CVE-2026-53076

In the Linux kernel, the following vulnerability has been resolved:

bpf: Fix OOB in pcpu_init_value

An out-of-bounds read occurs when copying element from a

BPF_MAP_TYPE_CGROUP_STORAGE map to another pcpu map with the

same value_size that is not rounded up to 8 bytes.

The issue happens when:

1. A CGROUP_STORAGE map is created with value_size not aligned to

8 bytes (e.g., 4 bytes)

2. A pcpu map is created with the same value_size (e.g., 4 bytes)

3. Update element in 2 with data in 1

pcpu_init_value assumes that all sources are rounded up to 8 bytes,

and invokes copy_map_value_long to make a data copy, However, the

assumption doesn't stand since there are some cases where the source

may not be rounded up to 8 bytes, e.g., CGROUP_STORAGE, skb->data.

the verifier verifies exactly the size that the source claims, not

the size rounded up to 8 bytes by kernel, an OOB happens when the

source has only 4 bytes while the copy size(4) is rounded up to 8.