From: Thomas Weißschuh Date: Fri, 3 May 2024 13:44:09 +0000 (+0200) Subject: stackleak: Use a copy of the ctl_table argument X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=0e148d3cca0dc1a7c6063939f6cb9ba4866c39a7;p=linux.git 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: Luis Chamberlain Signed-off-by: Thomas Weißschuh Reviewed-by: Tycho Andersen Link: https://lore.kernel.org/r/20240503-sysctl-const-stackleak-v1-1-603fecb19170@weissschuh.net Signed-off-by: Kees Cook --- diff --git a/kernel/stackleak.c b/kernel/stackleak.c index 34c9d81eea940..59cdfaf5118e8 100644 --- a/kernel/stackleak.c +++ b/kernel/stackleak.c @@ -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;