[PATCH 1/4] firmware_loader: EFI firmware loader must handle pre-allocated buffer

Kees Cook
2020-07-07T08:19:45Z

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 firm ware_request_platform()")
Cc: stable@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
---
drivers/base/firmware_loader/fallback_platform.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/base/firmware_loader/fallback_platform.c b/drivers/base/firmware_loader/fallback_platform.c
index cdd2c9a9f38a..685edb7dd05a 100644
--- 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_priv *fw_priv, u32 opt_flags)
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;

--
2.25.1