:45:20 +0200
commit59b33f148cc08fb33cbe823fca1e34f7f023765e (patch)
tree798e64224feb4399d669e5deb6fb650710b6a2d9 /arch/parisc/lib/memcpy.c
parentparisc: mark parisc_terminate() noreturn and cold. (diff)
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>
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