From: Samuel Thibault Date: Wed, 8 Jan 2020 00:58:48 +0100 Subject: tcp_emu: Fix oob access Git-commit: 2655fffed7a9e765bcb4701dd876e9dab975f289 References: bsc#1161066, CVE2020-7039, bsc#1161066, CVS-2020-7039 The main loop only checks for one available byte, while we sometimes need two bytes. Signed-off-by: Bruce Rogers --- src/tcp_subr.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/slirp/src/tcp_subr.c b/slirp/src/tcp_subr.c index 6cd181c9f2875528adab3f636aec..cedbfb28686604dbb7e8e5b35dd1 100644 --- a/slirp/src/tcp_subr.c +++ b/slirp/src/tcp_subr.c @@ -887,6 +887,9 @@ int tcp_emu(struct socket *so, struct mbuf *m) break; case 5: + if (bptr == m->m_data + m->m_len - 1) + return 1; /* We need two bytes */ + /* * The difference between versions 1.0 and * 2.0 is here. For future versions of @@ -902,6 +905,10 @@ int tcp_emu(struct socket *so, struct mbuf *m) /* This is the field containing the port * number that RA-player is listening to. */ + + if (bptr == m->m_data + m->m_len - 1) + return 1; /* We need two bytes */ + lport = (((uint8_t *)bptr)[0] << 8) + ((uint8_t *)bptr)[1]; if (lport < 6970) lport += 256; /* don't know why */