From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: stable@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
patches@lists.linux.dev, Liuye <liu.yeC@h3c.com>,
Douglas Anderson <dianders@chromium.org>,
Daniel Thompson <daniel.thompson@linaro.org>
Subject: [PATCH 5.15 19/23] serial: kgdboc: Fix NMI-safety problems from keyboard reset code
Date: Thu, 23 May 2024 15:13:15 +0200 [thread overview]
Message-ID: <20240523130328.676074925@linuxfoundation.org> (raw)
In-Reply-To: <20240523130327.956341021@linuxfoundation.org>
5.15-stable review patch. If anyone has any objections, please let me know.
------------------
From: Daniel Thompson <daniel.thompson@linaro.org>
commit b2aba15ad6f908d1a620fd97f6af5620c3639742 upstream.
Currently, when kdb is compiled with keyboard support, then we will use
schedule_work() to provoke reset of the keyboard status. Unfortunately
schedule_work() gets called from the kgdboc post-debug-exception
handler. That risks deadlock since schedule_work() is not NMI-safe and,
even on platforms where the NMI is not directly used for debugging, the
debug trap can have NMI-like behaviour depending on where breakpoints
are placed.
Fix this by using the irq work system, which is NMI-safe, to defer the
call to schedule_work() to a point when it is safe to call.
Reported-by: Liuye <liu.yeC@h3c.com>
Closes: https://lore.kernel.org/all/20240228025602.3087748-1-liu.yeC@h3c.com/
Cc: stable@vger.kernel.org
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lore.kernel.org/r/20240424-kgdboc_fix_schedule_work-v2-1-50f5a490aec5@linaro.org
Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/tty/serial/kgdboc.c | 30 +++++++++++++++++++++++++++++-
1 file changed, 29 insertions(+), 1 deletion(-)
--- a/drivers/tty/serial/kgdboc.c
+++ b/drivers/tty/serial/kgdboc.c
@@ -19,6 +19,7 @@
#include <linux/console.h>
#include <linux/vt_kern.h>
#include <linux/input.h>
+#include <linux/irq_work.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/serial_core.h>
@@ -48,6 +49,25 @@ static struct kgdb_io kgdboc_earlycon_i
static int (*earlycon_orig_exit)(struct console *con);
#endif /* IS_BUILTIN(CONFIG_KGDB_SERIAL_CONSOLE) */
+/*
+ * When we leave the debug trap handler we need to reset the keyboard status
+ * (since the original keyboard state gets partially clobbered by kdb use of
+ * the keyboard).
+ *
+ * The path to deliver the reset is somewhat circuitous.
+ *
+ * To deliver the reset we register an input handler, reset the keyboard and
+ * then deregister the input handler. However, to get this done right, we do
+ * have to carefully manage the calling context because we can only register
+ * input handlers from task context.
+ *
+ * In particular we need to trigger the action from the debug trap handler with
+ * all its NMI and/or NMI-like oddities. To solve this the kgdboc trap exit code
+ * (the "post_exception" callback) uses irq_work_queue(), which is NMI-safe, to
+ * schedule a callback from a hardirq context. From there we have to defer the
+ * work again, this time using schedule_work(), to get a callback using the
+ * system workqueue, which runs in task context.
+ */
#ifdef CONFIG_KDB_KEYBOARD
static int kgdboc_reset_connect(struct input_handler *handler,
struct input_dev *dev,
@@ -99,10 +119,17 @@ static void kgdboc_restore_input_helper(
static DECLARE_WORK(kgdboc_restore_input_work, kgdboc_restore_input_helper);
+static void kgdboc_queue_restore_input_helper(struct irq_work *unused)
+{
+ schedule_work(&kgdboc_restore_input_work);
+}
+
+static DEFINE_IRQ_WORK(kgdboc_restore_input_irq_work, kgdboc_queue_restore_input_helper);
+
static void kgdboc_restore_input(void)
{
if (likely(system_state == SYSTEM_RUNNING))
- schedule_work(&kgdboc_restore_input_work);
+ irq_work_queue(&kgdboc_restore_input_irq_work);
}
static int kgdboc_register_kbd(char **cptr)
