linux-kernel - [PATCH] thunderbolt: Clear hops before overwriting

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-Id: <1409067741-3378-1-git-send-email-andreas.noever@gmail.com>
Date:	Tue, 26 Aug 2014 17:42:21 +0200
From:	Andreas Noever <andreas.noever@...il.com>
To:	linux-kernel@...r.kernel.org, Greg KH <greg@...ah.com>
Cc:	Andreas Noever <andreas.noever@...il.com>
Subject: [PATCH] thunderbolt: Clear hops before overwriting

Zero hops in tb_path_activate before writing a new path.

This fixes the following scenario:
 - Boot with a coldplugged device
 - Unplug device
 - Plug device back in
 - PCI hotplug fails

The hotplug operation fails because our new path matches the (now
defunct) path which was setup by the firmware for the coldplugged
device. By writing zeros before writing our path configuration we can
force thunderbolt to retrain the path.

Signed-off-by: Andreas Noever <andreas.noever@...il.com>
---
 drivers/thunderbolt/path.c | 21 ++++++++++++++++++++-
 1 file changed, 20 insertions(+), 1 deletion(-)

diff --git a/drivers/thunderbolt/path.c b/drivers/thunderbolt/path.c
index 8fcf8a7..9562cd0 100644
--- a/drivers/thunderbolt/path.c
+++ b/drivers/thunderbolt/path.c
@@ -150,7 +150,26 @@ int tb_path_activate(struct tb_path *path)
 
 	/* Activate hops. */
 	for (i = path->path_length - 1; i >= 0; i--) {
-		struct tb_regs_hop hop;
+		struct tb_regs_hop hop = { 0 };
+
+		/*
+		 * We do (currently) not tear down paths setup by the firmeware.
+		 * If a firmware device is unplugged and plugged in again then
+		 * it can happen that we reuse some of the hops from the (now
+		 * defunct) firmeware path. This causes the hotplug operation to
+		 * fail (the pci device does not show up). Clearing the hop
+		 * before overwriting it fixes the problem.
+		 *
+		 * Should be removed once we discover and tear down firmeware
+		 * paths.
+		 */
+		res = tb_port_write(path->hops[i].in_port, &hop, TB_CFG_HOPS,
+				    2 * path->hops[i].in_hop_index, 2);
+		if (res) {
+			__tb_path_deactivate_hops(path, i);
+			__tb_path_deallocate_nfc(path, 0);
+			goto err;
+		}
 
 		/* dword 0 */
 		hop.next_hop = path->hops[i].next_hop_index;
-- 
2.1.0

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/