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powerpc/mm/numa: skip NUMA_NO_NODE onlining in parse_numa_properties()
Executing node_set_online() when nid = NUMA_NO_NODE results in an undefined behavior. node_set_online() will call node_set_state(), into __node_set(), into set_bit(), and since NUMA_NO_NODE is -1 we'll end up doing a negative shift operation inside arch/powerpc/include/asm/bitops.h. This potential UB was detected running a kernel with CONFIG_UBSAN. The behavior was introduced by commit10f78fd0da
("powerpc/numa: Fix a regression on memoryless node 0"), where the check for nid > 0 was removed to fix a problem that was happening with nid = 0, but the result is that now we're trying to online NUMA_NO_NODE nids as well. Checking for nid >= 0 will allow node 0 to be onlined while avoiding this UB with NUMA_NO_NODE. Fixes:10f78fd0da
("powerpc/numa: Fix a regression on memoryless node 0") Reported-by: Ping Fang <pifang@redhat.com> Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20220224182312.1012527-1-danielhb413@gmail.com
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@ -956,7 +956,9 @@ static int __init parse_numa_properties(void)
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of_node_put(cpu);
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}
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node_set_online(nid);
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/* node_set_online() is an UB if 'nid' is negative */
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if (likely(nid >= 0))
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node_set_online(nid);
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}
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get_n_mem_cells(&n_mem_addr_cells, &n_mem_size_cells);
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