From a2ed82d40964bbc0d64cd717aa0a5a892117d2e6 Mon Sep 17 00:00:00 2001 From: Viktor Szakats Date: Thu, 23 Jul 2026 10:32:04 +0200 Subject: [PATCH] openssl: fix potential OOB read/write with AES-GCM in `ssh2_cipher_crypt()` By applying two bounds checks to non-debug builds. Reported-by: Vladimir Eli Tokarev Fixes GHSA-c4f7-cvfc-33j7 Follow-up to 3c953c05d67eb1ebcfd3316f279f12c4b1d600b4 #797 Closes #2401 --- src/openssl.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/src/openssl.c b/src/openssl.c index 6a38b55b91..31ef6db371 100644 --- a/src/openssl.c +++ b/src/openssl.c @@ -945,13 +945,15 @@ int ssh2_cipher_crypt(ssh2_cipher_ctx *ctx, SSH2_CIPHER_T(algo), int encrypt, const int aadlen = (is_aesgcm && IS_FIRST(firstlast)) ? 4 : 0; /* size of AT, if present */ const int authenticationtag = IS_LAST(firstlast) ? authlen : 0; - /* length to encrypt */ - const int cryptlen = (unsigned int)blocksize - aadlen - authenticationtag; + unsigned int cryptlen; /* length to encrypt */ (void)algo; - assert(blocksize <= sizeof(buf)); - assert(cryptlen >= 0); + if(blocksize > sizeof(buf) || + blocksize < (size_t)(aadlen + authenticationtag)) + return 1; + + cryptlen = (unsigned int)blocksize - aadlen - authenticationtag; #if LIBSSH2_AES_GCM /* First block */