Stack validation in early boot can just bail out of checking alternate
stacks if they are not validated yet. Checking against a NULL stack
could cause NULLish pointer values to be considered valid.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20221216115930.2667772-5-npiggin@gmail.com
unsigned long stack_page;
unsigned long cpu = task_cpu(p);
+ if (!hardirq_ctx[cpu] || !softirq_ctx[cpu])
+ return 0;
+
stack_page = (unsigned long)hardirq_ctx[cpu];
if (sp >= stack_page && sp <= stack_page + THREAD_SIZE - nbytes)
return 1;
if (!paca_ptrs)
return 0;
+ if (!paca_ptrs[cpu]->emergency_sp)
+ return 0;
+
+# ifdef CONFIG_PPC_BOOK3S_64
+ if (!paca_ptrs[cpu]->nmi_emergency_sp || !paca_ptrs[cpu]->mc_emergency_sp)
+ return 0;
+#endif
+
stack_page = (unsigned long)paca_ptrs[cpu]->emergency_sp - THREAD_SIZE;
if (sp >= stack_page && sp <= stack_page + THREAD_SIZE - nbytes)
return 1;