linux-kernel - [GIT PULL] EFI fix

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Date:	Thu, 28 Apr 2016 19:48:43 +0200
From:	Ingo Molnar <mingo@...nel.org>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
Cc:	linux-kernel@...r.kernel.org, Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>,
	Matt Fleming <matt@...eblueprint.co.uk>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: [GIT PULL] EFI fix

Linus,

Please pull the latest efi-urgent-for-linus git tree from:

   git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git efi-urgent-for-linus

   # HEAD: ede85e90be26e5de2a72f76feec01cfc5281d4bd Merge tag 'efi-urgent' of git://git.kernel.org/pub/scm/linux/kernel/git/mfleming/efi into efi/urgent

This fixes a bug in the efivars code.

 Thanks,

	Ingo

------------------>
Laszlo Ersek (1):
      efi: Fix out-of-bounds read in variable_matches()


 drivers/firmware/efi/vars.c | 37 ++++++++++++++++++++++++++-----------
 1 file changed, 26 insertions(+), 11 deletions(-)

diff --git a/drivers/firmware/efi/vars.c b/drivers/firmware/efi/vars.c
index 0ac594c0a234..34b741940494 100644
--- a/drivers/firmware/efi/vars.c
+++ b/drivers/firmware/efi/vars.c
@@ -202,29 +202,44 @@ static const struct variable_validate variable_validate[] = {
 	{ NULL_GUID, "", NULL },
 };
 
+/*
+ * Check if @var_name matches the pattern given in @match_name.
+ *
+ * @var_name: an array of @len non-NUL characters.
+ * @match_name: a NUL-terminated pattern string, optionally ending in "*". A
+ *              final "*" character matches any trailing characters @var_name,
+ *              including the case when there are none left in @var_name.
+ * @match: on output, the number of non-wildcard characters in @match_name
+ *         that @var_name matches, regardless of the return value.
+ * @return: whether @var_name fully matches @match_name.
+ */
 static bool
 variable_matches(const char *var_name, size_t len, const char *match_name,
 		 int *match)
 {
 	for (*match = 0; ; (*match)++) {
 		char c = match_name[*match];
-		char u = var_name[*match];
 
-		/* Wildcard in the matching name means we've matched */
-		if (c == '*')
+		switch (c) {
+		case '*':
+			/* Wildcard in @match_name means we've matched. */
 			return true;
 
-		/* Case sensitive match */
-		if (!c && *match == len)
-			return true;
+		case '\0':
+			/* @match_name has ended. Has @var_name too? */
+			return (*match == len);
 
-		if (c != u)
+		default:
+			/*
+			 * We've reached a non-wildcard char in @match_name.
+			 * Continue only if there's an identical character in
+			 * @var_name.
+			 */
+			if (*match < len && c == var_name[*match])
+				continue;
 			return false;
-
-		if (!c)
-			return true;
+		}
 	}
-	return true;
 }
 
 bool