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| author | Eric Dumazet <edumazet@google.com> | 2026-03-02 19:39:33 +0300 |
|---|---|---|
| committer | Jakub Kicinski <kuba@kernel.org> | 2026-03-05 03:51:10 +0300 |
| commit | c26b8c4e291c55c7b2138d7bcb27348ca3a5ae59 (patch) | |
| tree | db9a44805f438b49c9272ef9e93e1f665396a375 /include | |
| parent | 98d95000bb1207f86a0e5876755ac2308ac86d2d (diff) | |
| download | linux-c26b8c4e291c55c7b2138d7bcb27348ca3a5ae59.tar.xz | |
net: fix off-by-one in udp_flow_src_port() / psp_write_headers()
udp_flow_src_port() and psp_write_headers() use ip_local_port_range.
ip_local_port_range is inclusive : all ports between min and max
can be used.
Before this patch, if ip_local_port_range was set to 40000-40001
40001 would not be used as a source port.
Use reciprocal_scale() to help code readability.
Not tagged for stable trees, as this change could break user
expectations.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://patch.msgid.link/20260302163933.1754393-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/net/udp.h | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/include/net/udp.h b/include/net/udp.h index da68702ddf6e..b648003e5792 100644 --- a/include/net/udp.h +++ b/include/net/udp.h @@ -29,6 +29,7 @@ #include <linux/seq_file.h> #include <linux/poll.h> #include <linux/indirect_call_wrapper.h> +#include <linux/math.h> /** * struct udp_skb_cb - UDP(-Lite) private variables @@ -376,7 +377,7 @@ static inline __be16 udp_flow_src_port(struct net *net, struct sk_buff *skb, */ hash ^= hash << 16; - return htons((((u64) hash * (max - min)) >> 32) + min); + return htons(reciprocal_scale(hash, max - min + 1) + min); } static inline int udp_rqueue_get(struct sock *sk) |