[PATCH] bpf: do not inline bpf_get_smp_processor_id() with CONFIG_SMP disabled

[Andrea Righi]

Calling bpf_get_smp_processor_id() in a kernel with CONFIG_SMP disabled
can trigger the following bug, as pcpu_hot is unavailable:

[    8.471774] BUG: unable to handle page fault for address: 00000000936a290c
[    8.471849] #PF: supervisor read access in kernel mode
[    8.471881] #PF: error_code(0x0000) - not-present page

Fix by preventing the inlining of bpf_get_smp_processor_id() when
CONFIG_SMP disabled.

Fixes: 1ae6921009e5 ("bpf: inline bpf_get_smp_processor_id() helper")
Signed-off-by: Andrea Righi <arighi@xxxxxxxxxx>
---
 kernel/bpf/verifier.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index f7f892a52a37..d85413f1a784 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -21272,7 +21272,7 @@ static int do_misc_fixups(struct bpf_verifier_env *env)
 			goto next_insn;
 		}
 
-#if defined(CONFIG_X86_64) && !defined(CONFIG_UML)
+#if defined(CONFIG_SMP) && defined(CONFIG_X86_64) && !defined(CONFIG_UML)
 		/* Implement bpf_get_smp_processor_id() inline. */
 		if (insn->imm == BPF_FUNC_get_smp_processor_id &&
 		    verifier_inlines_helper_call(env, insn->imm)) {
-- 
2.47.1