From 864036e251f54c99d31df124aad7f34f01f5344c Mon Sep 17 00:00:00 2001 From: Prasad J Pandit Date: Tue, 5 Jun 2018 23:38:35 +0530 Subject: slirp: correct size computation while concatenating mbuf 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 Signed-off-by: Samuel Thibault --- slirp/mbuf.c | 11 +++++------ 1 file changed, 5 insertions(+), 6 deletions(-) (limited to 'slirp/mbuf.c') diff --git a/slirp/mbuf.c b/slirp/mbuf.c index 5ff24559fd..18cbf759a7 100644 --- a/slirp/mbuf.c +++ b/slirp/mbuf.c @@ -138,7 +138,7 @@ 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); + 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; @@ -147,7 +147,7 @@ m_cat(struct mbuf *m, struct mbuf *n) } -/* make m size bytes large */ +/* make m 'size' bytes large from m_data */ void m_inc(struct mbuf *m, int size) { @@ -158,12 +158,12 @@ 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; @@ -171,8 +171,7 @@ m_inc(struct mbuf *m, int size) m->m_flags |= M_EXT; } - m->m_size = size; - + m->m_size = size + datasize; } -- cgit 1.4.1