Messages in this thread | ![/](/images/icornerl.gif) | | Date | Mon, 20 Nov 2023 19:15:58 +0800 | Subject | Re: [PATCH] net: sched: Fix an endian bug in tcf_proto_create | From | Kunwu Chan <> |
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Hi Simon,
Thanks for your reply. For a lot of newcomers who aren't proficient in this part of the code, like me, it might be confusing what is the correct endien and width of a protocol.
In response to your question, I wonder if it is necessary to implement a unified checking mechanism with a strict parameter validation for all invocation parameters?
For example, add an input parameter to the 'tcf_proto_create' to represent the endien and width of the protocol, and check the validity of the input parameter at the beginning of the function.
I don't have a good idea of how to make sure that the right type is used in the call path. This is just my personal opinion, welcome to discuss.
On 2023/11/20 18:04, Simon Horman wrote: > On Fri, Nov 17, 2023 at 09:06:45AM -0300, Pedro Tammela wrote: >> On 17/11/2023 06:31, Kunwu Chan wrote: >>> net/sched/cls_api.c:390:22: warning: incorrect type in assignment (different base types) >>> net/sched/cls_api.c:390:22: expected restricted __be16 [usertype] protocol >>> net/sched/cls_api.c:390:22: got unsigned int [usertype] protocol >>> >>> Fixes: 33a48927c193 ("sched: push TC filter protocol creation into a separate function") >>> >>> Signed-off-by: Kunwu Chan <chentao@kylinos.cn> >>> --- >>> net/sched/cls_api.c | 2 +- >>> 1 file changed, 1 insertion(+), 1 deletion(-) >>> >>> diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c >>> index 1976bd163986..f73f39f61f66 100644 >>> --- a/net/sched/cls_api.c >>> +++ b/net/sched/cls_api.c >>> @@ -387,7 +387,7 @@ static struct tcf_proto *tcf_proto_create(const char *kind, u32 protocol, >>> goto errout; >>> } >>> tp->classify = tp->ops->classify; >>> - tp->protocol = protocol; >>> + tp->protocol = cpu_to_be16(protocol); >>> tp->prio = prio; >>> tp->chain = chain; >>> spin_lock_init(&tp->lock); >> I don't believe there's something to fix here either > > Hi Pedro and Kunwu, > > I suspect that updating the byte order of protocol isn't correct > here - else I'd assume we would have seen a user-visible bug on > little-endian systems buy now. > > But nonetheless I think there is a problem, which is that the appropriate > types aren't being used, which means the tooling isn't helping us wrt any > bugs that might subsequently be added or already lurking. So I think an > appropriate question is, what is the endien and width of protocol, and how > can we use an appropriate type throughout the call-path?
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