Matias Denda 1dde97f807 Fix stack buffer overflow in aes_ccm_encr for partial blocks (#11347) ...

* Fix out-of-bounds write in aes_ccm_encr for partial blocks

aes_ccm_encr() writes a full 16-byte AES block to the output before XOR-ing with
the input, so a trailing partial block writes up to 15 bytes past the length the
caller asked for. Every caller in the tree passes a buffer with enough slack, so
nothing misbehaves today, but the decrypt path clears it by only a few bytes.

Encrypt into a temporary block and XOR out of it, matching what
aes_ccm_encr_auth() and aes_ccm_decr_auth() already do in this same file. The
ciphertext is unchanged.

* Add regression test for the CCM partial-block write and drop stale workarounds

The guard bytes past the caller's buffer catch the overflow without relying on a
sanitizer, so the test is meaningful in the native environment too.

encryptCurve25519() no longer needs to write extraNonce before aes_ccm_ae(): the
call stays inside numBytes now, so the copy after it is the only one required.
The comment warning about the 15-byte overshoot no longer describes the code.

2026-08-04 22:31:38 +00:00

..

test_main.cpp

Fix stack buffer overflow in aes_ccm_encr for partial blocks (#11347)

2026-08-04 22:31:38 +00:00