[PATCH v1 net 06/15] bpf: Fix data-races around bpf_jit_kallsyms.

[Kuniyuki Iwashima]

While reading bpf_jit_kallsyms, it can be changed concurrently.
Thus, we need to add READ_ONCE() to its readers.

Fixes: 74451e66d516 ("bpf: make jited programs visible in traces")
Signed-off-by: Kuniyuki Iwashima <kuniyu@xxxxxxxxxx>
---
CC: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
---
 include/linux/filter.h | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/include/linux/filter.h b/include/linux/filter.h
index 09566ad211bd..35881fccce05 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -1110,14 +1110,16 @@ static inline bool bpf_jit_blinding_enabled(struct bpf_prog *prog)
 
 static inline bool bpf_jit_kallsyms_enabled(void)
 {
+	int jit_kallsyms = READ_ONCE(bpf_jit_kallsyms);
+
 	/* There are a couple of corner cases where kallsyms should
 	 * not be enabled f.e. on hardening.
 	 */
 	if (READ_ONCE(bpf_jit_harden))
 		return false;
-	if (!bpf_jit_kallsyms)
+	if (!jit_kallsyms)
 		return false;
-	if (bpf_jit_kallsyms == 1)
+	if (jit_kallsyms == 1)
 		return true;
 
 	return false;
-- 
2.30.2