bpf: do not use KMALLOC_SHIFT_MAX

Commit 01b3f52157ff ("bpf: fix allocation warnings in bpf maps and
integer overflow") has added checks for the maximum allocateable size.
It (ab)used KMALLOC_SHIFT_MAX for that purpose.

While this is not incorrect it is not very clean because we already have
KMALLOC_MAX_SIZE for this very reason so let's change both checks to use
KMALLOC_MAX_SIZE instead.

The original motivation for using KMALLOC_SHIFT_MAX was to work around
an incorrect KMALLOC_MAX_SIZE which could lead to allocation warnings
but it is no longer needed since "slab: make sure that KMALLOC_MAX_SIZE
will fit into MAX_ORDER".

Link: http://lkml.kernel.org/r/20161220130659.16461-3-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c
index a2ac051c342f87b1372a7aeb33ba816327ee1a43..229a5d5df9770fc66774bf5defea359873946d01 100644 (file)
--- a/kernel/bpf/arraymap.c
+++ b/kernel/bpf/arraymap.c
@@ -56,7 +56,7 @@ static struct bpf_map *array_map_alloc(union bpf_attr *attr)
            attr->value_size == 0 || attr->map_flags)
                return ERR_PTR(-EINVAL);
 
-       if (attr->value_size >= 1 << (KMALLOC_SHIFT_MAX - 1))
+       if (attr->value_size > KMALLOC_MAX_SIZE)
                /* if value_size is bigger, the user space won't be able to
                 * access the elements.
                 */

diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c
index 34debc1a9641875382b6603820f3e85c4a18dffc..3f2bb58952d8dfa4a2e082f9e6f9d277e19f0577 100644 (file)
--- a/kernel/bpf/hashtab.c
+++ b/kernel/bpf/hashtab.c
@@ -274,7 +274,7 @@ static struct bpf_map *htab_map_alloc(union bpf_attr *attr)
                 */
                goto free_htab;
 
-       if (htab->map.value_size >= (1 << (KMALLOC_SHIFT_MAX - 1)) -
+       if (htab->map.value_size >= KMALLOC_MAX_SIZE -
            MAX_BPF_STACK - sizeof(struct htab_elem))
                /* if value_size is bigger, the user space won't be able to
                 * access the elements via bpf syscall. This check also makes