On Thu, 2025-01-16 at 08:49 +0000, Gavrilov Ilia wrote:
Since the new_metric and last_hop_metric variables can reach the MAX_METRIC(0xffffffff) value, an integer overflow may occur when multiplying them by 10/9. It can lead to incorrect behavior.
Found by InfoTeCS on behalf of Linux Verification Center (linuxtesting.org) with SVACE.
Fixes: a8d418d9ac25 ("mac80211: mesh: only switch path when new metric is at least 10% better") Cc: stable@vger.kernel.org
Seems a bit overblown for stable, but also don't really care...
+static inline bool is_metric_better(u32 x, u32 y, u32 percent) +{
You shouldn't put inline here, in general.
Also that function probably wants a comment, and the 'percent' argument is hardcoded to 10, so you don't need it. Let's keep this stuff simple, *especially* if it's for stable too ...
- if (check_add_overflow(x, a, &e)) {
if (x > y - a)return false;
seems simpler as "return x > y - a;" or so?
johannes