m2sm() converts a u32 slope to a u64 scaled value. For large inputs (e.g. m1=4000000000), the result can reach 2^32. rtsc_min() stores the difference of two such u64 values in a u32 variable `dsm` and uses it as a divisor. When the difference is exactly 2^32 the truncation yields zero, causing a divide-by-zero oops in the concave-curve intersection path: Oops: divide error: 0000 RIP: 0010:rtsc_min (net/sched/sch_hfsc.c:601) Call Trace: init_ed (net/sched/sch_hfsc.c:629) hfsc_enqueue (net/sched/sch_hfsc.c:1569) [...] Widen `dsm` to u64 and replace do_div() with div64_u64() so the full difference is preserved. Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Reported-by: Weiming Shi Signed-off-by: Xiang Mei --- v2: resend to netdev ML net/sched/sch_hfsc.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/net/sched/sch_hfsc.c b/net/sched/sch_hfsc.c index b5657ffbbf84..83b2ca2e37fc 100644 --- a/net/sched/sch_hfsc.c +++ b/net/sched/sch_hfsc.c @@ -555,7 +555,7 @@ static void rtsc_min(struct runtime_sc *rtsc, struct internal_sc *isc, u64 x, u64 y) { u64 y1, y2, dx, dy; - u32 dsm; + u64 dsm; if (isc->sm1 <= isc->sm2) { /* service curve is convex */ @@ -598,7 +598,7 @@ rtsc_min(struct runtime_sc *rtsc, struct internal_sc *isc, u64 x, u64 y) */ dx = (y1 - y) << SM_SHIFT; dsm = isc->sm1 - isc->sm2; - do_div(dx, dsm); + dx = div64_u64(dx, dsm); /* * check if (x, y1) belongs to the 1st segment of rtsc. * if so, add the offset. -- 2.43.0