From 4352b8aee98005853aa63f57d6377282de17a33f Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Sun, 23 Aug 2026 13:28:57 -0700 Subject: Merge tag 'i3c/for-7.3' of git://git.kernel.org/pub/scm/linux/kernel/git/i3c/linux Pull I3C updates from Alexandre Belloni: "A new driver this cycle, for the AMD AXI I3C controller. There are also new features such as IBI wakeup support, SETAASA device discovery and ACPI support for the the DAA methods, meaning we can now communicate with the SPD devices on DDR5 modules. New driver: - AMD AXI I3C master controller Subsystem: - I3C Common Command Code (CCC) handling improvements, especially around GET CCCs - SETAASA device discovery support - ACPI support for all existing DAA methods like SETDASA, SETNEWDA as well as I2C devices on I3C bus - IBI-based wakeup support Drivers: - dw: SETAASA support - mipi-i3c-hci: advertise IBI wakeup capability, AMD_PT I3C controller support, PIO queue management support for HCI v1.2 - renesas: improve suspend to RAM support, add runtime PM support" * tag 'i3c/for-7.3' of git://git.kernel.org/pub/scm/linux/kernel/git/i3c/linux: (70 commits) i3c: dw: reduce do_daa time if there's no client i3c: mipi-i3c-hci: Add support for AMD_PT I3C controller i3c: mipi-i3c-hci: Add PIO queue management support for HCI v1.2 i3c: mipi-i3c-hci: Fix missing STAT_IBI_STATUS_THLD in PIO mode i3c: dw: rename "pclk" to "apb" to match dt-binding i3c: dw: make struct dw_i3c_cmd smaller i3c: dw: use COMMAND_PORT_TRANSFER_ARG instead of hardcoding i3c: renesas: Don't register devices when ENTDAA times out i3c: master: dw-i3c-master: fix OD timing for first broadcast i3c: mipi-i3c-hci: Advertise IBI wakeup capability i3c: mipi-i3c-hci: Factor out i3c_hci_sysdev() i3c: mipi-i3c-hci-pci: Propagate I3C wakeup requirements to PCI i3c: master: Reject IBI requests from non-IBI-capable devices i3c: master: Add helper to query bus wakeup requirements i3c: master: Report wakeup events for IBIs i3c: master: Support IBI-based wakeup capability i3c: master: Fix potential UAF in i3c_device_match() i3c: master: Fix potential UAF in i3c_device_uevent() i3c: Make dev->desc locking assumptions explicit i3c: master: Fix use-after-free of master->this ... --- samples/livepatch/livepatch-shadow-mod.c | 212 +++++++++++++++++++++++++++++++ 1 file changed, 212 insertions(+) create mode 100644 samples/livepatch/livepatch-shadow-mod.c (limited to 'samples/livepatch/livepatch-shadow-mod.c') diff --git a/samples/livepatch/livepatch-shadow-mod.c b/samples/livepatch/livepatch-shadow-mod.c new file mode 100644 index 000000000..5d83ad5a8 --- /dev/null +++ b/samples/livepatch/livepatch-shadow-mod.c @@ -0,0 +1,212 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Copyright (C) 2017 Joe Lawrence + */ + +/* + * livepatch-shadow-mod.c - Shadow variables, buggy module demo + * + * Purpose + * ------- + * + * As a demonstration of livepatch shadow variable API, this module + * introduces memory leak behavior that livepatch modules + * livepatch-shadow-fix1.ko and livepatch-shadow-fix2.ko correct and + * enhance. + * + * WARNING - even though the livepatch-shadow-fix modules patch the + * memory leak, please load these modules at your own risk -- some + * amount of memory may leaked before the bug is patched. + * + * + * Usage + * ----- + * + * Step 1 - Load the buggy demonstration module: + * + * insmod samples/livepatch/livepatch-shadow-mod.ko + * + * Watch dmesg output for a few moments to see new dummy being allocated + * and a periodic cleanup check. (Note: a small amount of memory is + * being leaked.) + * + * + * Step 2 - Load livepatch fix1: + * + * insmod samples/livepatch/livepatch-shadow-fix1.ko + * + * Continue watching dmesg and note that now livepatch_fix1_dummy_free() + * and livepatch_fix1_dummy_alloc() are logging messages about leaked + * memory and eventually leaks prevented. + * + * + * Step 3 - Load livepatch fix2 (on top of fix1): + * + * insmod samples/livepatch/livepatch-shadow-fix2.ko + * + * This module extends functionality