Fix OCB AES-NI/HW stream path unauthenticated/unencrypted trailing bytes

When ctx->stream (e.g., AES‑NI or ARMv8 CE) is available, the fast path
encrypts/decrypts full blocks but does not advance in/out pointers. The
tail-handling code then operates on the base pointers, effectively reprocessing
the beginning of the buffer while leaving the actual trailing bytes
unencrypted (encryption) or using the wrong plaintext (decryption). The
authentication checksum excludes the true tail.

CVE-2025-69418

Fixes: https://github.com/openssl/srt/issues/58
Signed-off-by: Norbert Pocs <norbertp@openssl.org>
Reviewed-by: Saša Nedvědický <sashan@openssl.org>
Reviewed-by: Eugene Syromiatnikov <esyr@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
MergeDate: Mon Jan 26 19:48:35 2026

diff --git a/crypto/modes/ocb128.c b/crypto/modes/ocb128.c
index ce72baf6da5a771aa0f6635b0807135d7640d9a6..8a5d7c7db00b5107fbf8b907fe40c788193fa91a 100644 (file)
--- a/crypto/modes/ocb128.c
+++ b/crypto/modes/ocb128.c
@@ -337,7 +337,7 @@ int CRYPTO_ocb128_encrypt(OCB128_CONTEXT *ctx,
 
     if (num_blocks && all_num_blocks == (size_t)all_num_blocks
         && ctx->stream != NULL) {
-        size_t max_idx = 0, top = (size_t)all_num_blocks;
+        size_t max_idx = 0, top = (size_t)all_num_blocks, processed_bytes = 0;
 
         /*
          * See how many L_{i} entries we need to process data at hand
@@ -351,6 +351,9 @@ int CRYPTO_ocb128_encrypt(OCB128_CONTEXT *ctx,
         ctx->stream(in, out, num_blocks, ctx->keyenc,
             (size_t)ctx->sess.blocks_processed + 1, ctx->sess.offset.c,
             (const unsigned char (*)[16])ctx->l, ctx->sess.checksum.c);
+        processed_bytes = num_blocks * 16;
+        in += processed_bytes;
+        out += processed_bytes;
     } else {
         /* Loop through all full blocks to be encrypted */
         for (i = ctx->sess.blocks_processed + 1; i <= all_num_blocks; i++) {
@@ -429,7 +432,7 @@ int CRYPTO_ocb128_decrypt(OCB128_CONTEXT *ctx,
 
     if (num_blocks && all_num_blocks == (size_t)all_num_blocks
         && ctx->stream != NULL) {
-        size_t max_idx = 0, top = (size_t)all_num_blocks;
+        size_t max_idx = 0, top = (size_t)all_num_blocks, processed_bytes = 0;
 
         /*
          * See how many L_{i} entries we need to process data at hand
@@ -443,6 +446,9 @@ int CRYPTO_ocb128_decrypt(OCB128_CONTEXT *ctx,
         ctx->stream(in, out, num_blocks, ctx->keydec,
             (size_t)ctx->sess.blocks_processed + 1, ctx->sess.offset.c,
             (const unsigned char (*)[16])ctx->l, ctx->sess.checksum.c);
+        processed_bytes = num_blocks * 16;
+        in += processed_bytes;
+        out += processed_bytes;
     } else {
         OCB_BLOCK tmp;