diff options
| author | Michael Brown <mcb30@ipxe.org> | 2020-07-09 14:20:53 +0100 |
|---|---|---|
| committer | Michael Brown <mcb30@ipxe.org> | 2020-07-09 14:20:53 +0100 |
| commit | b6eecb182e07a82bae2a5f8c28dadb1bea409090 (patch) | |
| tree | 366c1f338fc6d51c921b5a095a8c5d82fa4e5c8d | |
| parent | fcdd9c0982e6c5a435fefdcc9444242fd4fbdd8b (diff) | |
| download | qemu-ipxe-b6eecb182e07a82bae2a5f8c28dadb1bea409090.tar.gz | |
[efi] Ensure NUL byte is at lowest address within stack cookiecookie
The NUL byte included within the stack cookie to act as a string
terminator should be placed at the lowest byte address within the
stack cookie, in order to avoid potentially including the stack cookie
value within an accidentally unterminated string.
Suggested-by: Pete Beck <pete.beck@ioactive.com>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
| -rw-r--r-- | src/interface/efi/efi_init.c | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/src/interface/efi/efi_init.c b/src/interface/efi/efi_init.c index 284c39b3..e1041a5e 100644 --- a/src/interface/efi/efi_init.c +++ b/src/interface/efi/efi_init.c @@ -21,6 +21,7 @@ FILE_LICENCE ( GPL2_OR_LATER ); #include <string.h> #include <errno.h> +#include <endian.h> #include <ipxe/init.h> #include <ipxe/rotate.h> #include <ipxe/efi/efi.h> @@ -128,6 +129,13 @@ efi_stack_cookie ( EFI_HANDLE handle ) { */ cookie <<= 8; + /* Ensure that the NUL byte is placed at the bottom of the + * stack cookie, to avoid potential disclosure via an + * unterminated string. + */ + if ( __BYTE_ORDER == __BIG_ENDIAN ) + cookie >>= 8; + return cookie; } |