From 106e562966a02f61917c2e0b83909aa2b088447f Mon Sep 17 00:00:00 2001 From: Anirudh Virdi Date: Tue, 13 Oct 2026 16:24:51 +0530 Subject: [PATCH] net: qede: initialize extack in qede_flow_spec_to_rule() MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit qede_flow_spec_to_rule() declares a netlink_ext_ack on the stack without initializing it. qede_parse_flow_attr() and qede_flow_spec_validate() only set extack._msg on error paths via NL_SET_ERR_MSG_MOD(), so on a successful parse the err_out block reads an uninitialized pointer. If that garbage happens to be non-NULL, DP_NOTICE("%s", extack._msg) dereferences it inside vsnprintf, causing a page fault and kernel panic. This manifests when configuring ethtool ntuple flow rules (ethtool -U flow-type tcp4/udp4) on kernels built with CONFIG_INIT_STACK_NONE=y. With CONFIG_INIT_STACK_ALL_ZERO=y the bug is masked because the compiler zero-initializes extack, making _msg NULL. Reproduced on RHEL 9.8 (kernel-5.14.0-687.47.1.el9_8) and mainline (v7.3-rc6) with the following reproducer: IFACE=ens2f0 ip link set $IFACE up ethtool -K $IFACE ntuple on for i in $(seq 1 100); do ethtool -U $IFACE flow-type udp4 src-ip 192.168.2.$i action -1 done The loop panics reliably after 10-15 iterations with: BUG: unable to handle page fault RIP: string+0x49/0xd0 Call Trace: vsnprintf qede_flow_spec_to_rule+0x2b6/0x4b0 [qede] qede_add_cls_rule ethtool_set_rxnfc Zero-initialize extack so _msg is NULL unless explicitly set by an error path. Fixes: eb705d734525 ("net: qede: use faked extack in qede_flow_spec_to_rule()") Signed-off-by: Anirudh Virdi Reviewed-by: Asbjørn Sloth Tønnesen Reviewed-by: Daniel Machon Link: https://patch.msgid.link/20261013105451.201211-1-avirdi@redhat.com Signed-off-by: Jakub Kicinski --- drivers/net/ethernet/qlogic/qede/qede_filter.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/net/ethernet/qlogic/qede/qede_filter.c b/drivers/net/ethernet/qlogic/qede/qede_filter.c index ab8b818588e2..5bf32f1034e0 100644 --- a/drivers/net/ethernet/qlogic/qede/qede_filter.c +++ b/drivers/net/ethernet/qlogic/qede/qede_filter.c @@ -1991,8 +1991,8 @@ static int qede_flow_spec_to_rule(struct qede_dev *edev, struct ethtool_rx_flow_spec *fs) { struct ethtool_rx_flow_spec_input input = {}; + struct netlink_ext_ack extack = {}; struct ethtool_rx_flow_rule *flow; - struct netlink_ext_ack extack; __be16 proto; int err;