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bpf: Fix potential call bpf_link_free() in atomic context 

The in_atomic() macro cannot always detect atomic context, in particular,
it cannot know about held spinlocks in non-preemptible kernels. Although,
there is no user call bpf_link_put() with holding spinlock now, be on the
safe side, so we can avoid this in the future.

Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Song Liu <songliubraving@fb.com>
Acked-by: Andrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200917074453.20621-1-songmuchun@bytedance.com
This commit is contained in:
Muchun Song 2020-09-17 15:44:53 +08:00 committed by Daniel Borkmann
parent 70b971118e
commit 31f23a6a18
1 changed files with 2 additions and 6 deletions
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8
kernel/bpf/syscall.c
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@ -2345,12 +2345,8 @@ void bpf_link_put(struct bpf_link *link)
if (!atomic64_dec_and_test(&link->refcnt))
return;
if (in_atomic()) {
INIT_WORK(&link->work, bpf_link_put_deferred);
schedule_work(&link->work);
} else {
bpf_link_free(link);
}
INIT_WORK(&link->work, bpf_link_put_deferred);
schedule_work(&link->work);
}
static int bpf_link_release(struct inode *inode, struct file *filp)