@@ -133,6 +160,7 @@ static void kgdboc_unregister_kbd(void)
i--;
}
}
+ irq_work_sync(&kgdboc_restore_input_irq_work);
flush_work(&kgdboc_restore_input_work);
}
#else /* ! CONFIG_KDB_KEYBOARD */
next prev parent reply other threads:[~2024-05-23 13:19 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-05-23 13:12 [PATCH 5.15 00/23] 5.15.160-rc1 review Greg Kroah-Hartman
2024-05-23 13:12 ` [PATCH 5.15 01/23] drm/amd/display: Fix division by zero in setup_dsc_config Greg Kroah-Hartman
2024-05-23 13:12 ` [PATCH 5.15 02/23] pinctrl: core: handle radix_tree_insert() errors in pinctrl_register_one_pin() Greg Kroah-Hartman
2024-05-23 13:12 ` [PATCH 5.15 03/23] nfsd: dont allow nfsd threads to be signalled Greg Kroah-Hartman
2024-05-23 13:13 ` [PATCH 5.15 04/23] KEYS: trusted: Fix memory leak in tpm2_key_encode() Greg Kroah-Hartman
2024-05-23 13:13 ` [PATCH 5.15 05/23] Revert "selftests: mm: fix map_hugetlb failure on 64K page size systems" Greg Kroah-Hartman
2024-05-23 13:13 ` [PATCH 5.15 06/23] net: bcmgenet: synchronize EXT_RGMII_OOB_CTRL access Greg Kroah-Hartman
2024-05-23 13:13 ` [PATCH 5.15 07/23] net: bcmgenet: synchronize UMAC_CMD access Greg Kroah-Hartman
2024-05-23 13:13 ` [PATCH 5.15 08/23] tls: rx: simplify async wait Greg Kroah-Hartman
2024-05-23 13:13 ` [PATCH 5.15 09/23] tls: extract context alloc/initialization out of tls_set_sw_offload Greg Kroah-Hartman
2024-05-23 13:13 ` [PATCH 5.15 10/23] net: tls: factor out tls_*crypt_async_wait() Greg Kroah-Hartman
2024-05-23 13:13 ` [PATCH 5.15 11/23] tls: fix race between async notify and socket close Greg Kroah-Hartman
2024-05-23 13:13 ` [PATCH 5.15 12/23] net: tls: handle backlogging of crypto requests Greg Kroah-Hartman
2024-05-23 13:13 ` [PATCH 5.15 13/23] netlink: annotate lockless accesses to nlk->max_recvmsg_len Greg Kroah-Hartman
2024-05-23 13:13 ` [PATCH 5.15 14/23] netlink: annotate data-races around sk->sk_err Greg Kroah-Hartman
2024-05-23 13:13 ` [PATCH 5.15 15/23] KVM: x86: Clear "has_error_code", not "error_code", for RM exception injection Greg Kroah-Hartman
2024-05-23 13:13 ` [PATCH 5.15 16/23] drm/amdgpu: Fix possible NULL dereference in amdgpu_ras_query_error_status_helper() Greg Kroah-Hartman
2024-05-23 13:13 ` [PATCH 5.15 17/23] binder: fix max_thread type inconsistency Greg Kroah-Hartman
2024-05-23 13:13 ` [PATCH 5.15 18/23] usb: typec: ucsi: displayport: Fix potential deadlock Greg Kroah-Hartman
2024-05-23 13:13 ` Greg Kroah-Hartman [this message]
2024-05-23 13:13 ` [PATCH 5.15 20/23] remoteproc: mediatek: Make sure IPI buffer fits in L2TCM Greg Kroah-Hartman
2024-05-23 13:13 ` [PATCH 5.15 21/23] KEYS: trusted: Do not use WARN when encode fails Greg Kroah-Hartman
2024-05-23 13:13 ` [PATCH 5.15 22/23] admin-guide/hw-vuln/core-scheduling: fix return type of PR_SCHED_CORE_GET Greg Kroah-Hartman
2024-05-23 13:13 ` [PATCH 5.15 23/23] docs: kernel_include.py: Cope with docutils 0.21 Greg Kroah-Hartman
2024-05-23 17:02 ` [PATCH 5.15 00/23] 5.15.160-rc1 review SeongJae Park
2024-05-23 18:20 ` Mark Brown
2024-05-23 18:50 ` Florian Fainelli
2024-05-24 6:54 ` Harshit Mogalapalli
2024-05-24 8:16 ` Anders Roxell
2024-05-24 14:36 ` Shuah Khan
2024-05-24 20:44 ` Ron Economos
2024-05-24 23:13 ` Jon Hunter
2024-05-25 14:20 ` Greg Kroah-Hartman
2024-05-28 9:04 ` Jon Hunter
2024-05-28 13:14 ` Chuck Lever III
2024-05-28 14:18 ` Jon Hunter
2024-05-28 20:38 ` Chris Packham
2024-05-28 20:55 ` Chuck Lever III
2024-05-28 22:01 ` NeilBrown
2024-05-28 23:33 ` Chuck Lever III
2024-05-28 23:44 ` NeilBrown
2024-05-29 0:13 ` Chuck Lever III
2024-05-28 23:42 ` NeilBrown
2024-05-29 8:59 ` Jon Hunter
2024-05-29 20:59 ` NeilBrown
2024-05-30 12:11 ` Jon Hunter
2024-06-06 14:32 ` Chuck Lever
2024-06-03 13:44 ` Chuck Lever III
2024-05-25 0:58 ` Kelsey Steele
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