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-rw-r--r--net/ipv4/route.c10
1 files changed, 8 insertions, 2 deletions
diff --git a/net/ipv4/route.c b/net/ipv4/route.c
index a1f2830d8110..b5b47a26d4ec 100644
--- a/net/ipv4/route.c
+++ b/net/ipv4/route.c
@@ -476,12 +476,18 @@ u32 ip_idents_reserve(u32 hash, int segs)
atomic_t *p_id = ip_idents + hash % IP_IDENTS_SZ;
u32 old = ACCESS_ONCE(*p_tstamp);
u32 now = (u32)jiffies;
- u32 delta = 0;
+ u32 new, delta = 0;
if (old != now && cmpxchg(p_tstamp, old, now) == old)
delta = prandom_u32_max(now - old);
- return atomic_add_return(segs + delta, p_id) - segs;
+ /* Do not use atomic_add_return() as it makes UBSAN unhappy */
+ do {
+ old = (u32)atomic_read(p_id);
+ new = old + delta + segs;
+ } while (atomic_cmpxchg(p_id, old, new) != old);
+
+ return new - segs;
}
EXPORT_SYMBOL(ip_idents_reserve);