linux-kernel - [PATCH v3 01/11] stackleak: don't modify ctl

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Message-Id: <20240423-sysctl-const-handler-v3-1-e0beccb836e2@weissschuh.net>
Date: Tue, 23 Apr 2024 09:54:36 +0200
From: Thomas Weißschuh <linux@...ssschuh.net>
To: Luis Chamberlain <mcgrof@...nel.org>, 
 Joel Granados <j.granados@...sung.com>, Kees Cook <keescook@...omium.org>
Cc: Eric Dumazet <edumazet@...gle.com>, Dave Chinner <david@...morbit.com>, 
 linux-fsdevel@...r.kernel.org, netdev@...r.kernel.org, 
 linux-arm-kernel@...ts.infradead.org, linux-s390@...r.kernel.org, 
 linux-kernel@...r.kernel.org, linux-riscv@...ts.infradead.org, 
 linux-mm@...ck.org, linux-security-module@...r.kernel.org, 
 bpf@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org, 
 linux-xfs@...r.kernel.org, linux-trace-kernel@...r.kernel.org, 
 linux-perf-users@...r.kernel.org, netfilter-devel@...r.kernel.org, 
 coreteam@...filter.org, kexec@...ts.infradead.org, 
 linux-hardening@...r.kernel.org, bridge@...ts.linux.dev, 
 lvs-devel@...r.kernel.org, linux-rdma@...r.kernel.org, 
 rds-devel@....oracle.com, linux-sctp@...r.kernel.org, 
 linux-nfs@...r.kernel.org, apparmor@...ts.ubuntu.com, 
 Thomas Weißschuh <linux@...ssschuh.net>
Subject: [PATCH v3 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 d099f3affcf1..558b9d6d28d3 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