misc: fastrpc: Fix double free of 'buf' in error path

smatch warning:
drivers/misc/fastrpc.c:1926 fastrpc_req_mmap() error: double free of 'buf'

In fastrpc_req_mmap() error path, the fastrpc buffer is freed in
fastrpc_req_munmap_impl() if unmap is successful.

But in the end, there is an unconditional call to fastrpc_buf_free().
So the above case triggers the double free of fastrpc buf.

Fixes: 72fa6f7820c4 ("misc: fastrpc: Rework fastrpc_req_munmap")
Reviewed-by: Shuah Khan <skhan@linuxfoundation.org>
Reviewed-by: Dan Carpenter <dan.carpenter@linaro.org>
Reviewed-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Sukrut Bellary <sukrut.bellary@linux.com>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Cc: stable <stable@kernel.org>
Link: https://lore.kernel.org/r/20240902141409.70371-2-srinivas.kandagatla@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/misc/fastrpc.c b/drivers/misc/fastrpc.c
index 339d126414d4bf842d08c593e15bd6a3954bbf38..da87abe93daf25d2e39b32241784f7aad414c803 100644 (file)
--- a/drivers/misc/fastrpc.c
+++ b/drivers/misc/fastrpc.c
@@ -1910,7 +1910,8 @@ static int fastrpc_req_mmap(struct fastrpc_user *fl, char __user *argp)
                                      &args[0]);
        if (err) {
                dev_err(dev, "mmap error (len 0x%08llx)\n", buf->size);
-               goto err_invoke;
+               fastrpc_buf_free(buf);
+               return err;
        }
 
        /* update the buffer to be able to deallocate the memory on the DSP */
@@ -1948,8 +1949,6 @@ static int fastrpc_req_mmap(struct fastrpc_user *fl, char __user *argp)
 
 err_assign:
        fastrpc_req_munmap_impl(fl, buf);
-err_invoke:
-       fastrpc_buf_free(buf);
 
        return err;
 }