Fix error return check of EVP_CIPHER_CTX_ctrl() #18987
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OpenSSL can return -1 on error [1, 2], and OpenBSD's docs confirm this [3]. Existing checks check for 1 for the success value, so do the same. [1] https://github.com/openssl/openssl/blob/b3161bd9a9329be3d6bf6b29a06835e2721898bb/crypto/evp/evp_enc.c#L1530-L1531 [2] https://github.com/openssl/openssl/blob/b3161bd9a9329be3d6bf6b29a06835e2721898bb/crypto/evp/evp_enc.c#L1611 [3] https://man.openbsd.org/EVP_CIPHER_CTX_ctrl.3
bukka
reviewed
Jul 15, 2025
ext/openssl/openssl.c
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| } | ||
| if (mode->set_tag_length_always || (enc && mode->set_tag_length_when_encrypting)) { | ||
| if (!EVP_CIPHER_CTX_ctrl(cipher_ctx, mode->aead_set_tag_flag, tag_len, NULL)) { | ||
| if (EVP_CIPHER_CTX_ctrl(cipher_ctx, mode->aead_set_tag_flag, tag_len, NULL) != 1) { |
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I just checked OpenSSL checks for EVP_CTRL_AEAD_SET_TAG and it usually uses <= 0 so think we should use that too. There was actually one usage != 1 so it might be safe but I would still prefer <= 0. Also this issue (checking for zero) is present in few places in OpenSSL itself...
bukka
approved these changes
Jul 15, 2025
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OpenSSL can return -1 on error [1, 2], and OpenBSD's docs confirm this [3]. Existing checks check for 1 for the success value, so do the same.
[1] https://github.com/openssl/openssl/blob/b3161bd9a9329be3d6bf6b29a06835e2721898bb/crypto/evp/evp_enc.c#L1530-L1531
[2] https://github.com/openssl/openssl/blob/b3161bd9a9329be3d6bf6b29a06835e2721898bb/crypto/evp/evp_enc.c#L1611
[3] https://man.openbsd.org/EVP_CIPHER_CTX_ctrl.3
This is the first batch of potentially a few of these fixes. #18986 prompted me to dig up my old analyzer and re-run it with the combined codebases of PHP and OpenSSL to check for inconsistencies.