]> git.ipfire.org Git - thirdparty/kernel/stable.git/commit
bpf: Use this_cpu_{inc|dec|inc_return} for bpf_task_storage_busy
authorHou Tao <houtao1@huawei.com>
Thu, 1 Sep 2022 06:19:35 +0000 (14:19 +0800)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Mon, 24 Oct 2022 07:57:07 +0000 (09:57 +0200)
commitecbbef374ce5fad877104e107e180ce2fb3ce3b5
treef11b85cedbcc82c817583e274587ac04c1353ee8
parent75d287186b98d2b7058d759a0d8ba963e5a4bd25
bpf: Use this_cpu_{inc|dec|inc_return} for bpf_task_storage_busy

[ Upstream commit 197827a05e13808c60f52632e9887eede63f1c16 ]

Now migrate_disable() does not disable preemption and under some
architectures (e.g. arm64) __this_cpu_{inc|dec|inc_return} are neither
preemption-safe nor IRQ-safe, so for fully preemptible kernel concurrent
lookups or updates on the same task local storage and on the same CPU
may make bpf_task_storage_busy be imbalanced, and
bpf_task_storage_trylock() on the specific cpu will always fail.

Fixing it by using this_cpu_{inc|dec|inc_return} when manipulating
bpf_task_storage_busy.

Fixes: bc235cdb423a ("bpf: Prevent deadlock from recursive bpf_task_storage_[get|delete]")
Signed-off-by: Hou Tao <houtao1@huawei.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/r/20220901061938.3789460-2-houtao@huaweicloud.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
kernel/bpf/bpf_local_storage.c
kernel/bpf/bpf_task_storage.c