From 1f6bbceeeeb613cf4d790874bdd1e917a7071159 Mon Sep 17 00:00:00 2001 From: Daiki Ueno Date: Mon, 8 Jul 2019 16:54:56 +0200 Subject: [PATCH] ext/session_ticket: avoid calling memcpy on overlapping memory areas In _gnutls_encrypt_session_ticket, ticket.encrypted_state is allocated from ticket_data->data, thus those memory areas may overlap. Using memcpy here leads to undefined behavior. Spotted by valgrind run on ppc64le. ==95231== Source and destination overlap in memcpy(0x47ce3a2, 0x47ce3a2, 160) ==95231== at 0x408A840: memcpy (vg_replace_strmem.c:1023) ==95231== by 0x424EE9F: pack_ticket (session_ticket.c:139) ==95231== by 0x424FA4F: _gnutls_encrypt_session_ticket (session_ticket.c:335) ==95231== by 0x4199E3B: generate_session_ticket (session_ticket.c:249) ==95231== by 0x419A333: _gnutls13_send_session_ticket (session_ticket.c:307) ==95231== by 0x40F8817: _gnutls13_handshake_server (handshake-tls13.c:511) ==95231== by 0x4110DEB: handshake_server (handshake.c:3331) ==95231== by 0x410C70B: gnutls_handshake (handshake.c:2727) ==95231== by 0x10009EBF: retry_handshake (serv.c:1306) ==95231== by 0x1000AB67: tcp_server (serv.c:1500) ==95231== by 0x10009E5B: main (serv.c:1297) ==95231== Signed-off-by: Daiki Ueno --- lib/ext/session_ticket.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/lib/ext/session_ticket.c b/lib/ext/session_ticket.c index 09e240c2d..98db39ff8 100644 --- a/lib/ext/session_ticket.c +++ b/lib/ext/session_ticket.c @@ -136,7 +136,11 @@ pack_ticket(const struct ticket_st *ticket, gnutls_datum_t *ticket_data) _gnutls_write_uint16(ticket->encrypted_state_len, p); p += 2; - memcpy(p, ticket->encrypted_state, ticket->encrypted_state_len); + /* We use memmove instead of memcpy here because + * ticket->encrypted_state is allocated from + * ticket_data->data, and thus both memory areas may overlap. + */ + memmove(p, ticket->encrypted_state, ticket->encrypted_state_len); p += ticket->encrypted_state_len; memcpy(p, ticket->mac, TICKET_MAC_SIZE); -- 2.21.0