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 Acked-by: Scott Branden scott.branden@broadcom.com Signed-off-by: Kees Cook keescook@chromium.org --- To aid in backporting, this change is made before moving kernel_read_file() to separate header/source files. --- 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;