From: Udipto Goswami <quic_ugoswami@quicinc.com> stable inclusion from stable-v4.19.272 commit e9036e951f93fb8d7b5e9d6e2c7f94a4da312ae4 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IBWVWG CVE: CVE-2022-49755 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- [ 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> Signed-off-by: Guo Mengqi <guomengqi3@huawei.com> --- drivers/usb/gadget/function/f_fs.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/drivers/usb/gadget/function/f_fs.c b/drivers/usb/gadget/function/f_fs.c index 4ec3f27a0aea..5c1d797b5bcb 100644 --- a/drivers/usb/gadget/function/f_fs.c +++ b/drivers/usb/gadget/function/f_fs.c @@ -271,6 +271,9 @@ 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); @@ -1807,10 +1810,12 @@ 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); } } -- 2.22.0