From 8a0200d14acd9db388b85cd016e68a4e60d900ec Mon Sep 17 00:00:00 2001 From: Syed Labeeq Sajid Bukhari Date: Thu, 10 Sep 2026 19:03:43 +0500 Subject: usb: storage: sierra_ms: reject short SWoC info transfers sierra_get_swoc_info() requests sizeof(struct swoc_info) (60) bytes from the device via usb_control_msg(), but its callers only treat a negative return value as failure. A device that answers the vendor-specific GetSwocInfo request with a short IN transfer is therefore accepted, leaving the tail of the freshly allocated (kmalloc(), non-zeroing) swoc_info buffer uninitialized. truinst_show() subsequently prints swocInfo->rev, swocInfo->LinuxSKU and swocInfo->LinuxVer from that buffer into the world-readable (0444) "truinst" sysfs attribute. An emulated/malicious USB device (VID 0x1199, PID 0x0fff) can exploit this to disclose up to 5 bytes of stale kernel heap memory (kmalloc-64) to unprivileged userspace, once per sysfs read, indefinitely. On kernels built without init_on_alloc this leaks recently freed heap contents. Only accept the transfer when the full structure was received. sierra_ms_init() already retries failed queries, so well-behaved devices are unaffected. Fixes: 32fe5e393455 ("USB Storage Sierra: TRU-Install feature update") Cc: stable Signed-off-by: Syed Labeeq Sajid Bukhari Assisted-by: Kimi:K2 [Kimi Code CLI] Link: https://patch.msgid.link/20260910140343.49371-1-syedlabeeq@gmail.com Signed-off-by: Greg Kroah-Hartman --- drivers/usb/storage/sierra_ms.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/drivers/usb/storage/sierra_ms.c b/drivers/usb/storage/sierra_ms.c index c5e3eeeb2144..992685ca6f1a 100644 --- a/drivers/usb/storage/sierra_ms.c +++ b/drivers/usb/storage/sierra_ms.c @@ -77,6 +77,13 @@ static int sierra_get_swoc_info(struct usb_device *udev, sizeof(struct swoc_info), /* __u16 size */ USB_CTRL_SET_TIMEOUT); /* int timeout */ + /* + * A short IN transfer leaves the tail of swocInfo uninitialized; + * only a full transfer is valid. + */ + if (result != sizeof(struct swoc_info)) + return -EIO; + swocInfo->LinuxSKU = le16_to_cpu(swocInfo->LinuxSKU); swocInfo->LinuxVer = le16_to_cpu(swocInfo->LinuxVer); return result; -- cgit v1.2.3