bpf, x86: set header->size properly before freeing it

On do_jit failure path, the header is freed by bpf_jit_binary_pack_free.
While bpf_jit_binary_pack_free doesn't require proper ro_header->size,
bpf_prog_pack_free still uses it. Set header->size in bpf_int_jit_compile
before calling bpf_jit_binary_pack_free.

Fixes: 1022a54 ("bpf, x86_64: Use bpf_jit_binary_pack_alloc")
Fixes: 33c9805 ("bpf: Introduce bpf_jit_binary_pack_[alloc|finalize|free]")
Reported-by: Kui-Feng Lee <kuifeng@fb.com>
Acked-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Song Liu <song@kernel.org>

Author: liu-song-6

arch/x86/net/bpf_jit_comp.c

@@ -2330,8 +2330,11 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog)
 		if (proglen <= 0) {
 out_image:
 			image = NULL;
-			if (header)
+			if (header) {
+				bpf_arch_text_copy(&header->size, &rw_header->size,
+						   sizeof(rw_header->size));
 				bpf_jit_binary_pack_free(header, rw_header);
+			}
 			prog = orig_prog;
 			goto out_addrs;
 		}

kernel/bpf/core.c

@@ -1112,13 +1112,16 @@ int bpf_jit_binary_pack_finalize(struct bpf_prog *prog,
  *   1) when the program is freed after;
  *   2) when the JIT engine fails (before bpf_jit_binary_pack_finalize).
  * For case 2), we need to free both the RO memory and the RW buffer.
- * Also, ro_header->size in 2) is not properly set yet, so rw_header->size
- * is used for uncharge.
+ *
+ * bpf_jit_binary_pack_free requires proper ro_header->size. However,
+ * bpf_jit_binary_pack_alloc does not set it. Therefore, ro_header->size
+ * must be set with either bpf_jit_binary_pack_finalize (normal path) or
+ * bpf_arch_text_copy (when jit fails).
  */
 void bpf_jit_binary_pack_free(struct bpf_binary_header *ro_header,
 			      struct bpf_binary_header *rw_header)
 {
-	u32 size = rw_header ? rw_header->size : ro_header->size;
+	u32 size = ro_header->size;
 
 	bpf_prog_pack_free(ro_header);
 	kvfree(rw_header);