On Thu, Apr 27, 2023 at 06:29:16PM +0900, sangsup lee wrote: > Is there any comment for this issue? What issue? > (reference: https://www.spinics.net/lists/kernel/msg4731408.html) Please use lore.kernel.org links, we have no control over any other random email archive . And the above link just points to this proposed patch. > > > 2023년 3월 23일 (목) 오전 10:37, Sangsup Lee <k1rh4.lee@xxxxxxxxx>님이 작성: > > > > From: Sangsup lee <k1rh4.lee@xxxxxxxxx> > > > > This patch adds mutex_lock for fixing an Use-after-free bug. > > fastrpc_req_munmap_impl can be called concurrently in multi-threded environments. > > The buf which is allocated by list_for_each_safe can be used after another thread frees it. How was this tested? > > > > Signed-off-by: Sangsup lee <k1rh4.lee@xxxxxxxxx> > > --- > > V1 -> V2: moving the locking to ioctl. > > > > drivers/misc/fastrpc.c | 2 ++ > > 1 file changed, 2 insertions(+) > > > > diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c > > index 93ebd174d848..aa1cf0e9f4ed 100644 > > --- a/drivers/misc/fastrpc.c > > +++ b/drivers/misc/fastrpc.c > > @@ -1901,7 +1901,9 @@ static long fastrpc_device_ioctl(struct file *file, unsigned int cmd, > > err = fastrpc_req_mmap(fl, argp); > > break; > > case FASTRPC_IOCTL_MUNMAP: > > + mutex_lock(&fl->mutex); > > err = fastrpc_req_munmap(fl, argp); > > + mutex_unlock(&fl->mutex); Are you sure you can call this function with the lock? If so, why isn't the mmap ioctl also locked? thanks, greg k-h
