1 files changed, 5 insertions, 3 deletions

diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index 08fcfe440c63..9864a35c8bb5 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -196,11 +196,13 @@ BPF_CALL_5(bpf_trace_printk, char *, fmt, u32, fmt_size, u64, arg1,
                         i++;
                 } else if (fmt[i] == 'p' || fmt[i] == 's') {
                         mod[fmt_cnt]++;
-                        i++;
-                        if (!isspace(fmt[i]) && !ispunct(fmt[i]) && fmt[i] != 0)
+                        /* disallow any further format extensions */
+                        if (fmt[i + 1] != 0 &&
+                            !isspace(fmt[i + 1]) &&
+                            !ispunct(fmt[i + 1]))
                                 return -EINVAL;
                         fmt_cnt++;
-                        if (fmt[i - 1] == 's') {
+                        if (fmt[i] == 's') {
                                 if (str_seen)
                                         /* allow only one '%s' per fmt string */
                                         return -EINVAL;