Thread (5 messages) flat view 5 messages, 5 authors, 2021-03-14

Re: [PATCH net] flow_dissector: fix byteorder of dissected ICMP ID

From: Jakub Sitnicki <jakub@cloudflare.com>
Date: 2021-03-14 20:22:39
Also in: lkml

On Fri, Mar 12, 2021 at 09:08 PM CET, Alexander Lobakin wrote:
quoted hunk ↗ jump to hunk
flow_dissector_key_icmp::id is of type u16 (CPU byteorder),
ICMP header has its ID field in network byteorder obviously.
Sparse says:

net/core/flow_dissector.c:178:43: warning: restricted __be16 degrades to integer

Convert ID value to CPU byteorder when storing it into
flow_dissector_key_icmp.

Fixes: 5dec597e5cd0 ("flow_dissector: extract more ICMP information")
Signed-off-by: Alexander Lobakin <redacted>
---
 net/core/flow_dissector.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c
index 2ef2224b3bff..a96a4f5de0ce 100644
--- a/net/core/flow_dissector.c
+++ b/net/core/flow_dissector.c
@@ -176,7 +176,7 @@ void skb_flow_get_icmp_tci(const struct sk_buff *skb,
 	 * avoid confusion with packets without such field
 	 */
 	if (icmp_has_id(ih->type))
-		key_icmp->id = ih->un.echo.id ? : 1;
+		key_icmp->id = ih->un.echo.id ? ntohs(ih->un.echo.id) : 1;
 	else
 		key_icmp->id = 0;
 }
Smells like a breaking change for existing consumers of this value.

How about we change the type of flow_dissector_key_icmp{}.id to __be16
instead to make sparse happy?
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