From: Masami Hiramatsu (Google) <[email protected]>
In __set_print_fmt(), LEN_OR_ZERO is defined as (len ? len - pos : 0).
If len is non-zero but smaller than pos, len - pos evaluates to a negative
integer. When passed as a size argument to snprintf(), this negative value
is cast to a large unsigned size_t, bypassing buffer size limits.
Ensure len > pos before subtracting to avoid integer underflow.
Fixes: 5bf652aaf46c ("tracing/probes: Integrate duplicate set_print_fmt()")
Cc: [email protected]
Assisted-by: Antigravity:gemini-3.5-flash
Signed-off-by: Masami Hiramatsu (Google) <[email protected]>
---
kernel/trace/trace_probe.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/trace/trace_probe.c b/kernel/trace/trace_probe.c
index 49daa3cc2a45..506e6037e163 100644
--- a/kernel/trace/trace_probe.c
+++ b/kernel/trace/trace_probe.c
@@ -2013,7 +2013,7 @@ int traceprobe_update_arg(struct probe_arg *arg)
}
/* When len=0, we just calculate the needed length */
-#define LEN_OR_ZERO (len ? len - pos : 0)
+#define LEN_OR_ZERO (len > pos ? len - pos : 0)
static int __set_print_fmt(struct trace_probe *tp, char *buf, int len,
enum probe_print_type ptype)
{
