From b2663d527a1992ba98c0266458b21ada3b9d0d2e Mon Sep 17 00:00:00 2001 From: Changqing Li Date: Thu, 27 Feb 2020 12:07:35 +0800 Subject: [PATCH] tcp_emu: Fix oob access The main loop only checks for one available byte, while we sometimes need two bytes. CVE: CVE-2020-7039 Upstream-Status: Backport [https://gitlab.freedesktop.org/slirp/libslirp/commit/2655fffed7a9e765bcb4701dd876e9dab975f289] Signed-off-by: Changqing Li --- slirp/src/tcp_subr.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/slirp/src/tcp_subr.c b/slirp/src/tcp_subr.c index d6dd133..4bea2d4 100644 --- a/slirp/src/tcp_subr.c +++ b/slirp/src/tcp_subr.c @@ -886,6 +886,8 @@ 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 @@ -901,6 +903,10 @@ 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 */ -- 2.7.4