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| author |   Andrii Nakryiko <andrii@kernel.org> | 2022-07-14 22:31:43 -0700 |
|---|---|---|
| committer |   Alexei Starovoitov <ast@kernel.org> | 2022-07-19 09:45:34 -0700 |
| commit | 87ac0d600943994444e24382a87aa19acc4cd3d4 (patch) | |
| tree | e4af751c0f261ec49b5d6d6221ef26cf7ff99348 /kernel/bpf/arraymap.c | |
| parent | docs/bpf: Update documentation for BTF_KIND_FUNC (diff) | |
| download | linux-dev-87ac0d600943994444e24382a87aa19acc4cd3d4.tar.xz linux-dev-87ac0d600943994444e24382a87aa19acc4cd3d4.zip | |
bpf: fix potential 32-bit overflow when accessing ARRAY map element
If BPF array map is bigger than 4GB, element pointer calculation can
overflow because both index and elem_size are u32. Fix this everywhere
by forcing 64-bit multiplication. Extract this formula into separate
small helper and use it consistently in various places.
Speculative-preventing formula utilizing index_mask trick is left as is,
but explicit u64 casts are added in both places.
Fixes: c85d69135a91 ("bpf: move memory size checks to bpf_map_charge_init()")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20220715053146.1291891-2-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'kernel/bpf/arraymap.c')
| -rw-r--r-- | kernel/bpf/arraymap.c | 20 |
1 files changed, 12 insertions, 8 deletions
diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c index fe40d3b9458f..1d05d63e6fa5 100644 --- a/kernel/bpf/arraymap.c +++ b/kernel/bpf/arraymap.c @@ -156,6 +156,11 @@ static struct bpf_map *array_map_alloc(union bpf_attr *attr) return &array->map; } +static void *array_map_elem_ptr(struct bpf_array* array, u32 index) +{ + return array->value + (u64)array->elem_size * index; +} + /* Called from syscall or from eBPF program */ static void *array_map_lookup_elem(struct bpf_map *map, void *key) { @@ -165,7 +170,7 @@ static void *array_map_lookup_elem(struct bpf_map *map, void *key) if (unlikely(index >= array->map.max_entries)) return NULL; - return array->value + array->elem_size * (index & array->index_mask); + return array->value + (u64)array->elem_size * (index & array->index_mask); } static int array_map_direct_value_addr(const struct bpf_map *map, u64 *imm, @@ -339,7 +344,7 @@ static int array_map_update_elem(struct bpf_map *map, void *key, void *value, value, map->value_size); } else { val = array->value + - array->elem_size * (index & array->index_mask); + (u64)array->elem_size * (index & array->index_mask); if (map_flags & BPF_F_LOCK) copy_map_value_locked(map, val, value, false); else @@ -408,8 +413,7 @@ static void array_map_free_timers(struct bpf_map *map) return; for (i = 0; i < array->map.max_entries; i++) - bpf_timer_cancel_and_free(array->value + array->elem_size * i + - map->timer_off); + bpf_timer_cancel_and_free(array_map_elem_ptr(array, i) + map->timer_off); } /* Called when map->refcnt goes to zero, either from workqueue or from syscall */ @@ -420,7 +424,7 @@ static void array_map_free(struct bpf_map *map) if (map_value_has_kptrs(map)) { for (i = 0; i < array->map.max_entries; i++) - bpf_map_free_kptrs(map, array->value + array->elem_size * i); + bpf_map_free_kptrs(map, array_map_elem_ptr(array, i)); bpf_map_free_kptr_off_tab(map); } @@ -556,7 +560,7 @@ static void *bpf_array_map_seq_start(struct seq_file *seq, loff_t *pos) index = info->index & array->index_mask; if (info->percpu_value_buf) return array->pptrs[index]; - return array->value + array->elem_size * index; + return array_map_elem_ptr(array, index); } static void *bpf_array_map_seq_next(struct seq_file *seq, void *v, loff_t *pos) @@ -575,7 +579,7 @@ static void *bpf_array_map_seq_next(struct seq_file *seq, void *v, loff_t *pos) index = info->index & array->index_mask; if (info->percpu_value_buf) return array->pptrs[index]; - return array->value + array->elem_size * index; + return array_map_elem_ptr(array, index); } static int __bpf_array_map_seq_show(struct seq_file *seq, void *v) @@ -690,7 +694,7 @@ static int bpf_for_each_array_elem(struct bpf_map *map, bpf_callback_t callback_ if (is_percpu) val = this_cpu_ptr(array->pptrs[i]); else - val = array->value + array->elem_size * i; + val = array_map_elem_ptr(array, i); num_elems++; key = i; ret = callback_fn((u64)(long)map, (u64)(long)&key, |