From affdf476543405045c281a7c67d1eaedbcea8135 Mon Sep 17 00:00:00 2001 From: Jason Wang 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 Reported-by: Cheolwoo Myung Reported-by: Ruhr-University Bochum Cc: Prasad J Pandit Cc: qemu-stable@nongnu.org Signed-off-by: Jason Wang Upstream-Status: Backport [3de46e6fc489c52c9431a8a832ad8170a7569bd8] CVE: CVE-2021-20257 Signed-off-by: Sakib Sajal --- 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