[tip:efi/core] efi/libstub: Fix harmless command line parsing bug

[tip-bot for Ard Biesheuvel <tipbot@zytor.com>]

Commit-ID:  4c3f14bb87b683a2e5bbc6d6660b41893ecacfd0
Gitweb:     http://git.kernel.org/tip/4c3f14bb87b683a2e5bbc6d6660b41893ecacfd0
Author:     Ard Biesheuvel <ard.biesheuvel@linaro.org>
AuthorDate: Tue, 4 Apr 2017 17:02:45 +0100
Committer:  Ingo Molnar <mingo@kernel.org>
CommitDate: Wed, 5 Apr 2017 12:27:27 +0200

efi/libstub: Fix harmless command line parsing bug

When we parse the 'efi=' command line parameter in the stub, we
fail to take spaces into account. Currently, the only way this
could result in unexpected behavior is when the string 'nochunk'
appears as a separate command line argument after 'efi=xxx,yyy,zzz ',
so this is harmless in practice. But let's fix it nonetheless.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matt Fleming <matt@codeblueprint.co.uk>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-efi@vger.kernel.org
Link: http://lkml.kernel.org/r/20170404160245.27812-12-ard.biesheuvel@linaro.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
 drivers/firmware/efi/libstub/efi-stub-helper.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/firmware/efi/libstub/efi-stub-helper.c b/drivers/firmware/efi/libstub/efi-stub-helper.c
index 919822b..3290fae 100644
--- a/drivers/firmware/efi/libstub/efi-stub-helper.c
+++ b/drivers/firmware/efi/libstub/efi-stub-helper.c
@@ -436,14 +436,14 @@ efi_status_t efi_parse_options(char *cmdline)
 	 * Remember, because efi= is also used by the kernel we need to
 	 * skip over arguments we don't understand.
 	 */
-	while (*str) {
+	while (*str && *str != ' ') {
 		if (!strncmp(str, "nochunk", 7)) {
 			str += strlen("nochunk");
 			__chunk_size = -1UL;
 		}
 
 		/* Group words together, delimited by "," */
-		while (*str && *str != ',')
+		while (*str && *str != ' ' && *str != ',')
 			str++;
 
 		if (*str == ',')