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a=ed25519-sha256; t=1773647436; l=2135; i=khtsai@google.com; s=20250916; h=from:subject:message-id; bh=/RWe9PyCUXFRwSCWlayNd4QMbnC9+kpyi17Lalv4lm0=; b=TgvUJBTeQcaDr54lNumTEgp8wSLlfl1c9X6UN/k1ZUamWhUv2Q94uGWTtLUrpmRYWmAL3NAbc ba/BxZL7Q9zD97ejcNwbhb/hXgfH0+e6H2t1WQ4aGX70cyaCYZ4bZIv X-Mailer: b4 0.14.3 Message-ID: <20260316-eth-null-deref-v1-1-07005f33be85@google.com> Subject: [PATCH] usb: gadget: u_ether: Fix NULL pointer deref in eth_get_drvinfo From: Kuen-Han Tsai To: Greg Kroah-Hartman Cc: David Heidelberg , Val Packett , linux-usb@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, Kuen-Han Tsai Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable 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-b879-93e2b2cc1= fcc@packett.cool/ Fixes: ec35c1969650 ("usb: gadget: f_ncm: Fix net_device lifecycle with dev= ice_move") Cc: stable@vger.kernel.org Signed-off-by: Kuen-Han Tsai Tested-by: Aelin Reidel Tested-by: David Heidelberg --- 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/fun= ction/u_ether.c index 1a9e7c495e2e..a653fae9c0cb 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, st= ruct ethtool_drvinfo *p) =20 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)); + } } =20 /* REVISIT can also support: --- base-commit: d0d9b1f4f5391e6a00cee81d73ed2e8f98446d5f change-id: 20260316-eth-null-deref-0304bb048267 Best regards, --=20 Kuen-Han Tsai