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[Qemu-devel] [PULL 4/5] slirp: correct size computation while concatenat
From: |
Samuel Thibault |
Subject: |
[Qemu-devel] [PULL 4/5] slirp: correct size computation while concatenating mbuf |
Date: |
Fri, 8 Jun 2018 09:13:15 +0300 |
From: Prasad J Pandit <address@hidden>
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 <address@hidden>
Signed-off-by: Prasad J Pandit <address@hidden>
Signed-off-by: Samuel Thibault <address@hidden>
---
slirp/mbuf.c | 11 +++++------
slirp/mbuf.h | 8 +++-----
2 files changed, 8 insertions(+), 11 deletions(-)
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;
}
diff --git a/slirp/mbuf.h b/slirp/mbuf.h
index 893601ff9d..33b84485d6 100644
--- a/slirp/mbuf.h
+++ b/slirp/mbuf.h
@@ -33,8 +33,6 @@
#ifndef MBUF_H
#define MBUF_H
-#define MINCSIZE 4096 /* Amount to increase mbuf if too small */
-
/*
* Macros for type conversion
* mtod(m,t) - convert mbuf pointer to data pointer of correct type
@@ -72,11 +70,11 @@ struct mbuf {
struct mbuf *m_prevpkt; /* Flags aren't used in the output
queue */
int m_flags; /* Misc flags */
- int m_size; /* Size of data */
+ int m_size; /* Size of mbuf, from m_dat or m_ext */
struct socket *m_so;
- caddr_t m_data; /* Location of data */
- int m_len; /* Amount of data in this mbuf */
+ caddr_t m_data; /* Current location of data */
+ int m_len; /* Amount of data in this mbuf, from
m_data */
Slirp *slirp;
bool resolution_requested;
--
2.17.1
- [Qemu-devel] [PULL 0/5] slirp updates, Samuel Thibault, 2018/06/08
- [Qemu-devel] [PULL 2/5] slirp: Add Samuel Thibault's staging tree for slirp, Samuel Thibault, 2018/06/08
- [Qemu-devel] [PULL 3/5] slirp: fix domainname version availability, Samuel Thibault, 2018/06/08
- [Qemu-devel] [PULL 4/5] slirp: correct size computation while concatenating mbuf,
Samuel Thibault <=
- [Qemu-devel] [PULL 5/5] slirp: reformat m_inc routine, Samuel Thibault, 2018/06/08
- [Qemu-devel] [PULL 1/5] slirp: Fix spurious error report when sending directly, Samuel Thibault, 2018/06/08
- Re: [Qemu-devel] [PULL 0/5] slirp updates, Peter Maydell, 2018/06/08
- Re: [Qemu-devel] [PULL 0/5] slirp updates, no-reply, 2018/06/08