From 8b7c3b6914f19caf648d05726a86af6326d3c2c6 Mon Sep 17 00:00:00 2001 From: Harald Freudenberger Date: Mon, 31 Aug 2026 10:37:34 +0200 Subject: [PATCH] s390/crypto: Fix missing scrub of temp buffers with AES ctr and gcm algorithm In function ctr_aes_crypt() there is a buffer used to process remaining bytes < AES_BLOCK_SIZE. This buffer was not scrubbed and thus could lead to expose of unwanted data. When the buffer is used explicitly scrub it at the end of the code block to avoid exposure of maybe sensitive data. In a similar way the function gcm_aes_crypt() hat an error path where the CPACF param block was not scrubbed. Instead of return early now these error paths go to end of function where explicit scrubbing is done. Similar with the buffers which are part of the gcm_sg_walk structs from the variables gw_in and gw_out. Fixes: d07f951903fa ("crypto: s390/aes - Fix buffer overread in CTR mode") Signed-off-by: Harald Freudenberger Reviewed-by: Holger Dengler Cc: stable@vger.kernel.org # 6.8+ Signed-off-by: Heiko Carstens Signed-off-by: Vasily Gorbik --- arch/s390/crypto/aes_s390.c | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-) diff --git a/arch/s390/crypto/aes_s390.c b/arch/s390/crypto/aes_s390.c index 366ce22d3623..10561aa687c7 100644 --- a/arch/s390/crypto/aes_s390.c +++ b/arch/s390/crypto/aes_s390.c @@ -604,6 +604,7 @@ static int ctr_aes_crypt(struct skcipher_request *req) memcpy(walk.dst.virt.addr, buf, nbytes); crypto_inc(walk.iv, AES_BLOCK_SIZE); ret = skcipher_walk_done(&walk, 0); + memzero_explicit(buf, sizeof(buf)); } return ret; @@ -895,10 +896,14 @@ static int gcm_aes_crypt(struct aead_request *req, unsigned int flags) gw_in.ptr, aad_bytes); n = aad_bytes + pc_bytes; - if (gcm_in_walk_done(&gw_in, n) != n) - return -ENOMEM; - if (gcm_out_walk_done(&gw_out, n) != n) - return -ENOMEM; + if (gcm_in_walk_done(&gw_in, n) != n) { + ret = -ENOMEM; + goto out; + } + if (gcm_out_walk_done(&gw_out, n) != n) { + ret = -ENOMEM; + goto out; + } aadlen -= aad_bytes; pclen -= pc_bytes; } while (aadlen + pclen > 0); @@ -910,7 +915,10 @@ static int gcm_aes_crypt(struct aead_request *req, unsigned int flags) } else scatterwalk_map_and_copy(param.t, req->dst, len, taglen, 1); +out: memzero_explicit(¶m, sizeof(param)); + memzero_explicit(gw_in.buf, sizeof(gw_in.buf)); + memzero_explicit(gw_out.buf, sizeof(gw_out.buf)); return ret; }