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Kernel: Don't crash in page_fault_handler if current_thread is null

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If we are attempting to emit debugging information about an unhandleable
page fault, don't crash trying to kill threads or dump processes if the
current_thread isn't set in TLS. Attempt to keep proceeding in order to
dump as much useful information as possible.

Related: #6948
This commit is contained in:
Brian Gianforcaro 2021-05-14 22:33:18 -07:00 • committed by Andreas Kling
parent 00498e0405
commit db78331741
1 changed files with 13 additions and 11 deletions
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4
Kernel/Arch/i386/CPU.cpp
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@ -276,7 +276,7 @@ void page_fault_handler(TrapFrame* trap)
return; return;
} }
if (response != PageFaultResponse::OutOfMemory) { if (response != PageFaultResponse::OutOfMemory && current_thread) {
if (current_thread->has_signal_handler(SIGSEGV)) { if (current_thread->has_signal_handler(SIGSEGV)) {
current_thread->send_urgent_signal_to_self(SIGSEGV); current_thread->send_urgent_signal_to_self(SIGSEGV);
return; return;
@ -310,6 +310,7 @@ void page_fault_handler(TrapFrame* trap)
dbgln("Note: Address {} looks like a possible nullptr dereference", VirtualAddress(fault_address)); dbgln("Note: Address {} looks like a possible nullptr dereference", VirtualAddress(fault_address));
} }
if (current_thread) {
auto& current_process = current_thread->process(); auto& current_process = current_thread->process();
if (current_process.is_user_process()) { if (current_process.is_user_process()) {
current_process.set_coredump_metadata("fault_address", String::formatted("{:p}", fault_address)); current_process.set_coredump_metadata("fault_address", String::formatted("{:p}", fault_address));
@ -321,6 +322,7 @@ void page_fault_handler(TrapFrame* trap)
fault_access = fault.access() == PageFault::Access::Read ? "Read" : "Write"; fault_access = fault.access() == PageFault::Access::Read ? "Read" : "Write";
current_process.set_coredump_metadata("fault_access", fault_access); current_process.set_coredump_metadata("fault_access", fault_access);
} }
}
handle_crash(regs, "Page Fault", SIGSEGV, response == PageFaultResponse::OutOfMemory); handle_crash(regs, "Page Fault", SIGSEGV, response == PageFaultResponse::OutOfMemory);
} else if (response == PageFaultResponse::Continue) { } else if (response == PageFaultResponse::Continue) {