--- /dev/null
+From 4fb60b158afd3ac9e0fe9975aa476213f5cc0a4d Mon Sep 17 00:00:00 2001
+From: Kees Cook <keescook@chromium.org>
+Date: Fri, 24 Jul 2020 14:36:24 -0700
+Subject: firmware_loader: EFI firmware loader must handle pre-allocated buffer
+
+From: Kees Cook <keescook@chromium.org>
+
+commit 4fb60b158afd3ac9e0fe9975aa476213f5cc0a4d upstream.
+
+The EFI platform firmware fallback would clobber any pre-allocated
+buffers. Instead, correctly refuse to reallocate when too small (as
+already done in the sysfs fallback), or perform allocation normally
+when needed.
+
+Fixes: e4c2c0ff00ec ("firmware: Add new platform fallback mechanism and firmware_request_platform()")
+Cc: stable@vger.kernel.org
+Acked-by: Scott Branden <scott.branden@broadcom.com>
+Signed-off-by: Kees Cook <keescook@chromium.org>
+Link: https://lore.kernel.org/r/20200724213640.389191-4-keescook@chromium.org
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ drivers/base/firmware_loader/fallback_platform.c | 5 ++++-
+ 1 file changed, 4 insertions(+), 1 deletion(-)
+
+--- a/drivers/base/firmware_loader/fallback_platform.c
++++ b/drivers/base/firmware_loader/fallback_platform.c
+@@ -25,7 +25,10 @@ int firmware_fallback_platform(struct fw
+ if (rc)
+ return rc; /* rc == -ENOENT when the fw was not found */
+
+- fw_priv->data = vmalloc(size);
++ if (fw_priv->data && size > fw_priv->allocated_size)
++ return -ENOMEM;
++ if (!fw_priv->data)
++ fw_priv->data = vmalloc(size);
+ if (!fw_priv->data)
+ return -ENOMEM;
+