Hi all,
On Mon, 6 Apr 2020 16:29:50 +0530 Amol Grover <frextr...@gmail.com> wrote:
>
> exceptions may be traversed using list_for_each_entry_rcu()
> outside of an RCU read side critical section BUT under the
> protection of decgroup_mutex. Hence add the corresponding
> lockdep expression to fix the following false-positive
> warning:
>
> [ 2.304417] =============================
> [ 2.304418] WARNING: suspicious RCU usage
> [ 2.304420] 5.5.4-stable #17 Tainted: G E
> [ 2.304422] -----------------------------
> [ 2.304424] security/device_cgroup.c:355 RCU-list traversed in non-reader
> section!!
>
> Signed-off-by: Amol Grover <frextr...@gmail.com>
> ---
> security/device_cgroup.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/security/device_cgroup.c b/security/device_cgroup.c
> index 7d0f8f7431ff..b7da9e0970d9 100644
> --- a/security/device_cgroup.c
> +++ b/security/device_cgroup.c
> @@ -352,7 +352,8 @@ static bool match_exception_partial(struct list_head
> *exceptions, short type,
> {
> struct dev_exception_item *ex;
>
> - list_for_each_entry_rcu(ex, exceptions, list) {
> + list_for_each_entry_rcu(ex, exceptions, list,
> + lockdep_is_held(&devcgroup_mutex)) {
> if ((type & DEVCG_DEV_BLOCK) && !(ex->type & DEVCG_DEV_BLOCK))
> continue;
> if ((type & DEVCG_DEV_CHAR) && !(ex->type & DEVCG_DEV_CHAR))
> --
> 2.24.1
> I have been carrying the above patch in linux-next for some time now. I have been carrying it because it fixes problems for syzbot (see the third warning in https://lore.kernel.org/linux-next/cact4y+ynjk+kq0pfb5fe-q1bqe2t1jq_mvkhf--z80z3wky...@mail.gmail.com/). Is there some reason it has not been applied to some tree? -- Cheers, Stephen Rothwell
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