The branch OpenSSL_1_1_1-stable has been updated via df943912046aee2e5e541949dbdbafa38819f195 (commit) from fa41bbe00ef03cf7f8bb0c6f20fa59d451fc7bca (commit)
- Log ----------------------------------------------------------------- commit df943912046aee2e5e541949dbdbafa38819f195 Author: Matt Caswell <m...@openssl.org> Date: Fri May 8 11:12:10 2020 +0100 Correct alignment calculation in ssl3_setup_write The alignment calculation in ssl3_setup_write incorrectly results in an alignment allowance of (-SSL3_RT_HEADER_LENGTH) & (SSL3_ALIGN_PAYLOAD - 1) bytes. This equals 3 in almost all cases. The maximum alignment actually used in do_ssl3_write is (SSL3_ALIGN_PAYLOAD - 1). This equals 7 bytes in almost all cases. So there is a potential to overrun the buffer by up to 4 bytes. Fortunately, the encryption overhead allowed for is 80 bytes which consists of 16 bytes for the cipher block size and 64 bytes for the MAC output. However the biggest MAC that we ever produce is HMAC-384 which is 48 bytes - so we have a headroom of 16 bytes (i.e. more than the 4 bytes of potential overrun). Thanks to Nagesh Hegde for reporting this. Fixes #11766 Reviewed-by: Ben Kaduk <ka...@mit.edu> (Merged from https://github.com/openssl/openssl/pull/11768) (cherry picked from commit d30ef639647ad263d09740c931a5bfb5a8b6a5f6) ----------------------------------------------------------------------- Summary of changes: ssl/record/ssl3_buffer.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/ssl/record/ssl3_buffer.c b/ssl/record/ssl3_buffer.c index 605f8f9b75..56c0d78b12 100644 --- a/ssl/record/ssl3_buffer.c +++ b/ssl/record/ssl3_buffer.c @@ -94,7 +94,7 @@ int ssl3_setup_write_buffer(SSL *s, size_t numwpipes, size_t len) headerlen = SSL3_RT_HEADER_LENGTH; #if defined(SSL3_ALIGN_PAYLOAD) && SSL3_ALIGN_PAYLOAD!=0 - align = (-SSL3_RT_HEADER_LENGTH) & (SSL3_ALIGN_PAYLOAD - 1); + align = SSL3_ALIGN_PAYLOAD - 1; #endif len = ssl_get_max_send_fragment(s)