udmabuf: also check for F_SEAL_FUTURE_WRITE

When F_SEAL_FUTURE_WRITE was introduced, it was overlooked that udmabuf
must reject memfds with this flag, just like ones with F_SEAL_WRITE.
Fix it by adding F_SEAL_FUTURE_WRITE to SEALS_DENIED.

Fixes: ab3948f ("mm/memfd: add an F_SEAL_FUTURE_WRITE seal to memfd")
Cc: stable@vger.kernel.org
Acked-by: Vivek Kasireddy <vivek.kasireddy@intel.com>
Signed-off-by: Jann Horn <jannh@google.com>
Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Vivek Kasireddy <vivek.kasireddy@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241204-udmabuf-fixes-v2-2-23887289de1c@google.com

Author: thejh

drivers/dma-buf/udmabuf.c

@@ -297,7 +297,7 @@ static const struct dma_buf_ops udmabuf_ops = {
 };
 
 #define SEALS_WANTED (F_SEAL_SHRINK)
-#define SEALS_DENIED (F_SEAL_WRITE)
+#define SEALS_DENIED (F_SEAL_WRITE|F_SEAL_FUTURE_WRITE)
 
 static int check_memfd_seals(struct file *memfd)
 {