diff options
| author | Udipto Goswami <quic_ugoswami@quicinc.com> | 2022-12-15 08:29:05 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-02-01 10:34:21 +0300 |
| commit | 6aee197b7fbcd61596a78b47d553f2f99111f217 (patch) | |
| tree | 75c04eb46a36731c57cc08005657482a6a73a7f7 /drivers | |
| parent | 3d7f77e55da3455c8844b651e37779c90e201f48 (diff) | |
| download | linux-6aee197b7fbcd61596a78b47d553f2f99111f217.tar.xz | |
usb: gadget: f_fs: Prevent race during ffs_ep0_queue_wait
[ Upstream commit 6a19da111057f69214b97c62fb0ac59023970850 ]
While performing fast composition switch, there is a possibility that the
process of ffs_ep0_write/ffs_ep0_read get into a race condition
due to ep0req being freed up from functionfs_unbind.
Consider the scenario that the ffs_ep0_write calls the ffs_ep0_queue_wait
by taking a lock &ffs->ev.waitq.lock. However, the functionfs_unbind isn't
bounded so it can go ahead and mark the ep0req to NULL, and since there
is no NULL check in ffs_ep0_queue_wait we will end up in use-after-free.
Fix this by making a serialized execution between the two functions using
a mutex_lock(ffs->mutex).
Fixes: ddf8abd25994 ("USB: f_fs: the FunctionFS driver")
Signed-off-by: Udipto Goswami <quic_ugoswami@quicinc.com>
Tested-by: Krishna Kurapati <quic_kriskura@quicinc.com>
Link: https://lore.kernel.org/r/20221215052906.8993-2-quic_ugoswami@quicinc.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/usb/gadget/function/f_fs.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/drivers/usb/gadget/function/f_fs.c b/drivers/usb/gadget/function/f_fs.c index 73dc10a77cde..bb6fe1f3a29d 100644 --- a/drivers/usb/gadget/function/f_fs.c +++ b/drivers/usb/gadget/function/f_fs.c @@ -279,6 +279,9 @@ static int __ffs_ep0_queue_wait(struct ffs_data *ffs, char *data, size_t len) struct usb_request *req = ffs->ep0req; int ret; + if (!req) + return -EINVAL; + req->zero = len < le16_to_cpu(ffs->ev.setup.wLength); spin_unlock_irq(&ffs->ev.waitq.lock); @@ -1892,10 +1895,12 @@ static void functionfs_unbind(struct ffs_data *ffs) ENTER(); if (!WARN_ON(!ffs->gadget)) { + mutex_lock(&ffs->mutex); usb_ep_free_request(ffs->gadget->ep0, ffs->ep0req); ffs->ep0req = NULL; ffs->gadget = NULL; clear_bit(FFS_FL_BOUND, &ffs->flags); + mutex_unlock(&ffs->mutex); ffs_data_put(ffs); } } |