Reading other running task's stack can be a dangerous endeavor. Kasan
stack memory access instrumentation includes special prologue and epilogue
to mark/remove red zones in shadow memory between stack variables. For
that reason there is always a race between a task reading value in other
task's stack and that other task returning from a function and entering
another one generating different red zones pattern.
To avoid kasan reports simply perform uninstrumented memory reads.
Acked-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
goto out;
}
for (count = 0; count < 16; count++) {
- sf = (struct stack_frame *) sf->back_chain;
+ sf = (struct stack_frame *)READ_ONCE_NOCHECK(sf->back_chain);
if (sf <= low || sf > high) {
return_address = 0;
goto out;
}
- return_address = sf->gprs[8];
+ return_address = READ_ONCE_NOCHECK(sf->gprs[8]);
if (!in_sched_functions(return_address))
goto out;
}