[PATCH 5.10 v2 1/3] Revert "bpf: Fix DEVMAP_HASH overflow check on 32-bit arches"

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From: Pu Lehui <pulehui@xxxxxxxxxx>

This reverts commit 225da02acdc97af01b6bc6ce1a3e5362bf01d3fb.

Commit 225da02acdc9 ("bpf: fix DEVMAP_HASH overflow check on 32-bit
architectures") relies on the v5.11+ base mechanism of memcg-based
memory accounting[0], which is not yet supported on the 5.10 stable
branch, so let's revert this commit in preparation for re-adapting it.

Link: https://lore.kernel.org/bpf/20201201215900.3569844-1-guro@xxxxxx [0]
Signed-off-by: Pu Lehui <pulehui@xxxxxxxxxx>
---
 kernel/bpf/devmap.c | 11 +++++------
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c
index 07b5edb2c70f..ca2cade2871b 100644
--- a/kernel/bpf/devmap.c
+++ b/kernel/bpf/devmap.c
@@ -129,14 +129,13 @@ static int dev_map_init_map(struct bpf_dtab *dtab, union bpf_attr *attr)
 	bpf_map_init_from_attr(&dtab->map, attr);
 
 	if (attr->map_type == BPF_MAP_TYPE_DEVMAP_HASH) {
-		/* hash table size must be power of 2; roundup_pow_of_two() can
-		 * overflow into UB on 32-bit arches, so check that first
-		 */
-		if (dtab->map.max_entries > 1UL << 31)
-			return -EINVAL;
-
 		dtab->n_buckets = roundup_pow_of_two(dtab->map.max_entries);
 
+		if (!dtab->n_buckets) /* Overflow check */
+			return -EINVAL;
+	}
+
+	if (attr->map_type == BPF_MAP_TYPE_DEVMAP_HASH) {
 		dtab->dev_index_head = dev_map_create_hash(dtab->n_buckets,
 							   dtab->map.numa_node);
 		if (!dtab->dev_index_head)
-- 
2.34.1





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