From e563bc3dcd17d91861d3b363ed19d30228f409e1 Mon Sep 17 00:00:00 2001 From: Javier Martinez Canillas Date: Fri, 7 Sep 2018 15:10:51 +0200 Subject: [PATCH] shim: Prevent shim to set itself as a second stage loader When shim is invoked from a relative path (e.g: from the UEFI shell), the Loaded Image handle LoadOptions can be set to the binary relative path. But the is_our_path() function only checks if LoadOptions is set to the absolute path of shim to ignore it. So if a relative path is there, shim would set itself as the secondary loader and invoke itself in a loop. To prevent that, use the path in LoadOptions to calculate the absolute path and compare it with the one in the Loader Image handle FilePath. Resolves: bz#1622485 Signed-off-by: Javier Martinez Canillas Reviewed-by: Maran Wilson maran.wilson@oracle.com Tested-by: Maran Wilson maran.wilson@oracle.com --- shim.c | 17 ++++++++++++++--- 1 file changed, 14 insertions(+), 3 deletions(-) diff --git a/shim.c b/shim.c index 32d2772b279..8abc0c267cf 100644 --- a/shim.c +++ b/shim.c @@ -2116,21 +2116,32 @@ get_load_option_optional_data(UINT8 *data, UINTN data_size, return EFI_SUCCESS; } -static int is_our_path(EFI_LOADED_IMAGE *li, CHAR16 *path, UINTN len) +static int is_our_path(EFI_LOADED_IMAGE *li, CHAR16 *path) { CHAR16 *dppath = NULL; + CHAR16 *PathName = NULL; + EFI_STATUS efi_status; int ret = 1; dppath = DevicePathToStr(li->FilePath); if (!dppath) return 0; + efi_status = generate_path_from_image_path(li, path, &PathName); + if (EFI_ERROR(efi_status)) { + perror(L"Unable to generate path %s: %r\n", path, + efi_status); + goto done; + } + dprint(L"dppath: %s\n", dppath); dprint(L"path: %s\n", path); - if (StrnCaseCmp(dppath, path, len)) + if (StrnCaseCmp(dppath, PathName, strlen(dppath))) ret = 0; +done: FreePool(dppath); + FreePool(PathName); return ret; } @@ -2319,7 +2330,7 @@ EFI_STATUS set_second_stage (EFI_HANDLE image_handle) * which is just cruel... So yeah, just don't use it. */ - if (strings == 1 && is_our_path(li, start, loader_len)) + if (strings == 1 && is_our_path(li, start)) return EFI_SUCCESS; /* -- 2.21.0