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Multiblock corrupted pointer fix

OpenSSL 1.0.2 introduced the "multiblock" performance improvement. This
feature only applies on 64 bit x86 architecture platforms that support AES
NI instructions. A defect in the implementation of "multiblock" can cause
OpenSSL's internal write buffer to become incorrectly set to NULL when
using non-blocking IO. Typically, when the user application is using a
socket BIO for writing, this will only result in a failed connection.
However if some other BIO is used then it is likely that a segmentation
fault will be triggered, thus enabling a potential DoS attack.


Reviewed-by: Richard Levitte <>
Reviewed-by: Andy Polyakov <>
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mattcaswell committed Mar 2, 2015
1 parent 7ead0c8 commit 1d2a18dc5a3b3363e17db5af8b6b0273856ac077
Showing with 1 addition and 1 deletion.
  1. +1 −1 ssl/s3_pkt.c
@@ -804,7 +804,7 @@ int ssl3_write_bytes(SSL *s, int type, const void *buf_, int len)

i = ssl3_write_pending(s, type, &buf[tot], nw);
if (i <= 0) {
if (i < 0) {
if (i < 0 && (!s->wbio || !BIO_should_retry(s->wbio))) {
wb->buf = NULL;

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