diff options
author | Marcus Huewe <suse-tux@gmx.de> | 2018-05-11 12:24:56 +0200 |
---|---|---|
committer | Matt Caswell <matt@openssl.org> | 2018-06-07 13:08:07 +0100 |
commit | c0a58e034d3eff68ca5e0d36d7b4d147425b0599 (patch) | |
tree | d84101a77b1ab4760bcd788eb6de4de2a0b1b7ac /crypto/hmac | |
parent | 0189bf2bbe30d4fa710fe7440ed7f3d8eab039c6 (diff) |
Do not free a session before calling the remove_session_cb
If the remove_session_cb accesses the session's data (for instance,
via SSL_SESSION_get_protocol_version), a potential use after free
can occur. For this, consider the following scenario when adding
a new session via SSL_CTX_add_session:
- The session cache is full
(SSL_CTX_sess_number(ctx) > SSL_CTX_sess_get_cache_size(ctx))
- Only the session cache has a reference to ctx->session_cache_tail
(that is, ctx->session_cache_tail->references == 1)
Since the cache is full, remove_session_lock is called to remove
ctx->session_cache_tail from the cache. That is, it
SSL_SESSION_free()s the session, which free()s the data. Afterwards,
the free()d session is passed to the remove_session_cb. If the callback
accesses the session's data, we have a use after free.
The free before calling the callback behavior was introduced in
commit e4612d02c53cccd24fa97b08fc01250d1238cca1 ("Remove sessions
from external cache, even if internal cache not used.").
CLA: trivial
Reviewed-by: Rich Salz <rsalz@openssl.org>
Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/6222)
Diffstat (limited to 'crypto/hmac')
0 files changed, 0 insertions, 0 deletions