diff options
| author | Song Liu <songliubraving@fb.com> | 2021-02-25 15:43:15 -0800 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2021-02-26 11:51:48 -0800 |
| commit | bc235cdb423a2daed6f337676006a66557429cd1 (patch) | |
| tree | 397fc9c1c0b454bfe2856b9f70cbf08e1467d396 /include/linux/bpf_local_storage.h | |
| parent | a10787e6d58c24b51e91c19c6d16c5da89fcaa4b (diff) | |
bpf: Prevent deadlock from recursive bpf_task_storage_[get|delete]
BPF helpers bpf_task_storage_[get|delete] could hold two locks:
bpf_local_storage_map_bucket->lock and bpf_local_storage->lock. Calling
these helpers from fentry/fexit programs on functions in bpf_*_storage.c
may cause deadlock on either locks.
Prevent such deadlock with a per cpu counter, bpf_task_storage_busy. We
need this counter to be global, because the two locks here belong to two
different objects: bpf_local_storage_map and bpf_local_storage. If we
pick one of them as the owner of the counter, it is still possible to
trigger deadlock on the other lock. For example, if bpf_local_storage_map
owns the counters, it cannot prevent deadlock on bpf_local_storage->lock
when two maps are used.
Signed-off-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20210225234319.336131-3-songliubraving@fb.com
Diffstat (limited to 'include/linux/bpf_local_storage.h')
| -rw-r--r-- | include/linux/bpf_local_storage.h | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/include/linux/bpf_local_storage.h b/include/linux/bpf_local_storage.h index b2c9463f36a1..b902c580c48d 100644 --- a/include/linux/bpf_local_storage.h +++ b/include/linux/bpf_local_storage.h @@ -126,7 +126,8 @@ bpf_local_storage_lookup(struct bpf_local_storage *local_storage, struct bpf_local_storage_map *smap, bool cacheit_lockit); -void bpf_local_storage_map_free(struct bpf_local_storage_map *smap); +void bpf_local_storage_map_free(struct bpf_local_storage_map *smap, + int __percpu *busy_counter); int bpf_local_storage_map_check_btf(const struct bpf_map *map, const struct btf *btf, |