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stub: clean up kernel command line when converting to ASCII

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Let's be a bit more careful when converting the UTF-16 cmdline to ASCII.
Let's convert all characters out of the printable ASCII range to spaces,
instead of blindly relying on C's downcasting behaviour.
This commit is contained in:
Lennart Poettering
2022-08-02 10:28:49 +02:00
parent 46d336722d
commit 03d5449f3a
1 changed files with 11 additions and 6 deletions
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src/boot/efi/stub.c
+11 -6
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@@ -238,14 +238,19 @@ EFI_STATUS efi_main(EFI_HANDLE image, EFI_SYSTEM_TABLE *sys_table) {
cmdline_len = szs[UNIFIED_SECTION_CMDLINE];
}
/* if we are not in secure boot mode, or none was provided, accept a custom command line and replace the built-in one */
if ((!secure_boot_enabled() || cmdline_len == 0) && loaded_image->LoadOptionsSize > 0 &&
*(char16_t *) loaded_image->LoadOptions > 0x1F) {
/* if we are not in secure boot mode, or none was provided, accept a custom command line and replace
* the built-in one. We also do a superficial check whether first chararacter of passed command line
* is printable character (for compat with some Dell systems which fill in garbage?). */
if ((!secure_boot_enabled() || cmdline_len == 0) &&
loaded_image->LoadOptionsSize > 0 &&
((char16_t *) loaded_image->LoadOptions)[0] > 0x1F) {
cmdline_len = (loaded_image->LoadOptionsSize / sizeof(char16_t)) * sizeof(char);
cmdline = cmdline_owned = xmalloc(cmdline_len);
cmdline = cmdline_owned = xnew(char, cmdline_len);
for (UINTN i = 0; i < cmdline_len; i++)
cmdline[i] = ((char16_t *) loaded_image->LoadOptions)[i];
for (UINTN i = 0; i < cmdline_len; i++) {
char16_t c = ((char16_t *) loaded_image->LoadOptions)[i];
cmdline[i] = c > 0x1F && c < 0x7F ? c : ' '; /* convert non-printable and non_ASCII characters to spaces. */
}
/* Let's measure the passed kernel command line into the TPM. Note that this possibly
* duplicates what we already did in the boot menu, if that was already used. However, since