From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:48392) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fQVnL-000657-3a for qemu-devel@nongnu.org; Wed, 06 Jun 2018 06:36:03 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fQVnJ-0001e5-V0 for qemu-devel@nongnu.org; Wed, 06 Jun 2018 06:35:59 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:46592 helo=mx1.redhat.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1fQVnJ-0001dv-Qd for qemu-devel@nongnu.org; Wed, 06 Jun 2018 06:35:57 -0400 From: P J P Date: Wed, 6 Jun 2018 16:05:48 +0530 Message-Id: <20180606103549.12031-2-ppandit@redhat.com> In-Reply-To: <20180606103549.12031-1-ppandit@redhat.com> References: <20180606103549.12031-1-ppandit@redhat.com> Subject: [Qemu-devel] [PATCH v1 1/2] slirp: correct size computation while concatenating mbuf List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Qemu Developers Cc: Samuel Thibault , Jan Kiszka , Prasad J Pandit From: Prasad J Pandit While reassembling incoming fragmented datagrams, 'm_cat' routine extends the 'mbuf' buffer, if it has insufficient room. It computes a wrong buffer size, which leads to overwriting adjacent heap buffer area. Correct this size computation in m_cat. Reported-by: ZDI Disclosures Signed-off-by: Prasad J Pandit --- slirp/mbuf.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) Update v1: fixed indentation https://lists.gnu.org/archive/html/qemu-devel/2018-06/msg01121.html diff --git a/slirp/mbuf.c b/slirp/mbuf.c index 5ff24559fd..6650981fc7 100644 --- a/slirp/mbuf.c +++ b/slirp/mbuf.c @@ -137,8 +137,9 @@ m_cat(struct mbuf *m, struct mbuf *n) /* * If there's no room, realloc */ - if (M_FREEROOM(m) < n->m_len) - m_inc(m,m->m_size+MINCSIZE); + if (M_FREEROOM(m) < n->m_len) { + m_inc(m, m->m_len + n->m_len); + } memcpy(m->m_data+m->m_len, n->m_data, n->m_len); m->m_len += n->m_len; @@ -158,12 +159,12 @@ m_inc(struct mbuf *m, int size) if (m->m_flags & M_EXT) { datasize = m->m_data - m->m_ext; - m->m_ext = g_realloc(m->m_ext, size); + m->m_ext = g_realloc(m->m_ext, size + datasize); m->m_data = m->m_ext + datasize; } else { char *dat; datasize = m->m_data - m->m_dat; - dat = g_malloc(size); + dat = g_malloc(size + datasize); memcpy(dat, m->m_dat, m->m_size); m->m_ext = dat; @@ -171,7 +172,7 @@ m_inc(struct mbuf *m, int size) m->m_flags |= M_EXT; } - m->m_size = size; + m->m_size = size + datasize; } -- 2.17.1