Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [PATCH 4.19 03/39] usb: gadget: f_fs: Use local copy of descriptors for userspace copy | Date | Thu, 10 Dec 2020 15:26:42 +0100 |
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From: Vamsi Krishna Samavedam <vskrishn@codeaurora.org>
commit a4b98a7512f18534ce33a7e98e49115af59ffa00 upstream.
The function may be unbound causing the ffs_ep and its descriptors to be freed while userspace is in the middle of an ioctl requesting the same descriptors. Avoid dangling pointer reference by first making a local copy of desctiptors before releasing the spinlock.
Fixes: c559a3534109 ("usb: gadget: f_fs: add ioctl returning ep descriptor") Reviewed-by: Peter Chen <peter.chen@nxp.com> Signed-off-by: Vamsi Krishna Samavedam <vskrishn@codeaurora.org> Signed-off-by: Jack Pham <jackp@codeaurora.org> Cc: stable <stable@vger.kernel.org> Link: https://lore.kernel.org/r/20201130203453.28154-1-jackp@codeaurora.org Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- drivers/usb/gadget/function/f_fs.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
--- a/drivers/usb/gadget/function/f_fs.c +++ b/drivers/usb/gadget/function/f_fs.c @@ -1243,7 +1243,7 @@ static long ffs_epfile_ioctl(struct file case FUNCTIONFS_ENDPOINT_DESC: { int desc_idx; - struct usb_endpoint_descriptor *desc; + struct usb_endpoint_descriptor desc1, *desc; switch (epfile->ffs->gadget->speed) { case USB_SPEED_SUPER: @@ -1255,10 +1255,12 @@ static long ffs_epfile_ioctl(struct file default: desc_idx = 0; } + desc = epfile->ep->descs[desc_idx]; + memcpy(&desc1, desc, desc->bLength); spin_unlock_irq(&epfile->ffs->eps_lock); - ret = copy_to_user((void __user *)value, desc, desc->bLength); + ret = copy_to_user((void __user *)value, &desc1, desc1.bLength); if (ret) ret = -EFAULT; return ret;
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