Affected: Linux

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

crypto: qce - fix CCM AAD buffer underallocation

The AAD buffer allocated in qce_aead_ccm_prepare_buf_assoclen() can be smaller than the length later programmed into the DMA scatterlist.

The allocation size is currently calculated as:

ALIGN(assoclen, 16) + MAX_CCM_ADATA_HEADER_LEN

while the DMA length is set to:

ALIGN(assoclen + adata_header_len, 16)

Since ALIGN() does not distribute over addition, the allocation can be smaller than the DMA length. For example, when assoclen = 32 and adata_header_len = 2:

allocation = ALIGN(32, 16) + 6 = 38 DMA length = ALIGN(32 + 2, 16) = 48

As a result, the QCE hardware can read beyond the allocated buffer while computing the CBC-MAC over the associated data. The extra bytes are folded into the authentication tag, resulting in an incorrect tag and causing CCM self-test failures such as:

alg: aead: ccm-aes-qce encryption test failed (wrong result) on test vector 8

Fix the allocation by adding the maximum possible AAD header length before alignment:

ALIGN(assoclen + MAX_CCM_ADATA_HEADER_LEN, 16)

This guarantees that the allocated buffer is large enough for the fully padded AAD data for all supported header sizes.