BPF_LOG_KERNEL is only used internally, so disallow bpf_btf_load()
to set log level as BPF_LOG_KERNEL. The same checking has already
been done in bpf_check(), so factor out a helper to check the
validity of log attributes and use it in both places.

Fixes: 8580ac9404f6 ("bpf: Process in-kernel BTF")
Signed-off-by: Hou Tao <redacted>
Acked-by: Yonghong Song <redacted>
Acked-by: Martin KaFai Lau <redacted>
---
 include/linux/bpf_verifier.h | 7 +++++++
 kernel/bpf/btf.c             | 3 +--
 kernel/bpf/verifier.c        | 6 +++---
 3 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h
index c8a78e830fca..a3d17601a5a7 100644
--- a/include/linux/bpf_verifier.h
+++ b/include/linux/bpf_verifier.h

@@ -396,6 +396,13 @@ static inline bool bpf_verifier_log_needed(const struct bpf_verifier_log *log)
                 log->level == BPF_LOG_KERNEL);
 }

+static inline bool
+bpf_verifier_log_attr_valid(const struct bpf_verifier_log *log, u32 max_total)
+{
+       return log->len_total >= 128 && log->len_total <= max_total &&
+              log->level && log->ubuf && !(log->level & ~BPF_LOG_MASK);
+}
+
 #define BPF_MAX_SUBPROGS 256

 struct bpf_subprog_info {

diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index 6b9d23be1e99..308c345cd811 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c

@@ -4472,8 +4472,7 @@ static struct btf *btf_parse(bpfptr_t btf_data, u32 btf_data_size,
                log->len_total = log_size;

                /* log attributes have to be sane */
-               if (log->len_total < 128 || log->len_total > UINT_MAX >> 8 ||
-                   !log->level || !log->ubuf) {
+               if (!bpf_verifier_log_attr_valid(log, UINT_MAX >> 8)) {
                        err = -EINVAL;
                        goto errout;
                }

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 722aea00d44e..f128e6799cb5 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c

@@ -13969,11 +13969,11 @@ int bpf_check(struct bpf_prog **prog, union bpf_attr *attr, bpfptr_t uattr)
                log->ubuf = (char __user *) (unsigned long) attr->log_buf;
                log->len_total = attr->log_size;

-               ret = -EINVAL;
                /* log attributes have to be sane */
-               if (log->len_total < 128 || log->len_total > UINT_MAX >> 2 ||
-                   !log->level || !log->ubuf || log->level & ~BPF_LOG_MASK)
+               if (!bpf_verifier_log_attr_valid(log, UINT_MAX >> 2)) {
+                       ret = -EINVAL;