Commit 7a1ca972 authored Apr 02, 2020 by Jakub Sitnicki Committed by Daniel Borkmann Apr 03, 2020

net, sk_msg: Don't use RCU_INIT_POINTER on sk_user_data



sparse reports an error due to use of RCU_INIT_POINTER helper to assign to
sk_user_data pointer, which is not tagged with __rcu:

net/core/sock.c:1875:25: error: incompatible types in comparison expression (different address spaces):
net/core/sock.c:1875:25:    void [noderef] <asn:4> *
net/core/sock.c:1875:25:    void *

... and rightfully so. sk_user_data is not always treated as a pointer to
an RCU-protected data. When it is used to point at an RCU-protected object,
we access it with __sk_user_data to inform sparse about it.

In this case, when the child socket does not inherit sk_user_data from the
parent, there is no reason to treat it as an RCU-protected pointer.

Use a regular assignment to clear the pointer value.

Fixes: f1ff5ce2 ("net, sk_msg: Clear sk_user_data pointer on clone if tagged")
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Jakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20200402125524.851439-1-jakub@cloudflare.com

parent 93bbb255

net/core/sock.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -1872,7 +1872,7 @@ struct sock sk_clone_lock(const struct sock sk, const gfp_t priority)
		* as not suitable for copying when cloning.
		*/
		if (sk_user_data_is_nocopy(newsk))
		RCU_INIT_POINTER(newsk->sk_user_data, NULL);
		newsk->sk_user_data = NULL;

		newsk->sk_err = 0;
		newsk->sk_err_soft = 0;

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