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Commit f36dd10d authored by Kees Cook's avatar Kees Cook Committed by Greg Kroah-Hartman
Browse files

gcc-plugins/stackleak: Exactly match strings instead of prefixes 



[ Upstream commit 27e9faf415dbf94af19b9c827842435edbc1fbbc ]

Since STRING_CST may not be NUL terminated, strncmp() was used for check
for equality. However, this may lead to mismatches for longer section
names where the start matches the tested-for string. Test for exact
equality by checking for the presences of NUL termination.

Cc: Alexander Popov <alex.popov@linux.com>
Signed-off-by: default avatarKees Cook <keescook@chromium.org>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent ddcdda88

scripts/gcc-plugins/stackleak_plugin.c

+21 −4
Original line number Diff line number Diff line
@@ -262,6 +262,23 @@ static unsigned int stackleak_cleanup_execute(void) 
	return 0;

}



/*

 * STRING_CST may or may not be NUL terminated:

 * https://gcc.gnu.org/onlinedocs/gccint/Constant-expressions.html

 */

static inline bool string_equal(tree node, const char *string, int length)

{

	if (TREE_STRING_LENGTH(node) < length)

		return false;

	if (TREE_STRING_LENGTH(node) > length + 1)

		return false;

	if (TREE_STRING_LENGTH(node) == length + 1 &&

	    TREE_STRING_POINTER(node)[length] != '\0')

		return false;

	return !memcmp(TREE_STRING_POINTER(node), string, length);

}

#define STRING_EQUAL(node, str)	string_equal(node, str, strlen(str))



static bool stackleak_gate(void)

{

	tree section;
@@ -271,13 +288,13 @@ static bool stackleak_gate(void) 
	if (section && TREE_VALUE(section)) {

		section = TREE_VALUE(TREE_VALUE(section));



		if (!strncmp(TREE_STRING_POINTER(section), ".init.text", 10))

		if (STRING_EQUAL(section, ".init.text"))

			return false;

		if (!strncmp(TREE_STRING_POINTER(section), ".devinit.text", 13))

		if (STRING_EQUAL(section, ".devinit.text"))

			return false;

		if (!strncmp(TREE_STRING_POINTER(section), ".cpuinit.text", 13))

		if (STRING_EQUAL(section, ".cpuinit.text"))

			return false;

		if (!strncmp(TREE_STRING_POINTER(section), ".meminit.text", 13))

		if (STRING_EQUAL(section, ".meminit.text"))

			return false;

	}