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authorMatt Caswell <matt@openssl.org>2017-05-25 15:18:22 +0100
committerMatt Caswell <matt@openssl.org>2017-05-25 15:35:45 +0100
commite6ec6773c4ad10d6b4f260b3a2086547f2153ef1 (patch)
tree99368c9cb29eb9c29caba1c96363b3b13b251929 /doc
parentb9ff4ec746daafe520e36c1489a2f843401ab140 (diff)
Document that HMAC() with a NULL md is not thread safe
Fixes #3541 Reviewed-by: Rich Salz <rsalz@openssl.org> (Merged from https://github.com/openssl/openssl/pull/3554)
Diffstat (limited to 'doc')
-rw-r--r--doc/crypto/HMAC.pod3
1 files changed, 2 insertions, 1 deletions
diff --git a/doc/crypto/HMAC.pod b/doc/crypto/HMAC.pod
index 87f7e33086..219c9ba208 100644
--- a/doc/crypto/HMAC.pod
+++ b/doc/crypto/HMAC.pod
@@ -57,7 +57,8 @@ B<key_len> bytes long.
It places the result in B<md> (which must have space for the output of
the hash function, which is no more than B<EVP_MAX_MD_SIZE> bytes).
If B<md> is NULL, the digest is placed in a static array. The size of
-the output is placed in B<md_len>, unless it is B<NULL>.
+the output is placed in B<md_len>, unless it is B<NULL>. Note: passing a NULL
+value for B<md> to use the static array is not thread safe.
B<evp_md> can be EVP_sha1(), EVP_ripemd160() etc.