Syscall-side map_lookup_elem() and map_update_elem() used to use kmalloc() to allocate temporary buffers of value_size, so KMALLOC_MAX_SIZE limit on value_size made sense to prevent creation of array map that won't be accessible through syscall interface. But this limitation since has been lifted by relying on kvmalloc() in syscall handling code. So remove KMALLOC_MAX_SIZE, which among other things means that it's possible to have BPF global variable sections (.bss, .data, .rodata) bigger than 8MB now. Keep the sanity check to prevent trivial overflows like round_up(map->value_size, 8) and restrict value size to <= INT_MAX (2GB). Signed-off-by: Andrii Nakryiko <andrii@xxxxxxxxxx> --- kernel/bpf/arraymap.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c index 98ee09155151..d3e734bf8056 100644 --- a/kernel/bpf/arraymap.c +++ b/kernel/bpf/arraymap.c @@ -70,10 +70,8 @@ int array_map_alloc_check(union bpf_attr *attr) attr->map_flags & BPF_F_PRESERVE_ELEMS) return -EINVAL; - if (attr->value_size > KMALLOC_MAX_SIZE) - /* if value_size is bigger, the user space won't be able to - * access the elements. - */ + /* avoid overflow on round_up(map->value_size) */ + if (attr->value_size > INT_MAX) return -E2BIG; return 0; -- 2.30.2
