[PATCH iproute2] tc util: Fix possible buffer overflow when print class id

[Vadim Kochan]

From: Vadim Kochan <vadi...@gmail.com>

Use correct handle buffer length.

Signed-off-by: Vadim Kochan <vadi...@gmail.com>
---
 tc/tc_util.c | 19 ++++++++++---------
 1 file changed, 10 insertions(+), 9 deletions(-)

diff --git a/tc/tc_util.c b/tc/tc_util.c
index 1d3153d..dc2b70f 100644
--- a/tc/tc_util.c
+++ b/tc/tc_util.c
@@ -128,30 +128,31 @@ ok:
        return 0;
 }
 
-int print_tc_classid(char *buf, int len, __u32 h)
+int print_tc_classid(char *buf, int blen, __u32 h)
 {
-       char handle[40] = {};
+       SPRINT_BUF(handle) = {};
+       int hlen = SPRINT_BSIZE - 1;
 
        if (h == TC_H_ROOT)
                sprintf(handle, "root");
        else if (h == TC_H_UNSPEC)
-               snprintf(handle, len, "none");
+               snprintf(handle, hlen, "none");
        else if (TC_H_MAJ(h) == 0)
-               snprintf(handle, len, ":%x", TC_H_MIN(h));
+               snprintf(handle, hlen, ":%x", TC_H_MIN(h));
        else if (TC_H_MIN(h) == 0)
-               snprintf(handle, len, "%x:", TC_H_MAJ(h) >> 16);
+               snprintf(handle, hlen, "%x:", TC_H_MAJ(h) >> 16);
        else
-               snprintf(handle, len, "%x:%x", TC_H_MAJ(h) >> 16, TC_H_MIN(h));
+               snprintf(handle, hlen, "%x:%x", TC_H_MAJ(h) >> 16, TC_H_MIN(h));
 
        if (use_names) {
                char clname[IDNAME_MAX] = {};
 
                if (id_to_name(cls_names, h, clname))
-                       snprintf(buf, len, "%s#%s", clname, handle);
+                       snprintf(buf, blen, "%s#%s", clname, handle);
                else
-                       snprintf(buf, len, "%s", handle);
+                       snprintf(buf, blen, "%s", handle);
        } else {
-               snprintf(buf, len, "%s", handle);
+               snprintf(buf, blen, "%s", handle);
        }
 
        return 0;
-- 
2.3.1

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