bpf: do not use KMALLOC_SHIFT_MAX

Commit 01b3f52 ("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/[email protected] Signed-off-by: Michal Hocko <[email protected]> Acked-by: Christoph Lameter <[email protected]> Cc: Alexei Starovoitov <[email protected]> Cc: Andrey Konovalov <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
anholt · Jan 11, 2017 · 7984c27 · 7984c27
1 parent bb1107f
commit 7984c27
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Showing 2 changed files with 2 additions and 2 deletions.
diff --git 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
@@ -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