bpf: turn off sanitizer in do_misc_fixups for old clang

clang versions before version 18 manage to badly optimize the bpf
verifier, with lots of variable spills leading to excessive stack
usage in addition to likely rather slow code:

kernel/bpf/verifier.c:23936:5: error: stack frame size (2096) exceeds limit (1280) in 'bpf_check' [-Werror,-Wframe-larger-than]
kernel/bpf/verifier.c:21563:12: error: stack frame size (1984) exceeds limit (1280) in 'do_misc_fixups' [-Werror,-Wframe-larger-than]

Turn off the sanitizer in the two functions that suffer the most from
this when using one of the affected clang version.

Signed-off-by: Arnd Bergmann <[email protected]>

Author: arndb

kernel/bpf/verifier.c

@@ -19811,7 +19811,14 @@ static int do_check_insn(struct bpf_verifier_env *env, bool *do_print_state)
 	return 0;
 }
 
-static int do_check(struct bpf_verifier_env *env)
+#if defined(CONFIG_CC_IS_CLANG) && CONFIG_CLANG_VERSION < 180100
+/* old clang versions cause excessive stack usage here */
+#define __workaround_kasan  __disable_sanitizer_instrumentation
+#else
+#define __workaround_kasan
+#endif
+
+static __workaround_kasan int do_check(struct bpf_verifier_env *env)
 {
 	bool pop_log = !(env->log.level & BPF_LOG_LEVEL2);
 	struct bpf_verifier_state *state = env->cur_state;
@@ -21818,7 +21825,7 @@ static int add_hidden_subprog(struct bpf_verifier_env *env, struct bpf_insn *pat
 /* Do various post-verification rewrites in a single program pass.
  * These rewrites simplify JIT and interpreter implementations.
  */
-static int do_misc_fixups(struct bpf_verifier_env *env)
+static __workaround_kasan int do_misc_fixups(struct bpf_verifier_env *env)
 {
 	struct bpf_prog *prog = env->prog;
 	enum bpf_attach_type eatype = prog->expected_attach_type;