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hostapd: fix SAE confirm missing state validation Published: April 10, 2019 Identifiers: - CVE-2019-9496 (SAE confirm missing state validation in hostapd/AP) Latest version available from: https://w1.fi/security/2019-3/ Vulnerability When hostapd is used to operate an access point with SAE (Simultaneous Authentication of Equals; also known as WPA3-Personal), an invalid authentication sequence could result in the hostapd process terminating due to a NULL pointer dereference when processing SAE confirm message. This was caused by missing state validation steps when processing the SAE confirm message in hostapd/AP mode. Similar cases against the wpa_supplicant SAE station implementation had already been tested by the hwsim test cases, but those sequences did not trigger this specific code path in AP mode which is why the issue was not discovered earlier. An attacker in radio range of an access point using hostapd in SAE configuration could use this issue to perform a denial of service attack by forcing the hostapd process to terminate. Vulnerable versions/configurations All hostapd versions with SAE support (CONFIG_SAE=y in the build configuration and SAE being enabled in the runtime configuration). Possible mitigation steps - Merge the following commit to hostapd and rebuild: SAE: Fix confirm message validation in error cases These patches are available from https://w1.fi/security/2019-3/ - Update to hostapd v2.8 or newer, once available Signed-off-by: Stefan Lippers-Hollmann <s.l-h@gmx.de> [bump PKG_RELEASE] Signed-off-by: Jo-Philipp Wich <jo@mein.io>
53 lines
1.7 KiB
Diff
53 lines
1.7 KiB
Diff
From ac8fa9ef198640086cf2ce7c94673be2b6a018a0 Mon Sep 17 00:00:00 2001
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From: Jouni Malinen <jouni@codeaurora.org>
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Date: Tue, 5 Mar 2019 23:43:25 +0200
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Subject: [PATCH 10/14] SAE: Fix confirm message validation in error cases
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Explicitly verify that own and peer commit scalar/element are available
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when trying to check SAE confirm message. It could have been possible to
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hit a NULL pointer dereference if the peer element could not have been
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parsed. (CVE-2019-9496)
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Signed-off-by: Jouni Malinen <jouni@codeaurora.org>
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---
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src/common/sae.c | 14 +++++++++++---
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1 file changed, 11 insertions(+), 3 deletions(-)
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--- a/src/common/sae.c
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+++ b/src/common/sae.c
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@@ -1464,23 +1464,31 @@ int sae_check_confirm(struct sae_data *s
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wpa_printf(MSG_DEBUG, "SAE: peer-send-confirm %u", WPA_GET_LE16(data));
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- if (sae->tmp == NULL) {
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+ if (!sae->tmp || !sae->peer_commit_scalar ||
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+ !sae->tmp->own_commit_scalar) {
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wpa_printf(MSG_DEBUG, "SAE: Temporary data not yet available");
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return -1;
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}
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- if (sae->tmp->ec)
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+ if (sae->tmp->ec) {
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+ if (!sae->tmp->peer_commit_element_ecc ||
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+ !sae->tmp->own_commit_element_ecc)
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+ return -1;
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sae_cn_confirm_ecc(sae, data, sae->peer_commit_scalar,
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sae->tmp->peer_commit_element_ecc,
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sae->tmp->own_commit_scalar,
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sae->tmp->own_commit_element_ecc,
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verifier);
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- else
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+ } else {
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+ if (!sae->tmp->peer_commit_element_ffc ||
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+ !sae->tmp->own_commit_element_ffc)
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+ return -1;
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sae_cn_confirm_ffc(sae, data, sae->peer_commit_scalar,
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sae->tmp->peer_commit_element_ffc,
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sae->tmp->own_commit_scalar,
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sae->tmp->own_commit_element_ffc,
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verifier);
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+ }
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if (os_memcmp_const(verifier, data + 2, SHA256_MAC_LEN) != 0) {
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wpa_printf(MSG_DEBUG, "SAE: Confirm mismatch");
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