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From affdf476543405045c281a7c67d1eaedbcea8135 Mon Sep 17 00:00:00 2001
From: Jason Wang <jasowang@redhat.com>
Date: Wed, 24 Feb 2021 13:45:28 +0800
Subject: [PATCH] e1000: fail early for evil descriptor
During procss_tx_desc(), driver can try to chain data descriptor with
legacy descriptor, when will lead underflow for the following
calculation in process_tx_desc() for bytes:
if (tp->size + bytes > msh)
bytes = msh - tp->size;
This will lead a infinite loop. So check and fail early if tp->size if
greater or equal to msh.
Reported-by: Alexander Bulekov <alxndr@bu.edu>
Reported-by: Cheolwoo Myung <cwmyung@snu.ac.kr>
Reported-by: Ruhr-University Bochum <bugs-syssec@rub.de>
Cc: Prasad J Pandit <ppandit@redhat.com>
Cc: qemu-stable@nongnu.org
Signed-off-by: Jason Wang <jasowang@redhat.com>
Upstream-Status: Backport [3de46e6fc489c52c9431a8a832ad8170a7569bd8]
CVE: CVE-2021-20257
Signed-off-by: Sakib Sajal <sakib.sajal@windriver.com>
---
hw/net/e1000.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/hw/net/e1000.c b/hw/net/e1000.c
index cf22c4f07..c3564c7ce 100644
--- a/hw/net/e1000.c
+++ b/hw/net/e1000.c
@@ -670,6 +670,9 @@ process_tx_desc(E1000State *s, struct e1000_tx_desc *dp)
msh = tp->tso_props.hdr_len + tp->tso_props.mss;
do {
bytes = split_size;
+ if (tp->size >= msh) {
+ goto eop;
+ }
if (tp->size + bytes > msh)
bytes = msh - tp->size;
@@ -695,6 +698,7 @@ process_tx_desc(E1000State *s, struct e1000_tx_desc *dp)
tp->size += split_size;
}
+eop:
if (!(txd_lower & E1000_TXD_CMD_EOP))
return;
if (!(tp->cptse && tp->size < tp->tso_props.hdr_len)) {
--
2.29.2
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