netdev - [PATCH bpf-next 2/2] bpf, x86: set header->size properly before freeing it

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Date:   Tue, 1 Mar 2022 16:43:39 -0800
From:   Song Liu <song@...nel.org>
To:     <bpf@...r.kernel.org>, <netdev@...r.kernel.org>
CC:     <ast@...nel.org>, <daniel@...earbox.net>, <andrii@...nel.org>,
        <kernel-team@...com>, Song Liu <song@...nel.org>,
        Kui-Feng Lee <kuifeng@...com>
Subject: [PATCH bpf-next 2/2] 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@...com>
Signed-off-by: Song Liu <song@...nel.org>
---
 arch/x86/net/bpf_jit_comp.c | 6 +++++-
 kernel/bpf/core.c           | 7 ++++---
 2 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c
index c7db0fe4de2f..b923d81ff6f9 100644
--- a/arch/x86/net/bpf_jit_comp.c
+++ b/arch/x86/net/bpf_jit_comp.c
@@ -2330,8 +2330,12 @@ struct bpf_prog *bpf_int_jit_compile(struct bpf_prog *prog)
 		if (proglen <= 0) {
 out_image:
 			image = NULL;
-			if (header)
+			if (header) {
+				/* set header->size for bpf_arch_text_copy */
+				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 ebb0193d07f0..da587e4619e0 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -1112,13 +1112,14 @@ 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.
+ *
+ * If bpf_jit_binary_pack_free is called before _finalize (jit error),
+ * it is necessary to set ro_header->size properly before freeing it.
  */
 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);
-- 
2.30.2