Messages in this thread | | | Subject | Re: [PATCH v3] net: xfrm: Add '_rcu' tag for rcu protected pointer in netns_xfrm | From | "Su Yanjun <>" <> | Date | Wed, 20 Mar 2019 08:53:54 +0800 |
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On 2019/3/19 23:15, Steffen Klassert wrote: > On Mon, Mar 18, 2019 at 10:22:46AM -0700, Eric Dumazet wrote: >> >> On 03/11/2019 03:10 AM, Steffen Klassert wrote: >>> On Wed, Mar 06, 2019 at 08:54:08PM -0500, Su Yanjun wrote: >>>> For rcu protected pointers, we'd better add '__rcu' for them. >>>> >>>> Once added '__rcu' tag for rcu protected pointer, the sparse tool reports >>>> warnings. >>>> >>>> net/xfrm/xfrm_user.c:1198:39: sparse: expected struct sock *sk >>>> net/xfrm/xfrm_user.c:1198:39: sparse: got struct sock [noderef] <asn:4> *nlsk >>>> [...] >>>> >>>> So introduce a new wrapper function of nlmsg_unicast to handle type >>>> conversions. >>>> >>>> This patch also fixes a direct access of a rcu protected socket. >>>> >>>> Fixes: be33690d8fcf("[XFRM]: Fix aevent related crash") >>>> Signed-off-by: Su Yanjun <suyj.fnst@cn.fujitsu.com> >>> Patch applied, thanks! >>> >> Has this patch ever been tested ? > I had this on your testing system and it did > not complain. But maybe my testcases did not > trigger that codepath. Su, can you answer > on Eric question? > Firs of all, I didn't produce it on my test machine.
Maybe we need recompile the kernel with Eric Dumazet's advise.
CONFIG_LOCKDEP=y CONFIG_PROVE_RCU=y
The second the code path indeed doesn't do as below: rcu_read_lock() rcu_dereference() ... rcu_read_unlock()
All rcu_dereference are in the follow code path: xfrm_user_rcv_msg link->doit(skb, nlh, attrs) rcu_dereference()
I think we can add rcu protection for nlsock
xfrm_user_rcv_msg rcu_read_lock() link->doit(skb, nlh, attrs) rcu_read_unlock()
Any advise?
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