bpf: Set uattr->batch.count as zero before batched update or deletion

generic_map_{delete,update}_batch() doesn't set uattr->batch.count as
zero before it tries to allocate memory for key. If the memory
allocation fails, the value of uattr->batch.count will be incorrect.

Fix it by setting uattr->batch.count as zero beore batched update or
deletion.

Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20231208102355.2628918-6-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index dd641475b65ffcd606ba0cafb34348685ac4996a..06320d9abf3392e1956ba4d76e45258202c9f35f 100644 (file)
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -1731,6 +1731,9 @@ int generic_map_delete_batch(struct bpf_map *map,
        if (!max_count)
                return 0;
 
+       if (put_user(0, &uattr->batch.count))
+               return -EFAULT;
+
        key = kvmalloc(map->key_size, GFP_USER | __GFP_NOWARN);
        if (!key)
                return -ENOMEM;
@@ -1787,6 +1790,9 @@ int generic_map_update_batch(struct bpf_map *map, struct file *map_file,
        if (!max_count)
                return 0;
 
+       if (put_user(0, &uattr->batch.count))
+               return -EFAULT;
+
        key = kvmalloc(map->key_size, GFP_USER | __GFP_NOWARN);
        if (!key)
                return -ENOMEM;