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From: Mauro Matteo Cascella <mcascell@redhat.com>
To: qemu-devel@nongnu.org
Cc: alxndr@bu.edu, jasowang@redhat.com, dmitry.fleytman@gmail.com,
	mcascell@redhat.com, ezrakiez@gmail.com
Subject: [PATCH v2] hw/net/net_tx_pkt: fix assertion failure in net_tx_pkt_add_raw_fragment()
Date: Sat,  1 Aug 2020 18:42:38 +0200
Message-ID: <20200801164238.1610609-1-mcascell@redhat.com> (raw)

An assertion failure issue was found in the code that processes network packets
while adding data fragments into the packet context. It could be abused by a
malicious guest to abort the QEMU process on the host. This patch replaces the
affected assert() with a conditional statement, returning false if the current
data fragment exceeds max_raw_frags.

Reported-by: Alexander Bulekov <alxndr@bu.edu>
Reported-by: Ziming Zhang <ezrakiez@gmail.com>
Signed-off-by: Mauro Matteo Cascella <mcascell@redhat.com>
---
 hw/net/net_tx_pkt.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/hw/net/net_tx_pkt.c b/hw/net/net_tx_pkt.c
index 9560e4a49e..da262edc3e 100644
--- a/hw/net/net_tx_pkt.c
+++ b/hw/net/net_tx_pkt.c
@@ -379,7 +379,10 @@ bool net_tx_pkt_add_raw_fragment(struct NetTxPkt *pkt, hwaddr pa,
     hwaddr mapped_len = 0;
     struct iovec *ventry;
     assert(pkt);
-    assert(pkt->max_raw_frags > pkt->raw_frags);
+
+    if (pkt->raw_frags >= pkt->max_raw_frags) {
+        return false;
+    }
 
     if (!len) {
         return true;
-- 
2.26.2



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Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-01 16:42 Mauro Matteo Cascella [this message]
2020-08-02 14:43 ` Dmitry Fleytman
2020-08-04  6:01 ` Jason Wang

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