[PATCH v3 01/11] stackleak: don't modify ctl_table argument

Thomas Weißschuh <[email protected]>
Newsgroups org.kernel.vger.lvs-devel,dev.linux.lists.bridge,org.infradead.lists.kexec,org.infradead.lists.linux-arm-kernel,org.infradead.lists.linux-riscv,org.kernel.vger.bpf,org.kernel.vger.linux-fsdevel,org.kernel.vger.linux-hardening,org.kernel.vger.linux-kernel,org.kernel.vger.linux-nfs,org.kernel.vger.linux-perf-users,org.kernel.vger.linux-rdma,org.kernel.vger.linux-s390,org.kernel.vger.linux-sctp,org.kernel.vger.linux-security-module,org.kernel.vger.linux-trace-kernel,org.kernel.vger.linux-xfs,org.kernel.vger.netdev,org.kernel.vger.netfilter-devel,org.kvack.linux-mm,org.ozlabs.lists.linuxppc-dev
Message-ID <[email protected]>
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 <[email protected]>
Signed-off-by: Thomas Weißschuh <[email protected]>
---
 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
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