From c31b14d86dfe7174361e8c6e5df6c2c3a4d5918c Mon Sep 17 00:00:00 2001 From: "Jason A. Donenfeld" Date: Tue, 2 Aug 2022 14:56:12 +0200 Subject: wireguard: allowedips: don't corrupt stack when detecting overflow In case push_rcu() and related functions are buggy, there's a WARN_ON(len >= 128), which the selftest tries to hit by being tricky. In case it is hit, we shouldn't corrupt the kernel's stack, though; otherwise it may be hard to even receive the report that it's buggy. So conditionalize the stack write based on that WARN_ON()'s return value. Note that this never *actually* happens anyway. The WARN_ON() in the first place is bounded by IS_ENABLED(DEBUG), and isn't expected to ever actually hit. This is just a debugging sanity check. Additionally, hoist the constant 128 into a named enum, MAX_ALLOWEDIPS_BITS, so that it's clear why this value is chosen. Suggested-by: Linus Torvalds Link: https://lore.kernel.org/all/CAHk-=wjJZGA6w_DxA+k7Ejbqsq+uGK==koPai3sqdsfJqemvag@mail.gmail.com/ Fixes: e7096c131e51 ("net: WireGuard secure network tunnel") Signed-off-by: Jason A. Donenfeld Signed-off-by: Jakub Kicinski --- drivers/net/wireguard/selftest/allowedips.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'drivers/net/wireguard/selftest/allowedips.c') diff --git a/drivers/net/wireguard/selftest/allowedips.c b/drivers/net/wireguard/selftest/allowedips.c index e173204ae7d7..41db10f9be49 100644 --- a/drivers/net/wireguard/selftest/allowedips.c +++ b/drivers/net/wireguard/selftest/allowedips.c @@ -593,10 +593,10 @@ bool __init wg_allowedips_selftest(void) wg_allowedips_remove_by_peer(&t, a, &mutex); test_negative(4, a, 192, 168, 0, 1); - /* These will hit the WARN_ON(len >= 128) in free_node if something - * goes wrong. + /* These will hit the WARN_ON(len >= MAX_ALLOWEDIPS_BITS) in free_node + * if something goes wrong. */ - for (i = 0; i < 128; ++i) { + for (i = 0; i < MAX_ALLOWEDIPS_BITS; ++i) { part = cpu_to_be64(~(1LLU << (i % 64))); memset(&ip, 0xff, 16); memcpy((u8 *)&ip + (i < 64) * 8, &part, 8); -- cgit v1.2.3-59-g8ed1b