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Fixed possible NULL dereference in vm_page_fault. 

This bug was introduced by changing IS_USER_ADDRESS to check against
USER_BASE AND USER_TOP rather than just !IS_KERNEL_ADDRESS. Faults
on addresses outside both the user and kernel address spaces (i.e. the
gap between user and kernel) would result in addressSpace being NULL,
but addressSpace was being used without checking for NULL at one point.
This commit is contained in:
Alex Smith 2012-08-14 17:46:09 +01:00
parent a53cfbf491
commit 4efc3430a0
1 changed files with 7 additions and 4 deletions
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11
src/system/kernel/vm/vm.cpp
View File

@ -4058,11 +4058,13 @@ vm_page_fault(addr_t address, addr_t faultAddress, bool isWrite, bool isUser,
}
} else {
#if 1
addressSpace->ReadLock();
// TODO: remove me once we have proper userland debugging support
// (and tools)
VMArea* area = addressSpace->LookupArea(faultAddress);
VMArea* area = NULL;
if (addressSpace != NULL) {
addressSpace->ReadLock();
area = addressSpace->LookupArea(faultAddress);
}
Thread* thread = thread_get_current_thread();
dprintf("vm_page_fault: thread \"%s\" (%" B_PRId32 ") in team "
@ -4127,7 +4129,8 @@ vm_page_fault(addr_t address, addr_t faultAddress, bool isWrite, bool isUser,
}
# endif // 0 (stack trace)
addressSpace->ReadUnlock();
if (addressSpace != NULL)
addressSpace->ReadUnlock();
#endif
// If the thread has a signal handler for SIGSEGV, we simply