Commit 0e148d3c authored by Thomas Weißschuh's avatar Thomas Weißschuh Committed by Kees Cook
Browse files

stackleak: Use a copy of the ctl_table argument 



Sysctl handlers are not supposed to modify the ctl_table passed to them.
Adapt the logic to work with a temporary variable, similar to how it is
done in other parts of the kernel.

This is also a prerequisite to enforce the immutability of the argument
through the callbacks.

Reviewed-by: default avatarLuis Chamberlain <mcgrof@kernel.org>
Signed-off-by: default avatarThomas Weißschuh <linux@weissschuh.net>
Reviewed-by: default avatarTycho Andersen <tycho@tycho.pizza>
Link: https://lore.kernel.org/r/20240503-sysctl-const-stackleak-v1-1-603fecb19170@weissschuh.net


Signed-off-by: default avatarKees Cook <keescook@chromium.org>
parent 7d78a777

kernel/stackleak.c

+3 −3
Original line number Diff line number Diff line
@@ -27,10 +27,10 @@ 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 table_copy = *table;



	table->data = &state;

	table->maxlen = sizeof(int);

	ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);

	table_copy.data = &state;

	ret = proc_dointvec_minmax(&table_copy, write, buffer, lenp, ppos);

	state = !!state;

	if (ret || !write || state == prev_state)

		return ret;