through shadow variables, as a new + * "check" counter is added to the dummy structure. Periodic dmesg + * messages will log these as dummies are cleaned up. + * + * + * Step 4 - Cleanup + * + * Unwind the demonstration by disabling the livepatch fix modules, then + * removing them and the demo module: + * + * echo 0 > /sys/kernel/livepatch/livepatch_shadow_fix2/enabled + * echo 0 > /sys/kernel/livepatch/livepatch_shadow_fix1/enabled + * rmmod livepatch-shadow-fix2 + * rmmod livepatch-shadow-fix1 + * rmmod livepatch-shadow-mod + */ + + +#include +#include +#include +#include +#include +#include + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Joe Lawrence "); +MODULE_DESCRIPTION("Buggy module for shadow variable demo"); + +/* Allocate new dummies every second */ +#define ALLOC_PERIOD 1 +/* Check for expired dummies after a few new ones have been allocated */ +#define CLEANUP_PERIOD (3 * ALLOC_PERIOD) +/* Dummies expire after a few cleanup instances */ +#define EXPIRE_PERIOD (4 * CLEANUP_PERIOD) + +/* + * Keep a list of all the dummies so we can clean up any residual ones + * on module exit + */ +static LIST_HEAD(dummy_list); +static DEFINE_MUTEX(dummy_list_mutex); + +struct dummy { + struct list_head list; + unsigned long jiffies_expire; +}; + +static __used noinline struct dummy *dummy_alloc(void) +{ + struct dummy *d; + int *leak; + + d = kzalloc(sizeof(*d), GFP_KERNEL); + if (!d) + return NULL; + + d->jiffies_expire = jiffies + secs_to_jiffies(EXPIRE_PERIOD); + + /* Oops, forgot to save leak! */ + leak = kzalloc(sizeof(*leak), GFP_KERNEL); + if (!leak) { + kfree(d); + return NULL; + } + + pr_info("%s: dummy @ %p, expires @ %lx\n", + __func__, d, d->jiffies_expire); + + return d; +} + +static __used noinline void dummy_free(struct dummy *d) +{ + pr_info("%s: dummy @ %p, expired = %lx\n", + __func__, d, d->jiffies_expire); + + kfree(d); +} + +static __used noinline bool dummy_check(struct dummy *d, + unsigned long jiffies) +{ + return time_after(jiffies, d->jiffies_expire); +} + +/* + * alloc_work_func: allocates new dummy structures, allocates additional + * memory, aptly named "leak", but doesn't keep + * permanent record of it. + */ + +static void alloc_work_func(struct work_struct *work); +static DECLARE_DELAYED_WORK(alloc_dwork, alloc_work_func); + +static void alloc_work_func(struct work_struct *work) +{ + struct dummy *d; + + d = dummy_alloc(); + if (!d) + return; + + mutex_lock(&dummy_list_mutex); + list_add(&d->list, &dummy_list); + mutex_unlock(&dummy_list_mutex); + + schedule_delayed_work(&alloc_dwork, secs_to_jiffies(ALLOC_PERIOD)); +} + +/* + * cleanup_work_func: frees dummy structures. Without knownledge of + * "leak", it leaks the additional memory that + * alloc_work_func created. + */ + +static void cleanup_work_func(struct work_struct *work); +static DECLARE_DELAYED_WORK(cleanup_dwork, cleanup_work_func); + +static void cleanup_work_func(struct work_struct *work) +{ + struct dummy *d, *tmp; + unsigned long j; + + j = jiffies; + pr_info("%s: jiffies = %lx\n", __func__, j); + + mutex_lock(&dummy_list_mutex); + list_for_each_entry_safe(d, tmp, &dummy_list, list) { + + /* Kick out and free any expired dummies */ + if (dummy_check(d, j)) { + list_del(&d->list); + dummy_free(d); + } + } + mutex_unlock(&dummy_list_mutex); + + schedule_delayed_work(&cleanup_dwork, secs_to_jiffies(CLEANUP_PERIOD)); +} + +static int livepatch_shadow_mod_init(void) +{ + schedule_delayed_work(&alloc_dwork, secs_to_jiffies(ALLOC_PERIOD)); + schedule_delayed_work(&cleanup_dwork, secs_to_jiffies(CLEANUP_PERIOD)); + + return 0; +} + +static void livepatch_shadow_mod_exit(void) +{ + struct dummy *d, *tmp; + + /* Wait for any dummies at work */ + cancel_delayed_work_sync(&alloc_dwork); + cancel_delayed_work_sync(&cleanup_dwork); + + /* Cleanup residual dummies */ + list_for_each_entry_safe(d, tmp, &dummy_list, list) { + list_del(&d->list); + dummy_free(d); + } +} + +module_init(livepatch_shadow_mod_init); +module_exit(livepatch_shadow_mod_exit); -- cgit v1.3.1