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bpf: Do not walk twice the hash map on free

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If someone stores both a timer and a workqueue in a hash map, on free, we
would walk it twice.

Add a check in htab_free_malloced_timers_or_wq and free the timers and
workqueues if they are present.

Fixes: 246331e3f1 ("bpf: allow struct bpf_wq to be embedded in arraymaps and hashmaps")
Signed-off-by: Benjamin Tissoires <bentiss@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/bpf/20240430-bpf-next-v3-2-27afe7f3b17c@kernel.org
This commit is contained in:
Benjamin Tissoires 2024-04-30 12:43:25 +02:00 committed by Daniel Borkmann
parent b98a5c68cc
commit a891711d01
1 changed files with 13 additions and 36 deletions
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49
kernel/bpf/hashtab.c
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@ -221,13 +221,11 @@ static bool htab_has_extra_elems(struct bpf_htab *htab)
return !htab_is_percpu(htab) && !htab_is_lru(htab);
}
static void htab_free_prealloced_timers(struct bpf_htab *htab)
static void htab_free_prealloced_timers_and_wq(struct bpf_htab *htab)
{
u32 num_entries = htab->map.max_entries;
int i;
if (!btf_record_has_field(htab->map.record, BPF_TIMER))
return;
if (htab_has_extra_elems(htab))
num_entries += num_possible_cpus();
@ -235,27 +233,12 @@ static void htab_free_prealloced_timers(struct bpf_htab *htab)
struct htab_elem *elem;
elem = get_htab_elem(htab, i);
bpf_obj_free_timer(htab->map.record, elem->key + round_up(htab->map.key_size, 8));
cond_resched();
}
}
static void htab_free_prealloced_wq(struct bpf_htab *htab)
{
u32 num_entries = htab->map.max_entries;
int i;
if (!btf_record_has_field(htab->map.record, BPF_WORKQUEUE))
return;
if (htab_has_extra_elems(htab))
num_entries += num_possible_cpus();
for (i = 0; i < num_entries; i++) {
struct htab_elem *elem;
elem = get_htab_elem(htab, i);
bpf_obj_free_workqueue(htab->map.record,
elem->key + round_up(htab->map.key_size, 8));
if (btf_record_has_field(htab->map.record, BPF_TIMER))
bpf_obj_free_timer(htab->map.record,
elem->key + round_up(htab->map.key_size, 8));
if (btf_record_has_field(htab->map.record, BPF_WORKQUEUE))
bpf_obj_free_workqueue(htab->map.record,
elem->key + round_up(htab->map.key_size, 8));
cond_resched();
}
}
@ -1515,7 +1498,7 @@ static void delete_all_elements(struct bpf_htab *htab)
migrate_enable();
}
static void htab_free_malloced_timers_or_wq(struct bpf_htab *htab, bool is_timer)
static void htab_free_malloced_timers_and_wq(struct bpf_htab *htab)
{
int i;
@ -1527,10 +1510,10 @@ static void htab_free_malloced_timers_or_wq(struct bpf_htab *htab, bool is_timer
hlist_nulls_for_each_entry(l, n, head, hash_node) {
/* We only free timer on uref dropping to zero */
if (is_timer)
if (btf_record_has_field(htab->map.record, BPF_TIMER))
bpf_obj_free_timer(htab->map.record,
l->key + round_up(htab->map.key_size, 8));
else
if (btf_record_has_field(htab->map.record, BPF_WORKQUEUE))
bpf_obj_free_workqueue(htab->map.record,
l->key + round_up(htab->map.key_size, 8));
}
@ -1544,17 +1527,11 @@ static void htab_map_free_timers_and_wq(struct bpf_map *map)
struct bpf_htab *htab = container_of(map, struct bpf_htab, map);
/* We only free timer and workqueue on uref dropping to zero */
if (btf_record_has_field(htab->map.record, BPF_TIMER)) {
if (btf_record_has_field(htab->map.record, BPF_TIMER | BPF_WORKQUEUE)) {
if (!htab_is_prealloc(htab))
htab_free_malloced_timers_or_wq(htab, true);
htab_free_malloced_timers_and_wq(htab);
else
htab_free_prealloced_timers(htab);
}
if (btf_record_has_field(htab->map.record, BPF_WORKQUEUE)) {
if (!htab_is_prealloc(htab))
htab_free_malloced_timers_or_wq(htab, false);
else
htab_free_prealloced_wq(htab);
htab_free_prealloced_timers_and_wq(htab);
}
}