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: 1022a5498f6f ("bpf, x86_64: Use bpf_jit_binary_pack_alloc")
Fixes: 33c9805860e5 ("bpf: Introduce bpf_jit_binary_pack_[alloc|finalize|free]")
Reported-by: Kui-Feng Lee <kuifeng@fb.com>
Signed-off-by: Song Liu <song@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20220302175126.247459-3-song@kernel.org

diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
index c7db0fe..e6ff8f4 100644 (file)
--- a/arch/x86/net/bpf_jit_comp.c
+++ b/arch/x86/net/bpf_jit_comp.c
@@ -2330,8 +2330,11 @@ skip_init_addrs:
                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;
                }

diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index ebb0193..ab630f7 100644 (file)
--- a/kernel/bpf/core.c
+++ b/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);