From e002e92e88e12457373ed096b18716d97e7bbb20 Mon Sep 17 00:00:00 2001 From: Kuen-Han Tsai Date: Mon, 16 Mar 2026 15:49:09 +0800 Subject: [PATCH] usb: gadget: u_ether: Fix NULL pointer deref in eth_get_drvinfo Commit ec35c1969650 ("usb: gadget: f_ncm: Fix net_device lifecycle with device_move") reparents the gadget device to /sys/devices/virtual during unbind, clearing the gadget pointer. If the userspace tool queries on the surviving interface during this detached window, this leads to a NULL pointer dereference. Unable to handle kernel NULL pointer dereference Call trace: eth_get_drvinfo+0x50/0x90 ethtool_get_drvinfo+0x5c/0x1f0 __dev_ethtool+0xaec/0x1fe0 dev_ethtool+0x134/0x2e0 dev_ioctl+0x338/0x560 Add a NULL check for dev->gadget in eth_get_drvinfo(). When detached, skip copying the fw_version and bus_info strings, which is natively handled by ethtool_get_drvinfo for empty strings. Suggested-by: Val Packett Reported-by: Val Packett Closes: https://lore.kernel.org/linux-usb/10890524-cf83-4a71-b879-93e2b2cc1fcc@packett.cool/ Fixes: ec35c1969650 ("usb: gadget: f_ncm: Fix net_device lifecycle with device_move") Cc: stable Signed-off-by: Kuen-Han Tsai Link: https://patch.msgid.link/20260316-eth-null-deref-v1-1-07005f33be85@google.com Signed-off-by: Greg Kroah-Hartman --- drivers/usb/gadget/function/u_ether.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/drivers/usb/gadget/function/u_ether.c b/drivers/usb/gadget/function/u_ether.c index 23c7c0cdf202..59d85d6a84a8 100644 --- a/drivers/usb/gadget/function/u_ether.c +++ b/drivers/usb/gadget/function/u_ether.c @@ -113,8 +113,10 @@ static void eth_get_drvinfo(struct net_device *net, struct ethtool_drvinfo *p) strscpy(p->driver, "g_ether", sizeof(p->driver)); strscpy(p->version, UETH__VERSION, sizeof(p->version)); - strscpy(p->fw_version, dev->gadget->name, sizeof(p->fw_version)); - strscpy(p->bus_info, dev_name(&dev->gadget->dev), sizeof(p->bus_info)); + if (dev->gadget) { + strscpy(p->fw_version, dev->gadget->name, sizeof(p->fw_version)); + strscpy(p->bus_info, dev_name(&dev->gadget->dev), sizeof(p->bus_info)); + } } /* REVISIT can also support: