Patch "cls_bpf: don't decrement net's refcount when offload fails" has been added to the 4.14-stable tree

This is a note to let you know that I've just added the patch titled

cls_bpf: don't decrement net's refcount when offload fails

to the 4.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
cls_bpf-don-t-decrement-net-s-refcount-when-offload-fails.patch
and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Jakub Kicinski <[email protected]>
Date: Mon, 27 Nov 2017 11:11:41 -0800
Subject: cls_bpf: don't decrement net's refcount when offload fails

From: Jakub Kicinski <[email protected]>

[ Upstream commit 25415cec502a1232b19fffc85465882b19a90415 ]

When cls_bpf offload was added it seemed like a good idea to call cls_bpf_delete_prog() instead of extending the error handling path, since the software state is fully initialized at that point. This handling of errors without jumping to the end of the function is error prone, as proven by later commit missing that extra call to __cls_bpf_delete_prog().

__cls_bpf_delete_prog() is now expected to be invoked with a reference on exts->net or the field zeroed out. The call on the offload's error patch does not fullfil this requirement, leading to each error stealing a reference on net namespace.

Create a function undoing what cls_bpf_set_parms() did and use it from __cls_bpf_delete_prog() and the error path.

---
 net/sched/cls_bpf.c |   21 +++++++++++++--------
 1 file changed, 13 insertions(+), 8 deletions(-)

@@ -246,11 +246,8 @@ static int cls_bpf_init(struct tcf_proto
 	return 0;
 }
 
-static void __cls_bpf_delete_prog(struct cls_bpf_prog *prog)
+static void cls_bpf_free_parms(struct cls_bpf_prog *prog)
 {
-	tcf_exts_destroy(&prog->exts);
-	tcf_exts_put_net(&prog->exts);
-
 	if (cls_bpf_is_ebpf(prog))
 		bpf_prog_put(prog->filter);
 	else

@@ -258,6 +255,14 @@ static void __cls_bpf_delete_prog(struct
 
 	kfree(prog->bpf_name);
 	kfree(prog->bpf_ops);
+}
+
+static void __cls_bpf_delete_prog(struct cls_bpf_prog *prog)
+{
+	tcf_exts_destroy(&prog->exts);
+	tcf_exts_put_net(&prog->exts);
+
+	cls_bpf_free_parms(prog);
 	kfree(prog);
 }
 

@@ -509,10 +514,8 @@ static int cls_bpf_change(struct net *ne
 		goto errout;
 
 	ret = cls_bpf_offload(tp, prog, oldprog);
-	if (ret) {
-		__cls_bpf_delete_prog(prog);
-		return ret;
-	}
+	if (ret)
+		goto errout_parms;
 
 	if (!tc_in_hw(prog->gen_flags))
 		prog->gen_flags |= TCA_CLS_FLAGS_NOT_IN_HW;

@@ -529,6 +532,8 @@ static int cls_bpf_change(struct net *ne
 	*arg = prog;
 	return 0;
 
+errout_parms:
+	cls_bpf_free_parms(prog);
 errout:
 	tcf_exts_destroy(&prog->exts);
 	kfree(prog);

Patches currently in stable-queue which might be from [email protected] are

queue-4.14/cls_bpf-don-t-decrement-net-s-refcount-when-offload-fails.patch