fastrpc_req_munmap involves two steps to unmap memory, first to locates a matching fastrpc buf in the list and second is to send request to DSP to unmap. There is a potential race condition between two operations which can lead to user-after-free scenario. Lock unmap request to avoid use-after-free. Signed-off-by: Ling Xu <quic_lxu5@xxxxxxxxxxx> --- drivers/misc/fastrpc.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c index 7b7a22c91fe4..9ad092d3a705 100644 --- a/drivers/misc/fastrpc.c +++ b/drivers/misc/fastrpc.c @@ -2117,7 +2117,9 @@ 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); break; case FASTRPC_IOCTL_MEM_MAP: err = fastrpc_req_mem_map(fl, argp); -- 2.34.1
