diff options
| author | Song Liu <songliubraving@fb.com> | 2021-02-26 00:43:15 +0100 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2021-02-26 20:51:48 +0100 |
| commit | bc235cdb423a2daed6f337676006a66557429cd1 (patch) | |
| tree | 397fc9c1c0b454bfe2856b9f70cbf08e1467d396 /net/core | |
| parent | bpf: Enable task local storage for tracing programs (diff) | |
| download | linux-bc235cdb423a2daed6f337676006a66557429cd1.tar.xz linux-bc235cdb423a2daed6f337676006a66557429cd1.zip | |
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 'net/core')
| -rw-r--r-- | net/core/bpf_sk_storage.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/net/core/bpf_sk_storage.c b/net/core/bpf_sk_storage.c index 4edd033e899c..cc3712ad8716 100644 --- a/net/core/bpf_sk_storage.c +++ b/net/core/bpf_sk_storage.c @@ -89,7 +89,7 @@ static void bpf_sk_storage_map_free(struct bpf_map *map) smap = (struct bpf_local_storage_map *)map; bpf_local_storage_cache_idx_free(&sk_cache, smap->cache_idx); - bpf_local_storage_map_free(smap); + bpf_local_storage_map_free(smap, NULL); } static struct bpf_map *bpf_sk_storage_map_alloc(union bpf_attr *attr) |