Starting in commit 7137cbf2b5 ("crypto: aes - Add cmac, xcbc, and
cbcmac algorithms using library"), the aes module (CRYPTO_AES) supports
CBC based MACs using the corresponding library functions.
To avoid including unneeded functionality, that support honors the
existing CRYPTO_CMAC, CRYPTO_XCBC, and CRYPTO_CCM kconfig options. The
dependencies are selected if at least one of those is enabled.
However, the select statements don't correctly handle the case where
CRYPTO_AES=y and (for example) CRYPTO_CMAC=m. In that case the
dependencies get selected at level 'm', due to how the kconfig language
works. That causes a linker error.
Fix this by changing the selection conditions to use '!= n'.
A similar issue also exists for CRYPTO_LIB_AES's conditional selection
of CRYPTO_LIB_UTILS. The same '!= n' would work, but instead just make
CRYPTO_LIB_AES always select CRYPTO_LIB_UTILS. CRYPTO_LIB_UTILS is
lightweight, and it's needed by most AES modes and many other things.
Fixes: 7137cbf2b5 ("crypto: aes - Add cmac, xcbc, and cbcmac algorithms using library")
Fixes: 309a7e514d ("lib/crypto: aes: Add support for CBC-based MACs")
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260709022954.45113-1-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
e073f1238e