Hello, On Tue, Oct 01, 2013 at 10:35:20PM +0200, Helge Deller wrote: > print_worker_info() includes no validity check on the pwq and wq > pointers before handing them over to the probe_kernel_read() functions. > > It seems that most architectures don't care about that, but at least on > the parisc architecture this leads to a kernel crash since accesses to > page zero are protected by the kernel for security reasons. > > Fix this problem by verifying the contents of pwq and wq before usage. > Even if probe_kernel_read() usually prevents such crashes by disabling > page faults, clean code should always include such checks. > > Without this fix issuing "echo t > /proc/sysrq-trigger" will immediately > crash the Linux kernel on the parisc architecture. Hmm... um had similar problem but the root cause here is that the arch isn't implementing probe_kernel_read() properly. We really have no idea what the pointer value may be at the dump point and that's why we use probe_kernel_read(). If something like the above is necessary for the time being, the correct place would be the arch probe_kernel_read() implementation. James, would it be difficult implement proper probe_kernel_read() on parisc? Thanks. -- tejun -- To unsubscribe from this list: send the line "unsubscribe linux-parisc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
