If bits is 0, the case when the map is empty, then the >> is the size of the register which is undefined behavior - on x86 it is the same as a shift by 0. Avoid calling hash_bits with bits == 0 by adding additional empty hashmap tests.
Suggested-by: Andrii Nakryiko <[email protected]>, Suggested-by: Song Liu <[email protected]> Signed-off-by: Ian Rogers <[email protected]> --- tools/lib/bpf/hashmap.c | 12 ++++++++++-- tools/lib/bpf/hashmap.h | 12 ++++++------ 2 files changed, 16 insertions(+), 8 deletions(-) diff --git a/tools/lib/bpf/hashmap.c b/tools/lib/bpf/hashmap.c index 3c20b126d60d..41e6f636101e 100644 --- a/tools/lib/bpf/hashmap.c +++ b/tools/lib/bpf/hashmap.c @@ -156,7 +156,7 @@ int hashmap__insert(struct hashmap *map, const void *key, void *value, const void **old_key, void **old_value) { struct hashmap_entry *entry; - size_t h; + size_t h = 0; int err; if (old_key) @@ -164,7 +164,9 @@ int hashmap__insert(struct hashmap *map, const void *key, void *value, if (old_value) *old_value = NULL; - h = hash_bits(map->hash_fn(key, map->ctx), map->cap_bits); + if (map->buckets) + h = hash_bits(map->hash_fn(key, map->ctx), map->cap_bits); + if (strategy != HASHMAP_APPEND && hashmap_find_entry(map, key, h, NULL, &entry)) { if (old_key) @@ -208,6 +210,9 @@ bool hashmap__find(const struct hashmap *map, const void *key, void **value) struct hashmap_entry *entry; size_t h; + if (!map->buckets) + return false; + h = hash_bits(map->hash_fn(key, map->ctx), map->cap_bits); if (!hashmap_find_entry(map, key, h, NULL, &entry)) return false; @@ -223,6 +228,9 @@ bool hashmap__delete(struct hashmap *map, const void *key, struct hashmap_entry **pprev, *entry; size_t h; + if (!map->buckets) + return false; + h = hash_bits(map->hash_fn(key, map->ctx), map->cap_bits); if (!hashmap_find_entry(map, key, h, &pprev, &entry)) return false; diff --git a/tools/lib/bpf/hashmap.h b/tools/lib/bpf/hashmap.h index d9b385fe808c..61236437876e 100644 --- a/tools/lib/bpf/hashmap.h +++ b/tools/lib/bpf/hashmap.h @@ -174,17 +174,17 @@ bool hashmap__find(const struct hashmap *map, const void *key, void **value); * @key: key to iterate entries for */ #define hashmap__for_each_key_entry(map, cur, _key) \ - for (cur = ({ size_t bkt = hash_bits(map->hash_fn((_key), map->ctx),\ - map->cap_bits); \ - map->buckets ? map->buckets[bkt] : NULL; }); \ + for (cur = map->buckets \ + ? map->buckets[hash_bits(map->hash_fn((_key), map->ctx), map->cap_bits)] \ + : NULL; \ cur; \ cur = cur->next) \ if (map->equal_fn(cur->key, (_key), map->ctx)) #define hashmap__for_each_key_entry_safe(map, cur, tmp, _key) \ - for (cur = ({ size_t bkt = hash_bits(map->hash_fn((_key), map->ctx),\ - map->cap_bits); \ - cur = map->buckets ? map->buckets[bkt] : NULL; }); \ + for (cur = map->buckets \ + ? map->buckets[hash_bits(map->hash_fn((_key), map->ctx), map->cap_bits)] \ + : NULL; \ cur && ({ tmp = cur->next; true; }); \ cur = tmp) \ if (map->equal_fn(cur->key, (_key), map->ctx)) -- 2.29.1.341.ge80a0c044ae-goog
