scmp_bpf_sim: fix aliasing UB

See seccomp#425. Punning sys_data_b between uint32_t* and struct* seccomp_data isn't legal, use memcpy to fix the testsuite with Clang 17. Modern compilers recognise this idiom and optimise it out anyway. Signed-off-by: Sam James <[email protected]> Acked-by: Tom Hromatka <[email protected]> Signed-off-by: Paul Moore <[email protected]>
loongarch64 · Sep 5, 2024 · 2847f10 · 2847f10
1 parent 5eb0b07
commit 2847f10
Showing 1 changed file with 2 additions and 1 deletion.
diff --git a/tools/scmp_bpf_sim.c b/tools/scmp_bpf_sim.c
@@ -182,7 +182,8 @@ static void bpf_execute(const struct bpf_program *prg,
 		switch (code) {
 		case BPF_LD+BPF_W+BPF_ABS:
 			if (k < BPF_SYSCALL_MAX) {
-				uint32_t val = *((uint32_t *)&sys_data_b[k]);
+				uint32_t val;
+				memcpy(&val, &sys_data_b[k], sizeof(val));
 				state.acc = ttoh32(arch, val);
 			} else
 				exit_error(ERANGE, ip_c);