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| author | Anton Protopopov <aspsk@isovalent.com> | 2023-05-22 18:45:58 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-05-30 16:03:21 +0300 |
| commit | 1a9e80f757bbb1562d82e350afce2bb2f712cc3d (patch) | |
| tree | 3276fcfc559f64ff1949b23ac29aba857e3b9a32 | |
| parent | 177ee41f6162bd6c037f83ba070d2ac3bbf7c51c (diff) | |
| download | linux-1a9e80f757bbb1562d82e350afce2bb2f712cc3d.tar.xz | |
bpf: fix a memory leak in the LRU and LRU_PERCPU hash maps
commit b34ffb0c6d23583830f9327864b9c1f486003305 upstream.
The LRU and LRU_PERCPU maps allocate a new element on update before locking the
target hash table bucket. Right after that the maps try to lock the bucket.
If this fails, then maps return -EBUSY to the caller without releasing the
allocated element. This makes the element untracked: it doesn't belong to
either of free lists, and it doesn't belong to the hash table, so can't be
re-used; this eventually leads to the permanent -ENOMEM on LRU map updates,
which is unexpected. Fix this by returning the element to the local free list
if bucket locking fails.
Fixes: 20b6cc34ea74 ("bpf: Avoid hashtab deadlock with map_locked")
Signed-off-by: Anton Protopopov <aspsk@isovalent.com>
Link: https://lore.kernel.org/r/20230522154558.2166815-1-aspsk@isovalent.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | kernel/bpf/hashtab.c | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c index 4a3d0a744702..e4e7f343346f 100644 --- a/kernel/bpf/hashtab.c +++ b/kernel/bpf/hashtab.c @@ -1203,7 +1203,7 @@ static int htab_lru_map_update_elem(struct bpf_map *map, void *key, void *value, ret = htab_lock_bucket(htab, b, hash, &flags); if (ret) - return ret; + goto err_lock_bucket; l_old = lookup_elem_raw(head, hash, key, key_size); @@ -1224,6 +1224,7 @@ static int htab_lru_map_update_elem(struct bpf_map *map, void *key, void *value, err: htab_unlock_bucket(htab, b, hash, flags); +err_lock_bucket: if (ret) htab_lru_push_free(htab, l_new); else if (l_old) @@ -1326,7 +1327,7 @@ static int __htab_lru_percpu_map_update_elem(struct bpf_map *map, void *key, ret = htab_lock_bucket(htab, b, hash, &flags); if (ret) - return ret; + goto err_lock_bucket; l_old = lookup_elem_raw(head, hash, key, key_size); @@ -1349,6 +1350,7 @@ static int __htab_lru_percpu_map_update_elem(struct bpf_map *map, void *key, ret = 0; err: htab_unlock_bucket(htab, b, hash, flags); +err_lock_bucket: if (l_new) bpf_lru_push_free(&htab->lru, &l_new->lru_node); return ret; |