> Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> writes: > Who is the original author here? Please put their name as the "From:" > line in the changelog so we can give proper credit if it was not you. Phil Elwell. Fixed. > Test for !req and then abort, and then continue on. No need for moving > the copy_from_user line in, right? Should make the change smaller > overall. Fixed. > Blank line after this please. Added. > Are the braces still needed here? No, you're right. Thanks for the review! Here the new version of the patch: >From 72a504af8e3df3d7a44e9954b8cf03268795c07f Mon Sep 17 00:00:00 2001 From: Phil Elwell <phil@xxxxxxxxxxxxxxx> Date: Fri, 23 Jul 2021 11:59:49 +0300 Subject: [PATCH] usb: gadget: f_hid: fixed NULL pointer dereference Disconnecting and reconnecting the USB cable can lead to crashes and a variety of kernel log spam. The problem was found and reproduced on the Raspberry Pi [1] and the original fix was created in Raspberry's own fork [2]. Signed-off-by: Maxim Devaev <mdevaev@xxxxxxxxx> Signed-off-by: Phil Elwell <phil@xxxxxxxxxxxxxxx> Link: https://github.com/raspberrypi/linux/issues/3870 [1] Link: https://github.com/raspberrypi/linux/commit/a6e47d5f4efbd2ea6a0b6565cd2f9b7bb217ded5 [2] --- drivers/usb/gadget/function/f_hid.c | 26 ++++++++++++++++++++------ 1 file changed, 20 insertions(+), 6 deletions(-) diff --git a/drivers/usb/gadget/function/f_hid.c b/drivers/usb/gadget/function/f_hid.c index 02683ac07..08e73e812 100644 --- a/drivers/usb/gadget/function/f_hid.c +++ b/drivers/usb/gadget/function/f_hid.c @@ -338,6 +338,11 @@ static ssize_t f_hidg_write(struct file *file, const char __user *buffer, spin_lock_irqsave(&hidg->write_spinlock, flags); + if (!hidg->req) { + spin_unlock_irqrestore(&hidg->write_spinlock, flags); + return -ESHUTDOWN; + } + #define WRITE_COND (!hidg->write_pending) try_again: /* write queue */ @@ -358,8 +363,14 @@ static ssize_t f_hidg_write(struct file *file, const char __user *buffer, count = min_t(unsigned, count, hidg->report_length); spin_unlock_irqrestore(&hidg->write_spinlock, flags); - status = copy_from_user(req->buf, buffer, count); + if (!req) { + ERROR(hidg->func.config->cdev, "hidg->req is NULL\n"); + status = -ESHUTDOWN; + goto release_write_pending; + } + + status = copy_from_user(req->buf, buffer, count); if (status != 0) { ERROR(hidg->func.config->cdev, "copy_from_user error\n"); @@ -387,14 +398,17 @@ static ssize_t f_hidg_write(struct file *file, const char __user *buffer, spin_unlock_irqrestore(&hidg->write_spinlock, flags); + if (!hidg->in_ep->enabled) { + ERROR(hidg->func.config->cdev, "in_ep is disabled\n"); + status = -ESHUTDOWN; + goto release_write_pending; + } + status = usb_ep_queue(hidg->in_ep, req, GFP_ATOMIC); - if (status < 0) { - ERROR(hidg->func.config->cdev, - "usb_ep_queue error on int endpoint %zd\n", status); + if (status < 0) goto release_write_pending; - } else { + else status = count; - } return status; release_write_pending: -- 2.32.0
