From ac610fe45491deccaab2c4ee689cbbdac117930a Mon Sep 17 00:00:00 2001 From: Javier Martinez Canillas Date: Tue, 8 Sep 2020 12:26:45 +0200 Subject: [PATCH] Fix buffer overrun due DEFAULT_LOADER length miscalculation The DEFAULT_LOADER is a UCS-2 string and the StrLen() function returns the number of UCS-2 encoded characters in the string. But the allocated memory is in bytes, so only half of the needed memory to store it is allocated. This leads to a buffer overrun when the StrCpy() function attempts to copy the DEFAULT_LOADER to the allocated buffer. Fixes: 354bd9b1931 ("Actually check for errors from set_second_stage()") Reported-by: Stuart Hayes Signed-off-by: Javier Martinez Canillas --- shim.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/shim.c b/shim.c index 34dce25c330..82913c934f6 100644 --- a/shim.c +++ b/shim.c @@ -2096,8 +2096,9 @@ EFI_STATUS set_second_stage (EFI_HANDLE image_handle) unsigned int i; UINTN second_stage_len; - second_stage_len = StrLen(DEFAULT_LOADER) + 1; + second_stage_len = (StrLen(DEFAULT_LOADER) + 1) * sizeof(CHAR16); second_stage = AllocatePool(second_stage_len); + if (!second_stage) { perror(L"Could not allocate %lu bytes\n", second_stage_len); return EFI_OUT_OF_RESOURCES; -- 2.28.0