linux-kernel - [RFC 04/31] kernel/sys: Don't reference UTS

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Message-ID: <203eaa28b60bef8f4396beed554358e3c2483a07.1725334260.git.jpoimboe@kernel.org>
Date: Mon,  2 Sep 2024 20:59:47 -0700
From: Josh Poimboeuf <jpoimboe@...nel.org>
To: live-patching@...r.kernel.org
Cc: linux-kernel@...r.kernel.org,
	x86@...nel.org,
	Miroslav Benes <mbenes@...e.cz>,
	Petr Mladek <pmladek@...e.com>,
	Joe Lawrence <joe.lawrence@...hat.com>,
	Jiri Kosina <jikos@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Marcos Paulo de Souza <mpdesouza@...e.com>,
	Song Liu <song@...nel.org>
Subject: [RFC 04/31] kernel/sys: Don't reference UTS_RELEASE directly

Objtool will be getting a new feature to calculate build-time function
checksums, so each function can be uniquely identified.  A function's
checksum is calculated based on its instructions, jump/call targets,
alternatives, string literals, and more.

When there are any changes to the git working tree, UTS_RELEASE is
suffixed with "+".  That can result in an undesired changed checksum for
the functions which inline override_release() due to its direct
reference of the UTS_RELEASE string literal.

Convert the override_release() 'rest' variable to a static local so it
won't affect function checksums.

Signed-off-by: Josh Poimboeuf <jpoimboe@...nel.org>
---
 kernel/sys.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/sys.c b/kernel/sys.c
index 3a2df1bd9f64..526464ea194b 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -1291,7 +1291,7 @@ static int override_release(char __user *release, size_t len)
 	int ret = 0;

 	if (current->personality & UNAME26) {
-		const char *rest = UTS_RELEASE;
+		static const char *rest = UTS_RELEASE;
 		char buf[65] = { 0 };
 		int ndots = 0;
 		unsigned v;
-- 
2.45.2