This is a note to let you know that I've just added the patch titled

usb: hub: Guard against accesses to uninitialized BOS descriptors

to my usb git tree which can be found at git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb.git in the usb-linus branch.

The patch will show up in the next release of the linux-next tree (usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the next -rc kernel release.

If you have any questions about this process, please let me know.

From f74a7afc224acd5e922c7a2e52244d891bbe44ee Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Ricardo=20Ca=C3=B1uelo?= ricardo.canuelo@collabora.com Date: Wed, 30 Aug 2023 12:04:18 +0200 Subject: usb: hub: Guard against accesses to uninitialized BOS descriptors MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit

Many functions in drivers/usb/core/hub.c and drivers/usb/core/hub.h access fields inside udev->bos without checking if it was allocated and initialized. If usb_get_bos_descriptor() fails for whatever reason, udev->bos will be NULL and those accesses will result in a crash:

BUG: kernel NULL pointer dereference, address: 0000000000000018 PGD 0 P4D 0 Oops: 0000 [#1] PREEMPT SMP NOPTI CPU: 5 PID: 17818 Comm: kworker/5:1 Tainted: G W 5.15.108-18910-gab0e1cb584e1 #1 <HASH:1f9e 1> Hardware name: Google Kindred/Kindred, BIOS Google_Kindred.12672.413.0 02/03/2021 Workqueue: usb_hub_wq hub_event RIP: 0010:hub_port_reset+0x193/0x788 Code: 89 f7 e8 20 f7 15 00 48 8b 43 08 80 b8 96 03 00 00 03 75 36 0f b7 88 92 03 00 00 81 f9 10 03 00 00 72 27 48 8b 80 a8 03 00 00 <48> 83 78 18 00 74 19 48 89 df 48 8b 75 b0 ba 02 00 00 00 4c 89 e9 RSP: 0018:ffffab740c53fcf8 EFLAGS: 00010246 RAX: 0000000000000000 RBX: ffffa1bc5f678000 RCX: 0000000000000310 RDX: fffffffffffffdff RSI: 0000000000000286 RDI: ffffa1be9655b840 RBP: ffffab740c53fd70 R08: 00001b7d5edaa20c R09: ffffffffb005e060 R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000000 R13: ffffab740c53fd3e R14: 0000000000000032 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffffa1be96540000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000018 CR3: 000000022e80c005 CR4: 00000000003706e0 Call Trace: hub_event+0x73f/0x156e ? hub_activate+0x5b7/0x68f process_one_work+0x1a2/0x487 worker_thread+0x11a/0x288 kthread+0x13a/0x152 ? process_one_work+0x487/0x487 ? kthread_associate_blkcg+0x70/0x70 ret_from_fork+0x1f/0x30

Fall back to a default behavior if the BOS descriptor isn't accessible and skip all the functionalities that depend on it: LPM support checks, Super Speed capabilitiy checks, U1/U2 states setup.

Signed-off-by: Ricardo Cañuelo ricardo.canuelo@collabora.com Cc: stable stable@vger.kernel.org Link: https://lore.kernel.org/r/20230830100418.1952143-1-ricardo.canuelo@collabora... Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/usb/core/hub.c | 25 ++++++++++++++++++++++--- drivers/usb/core/hub.h | 2 +- 2 files changed, 23 insertions(+), 4 deletions(-)

diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c index 3c54b218301c..0ff47eeffb49 100644 --- a/drivers/usb/core/hub.c +++ b/drivers/usb/core/hub.c @@ -151,6 +151,10 @@ int usb_device_supports_lpm(struct usb_device *udev) if (udev->quirks & USB_QUIRK_NO_LPM) return 0;

+ /* Skip if the device BOS descriptor couldn't be read */ + if (!udev->bos) + return 0; + /* USB 2.1 (and greater) devices indicate LPM support through * their USB 2.0 Extended Capabilities BOS descriptor. */ @@ -327,6 +331,10 @@ static void usb_set_lpm_parameters(struct usb_device *udev) if (!udev->lpm_capable || udev->speed < USB_SPEED_SUPER) return;

+ /* Skip if the device BOS descriptor couldn't be read */ + if (!udev->bos) + return; + hub = usb_hub_to_struct_hub(udev->parent); /* It doesn't take time to transition the roothub into U0, since it * doesn't have an upstream link. @@ -2704,13 +2712,17 @@ int usb_authorize_device(struct usb_device *usb_dev) static enum usb_ssp_rate get_port_ssp_rate(struct usb_device *hdev, u32 ext_portstatus) { - struct usb_ssp_cap_descriptor *ssp_cap = hdev->bos->ssp_cap; + struct usb_ssp_cap_descriptor *ssp_cap; u32 attr; u8 speed_id; u8 ssac; u8 lanes; int i;

+ if (!hdev->bos) + goto out; + + ssp_cap = hdev->bos->ssp_cap; if (!ssp_cap) goto out;

@@ -4215,8 +4227,15 @@ static void usb_enable_link_state(struct usb_hcd *hcd, struct usb_device *udev, enum usb3_link_state state) { int timeout; - __u8 u1_mel = udev->bos->ss_cap->bU1devExitLat; - __le16 u2_mel = udev->bos->ss_cap->bU2DevExitLat; + __u8 u1_mel; + __le16 u2_mel; + + /* Skip if the device BOS descriptor couldn't be read */ + if (!udev->bos) + return; + + u1_mel = udev->bos->ss_cap->bU1devExitLat; + u2_mel = udev->bos->ss_cap->bU2DevExitLat;

/* If the device says it doesn't have *any* exit latency to come out of * U1 or U2, it's probably lying. Assume it doesn't implement that link diff --git a/drivers/usb/core/hub.h b/drivers/usb/core/hub.h index 37897afd1b64..d44dd7f6623e 100644 --- a/drivers/usb/core/hub.h +++ b/drivers/usb/core/hub.h @@ -153,7 +153,7 @@ static inline int hub_is_superspeedplus(struct usb_device *hdev) { return (hdev->descriptor.bDeviceProtocol == USB_HUB_PR_SS && le16_to_cpu(hdev->descriptor.bcdUSB) >= 0x0310 && - hdev->bos->ssp_cap); + hdev->bos && hdev->bos->ssp_cap); }

static inline unsigned hub_power_on_good_delay(struct usb_hub *hub)