Commit 7a88a622 authored Jun 15, 2020 by Philipp Fent Committed by Ard Biesheuvel Jun 15, 2020

efi/libstub: Fix path separator regression

Commit 9302c1bb ("efi/libstub: Rewrite file I/O routine") introduced a
regression that made a couple of (badly configured) systems fail to
boot [1]: Until 5.6, we silently accepted Unix-style file separators in
EFI paths, which might violate the EFI standard, but are an easy to make
mistake. This fix restores the pre-5.7 behaviour.

[1] https://bbs.archlinux.org/viewtopic.php?id=256273



Fixes: 9302c1bb ("efi/libstub: Rewrite file I/O routine")
Signed-off-by: Philipp Fent <fent@in.tum.de>
Link: https://lore.kernel.org/r/20200615115109.7823-1-fent@in.tum.de


[ardb: rewrite as chained if/else statements]
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>

parent 24552d10

drivers/firmware/efi/libstub/file.c

+12 −4

Original line number	Diff line number	Diff line
		@@ -102,12 +102,20 @@ static int find_file_option(const efi_char16_t *cmdline, int cmdline_len,
		if (!found)
		return 0;

		/* Skip any leading slashes */
		while (cmdline[i] == L'/' \|\| cmdline[i] == L'\\')
		i++;

		while (--result_len > 0 && i < cmdline_len) {
		if (cmdline[i] == L'\0' \|\|
		cmdline[i] == L'\n' \|\|
		cmdline[i] == L' ')
		efi_char16_t c = cmdline[i++];

		if (c == L'\0' \|\| c == L'\n' \|\| c == L' ')
		break;
		*result++ = cmdline[i++];
		else if (c == L'/')
		/* Replace UNIX dir separators with EFI standard ones */
		*result++ = L'\\';
		else
		*result++ = c;
		}
		*result = L'\0';
		return i;

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