Message-Id: <20240315-sysctl-const-handler-v1-1-1322ac7cb03d@weissschuh.net>
Date: Fri, 15 Mar 2024 21:47:59 +0100
From: Thomas Weißschuh <linux@...ssschuh.net>
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Cc: linux-hardening@...r.kernel.org, linux-kernel@...r.kernel.org, 
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 Thomas Weißschuh <linux@...ssschuh.net>
Subject: [PATCH 01/11] stackleak: don't modify ctl_table argument

In a future commit the proc_handlers will change to
"const struct ctl_table".
As a preparation for that adapt the logic to work with a temporary
variable, similar to how it is done in other parts of the kernel.

Fixes: 964c9dff0091 ("stackleak: Allow runtime disabling of kernel stack erasing")
Acked-by: Kees Cook <keescook@...omium.org>
Signed-off-by: Thomas Weißschuh <linux@...ssschuh.net>
---
 kernel/stackleak.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/kernel/stackleak.c b/kernel/stackleak.c
index 34c9d81eea94..b292e5ca0b7d 100644
--- a/kernel/stackleak.c
+++ b/kernel/stackleak.c
@@ -27,10 +27,11 @@ static int stack_erasing_sysctl(struct ctl_table *table, int write,
 	int ret = 0;
 	int state = !static_branch_unlikely(&stack_erasing_bypass);
 	int prev_state = state;
+	struct ctl_table tmp = *table;
 
-	table->data = &state;
-	table->maxlen = sizeof(int);
-	ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
+	tmp.data = &state;
+	tmp.maxlen = sizeof(int);
+	ret = proc_dointvec_minmax(&tmp, write, buffer, lenp, ppos);
 	state = !!state;
 	if (ret || !write || state == prev_state)
 		return ret;

-- 
2.44.0

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