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| author | Linus Torvalds <torvalds@linux-foundation.org> | 2026-09-25 15:55:03 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2026-09-25 15:55:03 -0700 |
| commit | 75467f60a3d14f08f86f2b353298d2826382ff23 (patch) | |
| tree | acd8a7d5b5a675042449386efa5b42ec44d8bf81 /samples/livepatch/livepatch-shadow-fix2.c | |
| download | linux-stable-75467f60a3d14f08f86f2b353298d2826382ff23.tar.gz linux-stable-75467f60a3d14f08f86f2b353298d2826382ff23.zip | |
Merge tag 'ipe-pr-20260925' of git://git.kernel.org/pub/scm/linux/kernel/git/wufan/ipegrafted
Pull IPE fixes from Fan Wu:
"Two fixes for use-after-free issues found by recent LLM-assisted code
analysis.
- move successful policy load auditing under the new policy
directory's inode lock, preventing a concurrent policy deletion
from freeing the policy while it is still being audited
- protect the dm-verity root hash with RCU, preventing policy
evaluation from racing with root hash replacement during preresume"
* tag 'ipe-pr-20260925' of git://git.kernel.org/pub/scm/linux/kernel/git/wufan/ipe:
ipe: protect the dm-verity root hash with RCU
ipe: fix use-after-free when auditing a newly loaded policy
Diffstat (limited to 'samples/livepatch/livepatch-shadow-fix2.c')
| -rw-r--r-- | samples/livepatch/livepatch-shadow-fix2.c | 133 |
1 files changed, 133 insertions, 0 deletions
diff --git a/samples/livepatch/livepatch-shadow-fix2.c b/samples/livepatch/livepatch-shadow-fix2.c new file mode 100644 index 000000000..b99122cb2 --- /dev/null +++ b/samples/livepatch/livepatch-shadow-fix2.c @@ -0,0 +1,133 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Copyright (C) 2017 Joe Lawrence <joe.lawrence@redhat.com> + */ + +/* + * livepatch-shadow-fix2.c - Shadow variables, livepatch demo + * + * Purpose + * ------- + * + * Adds functionality to livepatch-shadow-mod's in-flight data + * structures through a shadow variable. The livepatch patches a + * routine that periodically inspects data structures, incrementing a + * per-data-structure counter, creating the counter if needed. + * + * + * Usage + * ----- + * + * This module is not intended to be standalone. See the "Usage" + * section of livepatch-shadow-mod.c. + */ + +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include <linux/module.h> +#include <linux/kernel.h> +#include <linux/livepatch.h> +#include <linux/slab.h> + +/* Shadow variable enums */ +#define SV_LEAK 1 +#define SV_COUNTER 2 + +struct dummy { + struct list_head list; + unsigned long jiffies_expire; +}; + +static bool livepatch_fix2_dummy_check(struct dummy *d, unsigned long jiffies) +{ + int *shadow_count; + + /* + * Patch: handle in-flight dummy structures, if they do not + * already have a SV_COUNTER shadow variable, then attach a + * new one. + */ + shadow_count = klp_shadow_get_or_alloc(d, SV_COUNTER, + sizeof(*shadow_count), GFP_NOWAIT, + NULL, NULL); + if (shadow_count) + *shadow_count += 1; + + return time_after(jiffies, d->jiffies_expire); +} + +static void livepatch_fix2_dummy_leak_dtor(void *obj, void *shadow_data) +{ + void *d = obj; + int **shadow_leak = shadow_data; + + pr_info("%s: dummy @ %p, prevented leak @ %p\n", + __func__, d, *shadow_leak); + kfree(*shadow_leak); +} + +static void livepatch_fix2_dummy_free(struct dummy *d) +{ + int **shadow_leak; + int *shadow_count; + + /* Patch: copy the memory leak patch from the fix1 module. */ + shadow_leak = klp_shadow_get(d, SV_LEAK); + if (shadow_leak) + klp_shadow_free(d, SV_LEAK, livepatch_fix2_dummy_leak_dtor); + else + pr_info("%s: dummy @ %p leaked!\n", __func__, d); + + /* + * Patch: fetch the SV_COUNTER shadow variable and display + * the final count. Detach the shadow variable. + */ + shadow_count = klp_shadow_get(d, SV_COUNTER); + if (shadow_count) { + pr_info("%s: dummy @ %p, check counter = %d\n", + __func__, d, *shadow_count); + klp_shadow_free(d, SV_COUNTER, NULL); + } + + kfree(d); +} + +static struct klp_func funcs[] = { + { + .old_name = "dummy_check", + .new_func = livepatch_fix2_dummy_check, + }, + { + .old_name = "dummy_free", + .new_func = livepatch_fix2_dummy_free, + }, { } +}; + +static struct klp_object objs[] = { + { + .name = "livepatch_shadow_mod", + .funcs = funcs, + }, { } +}; + +static struct klp_patch patch = { + .mod = THIS_MODULE, + .objs = objs, +}; + +static int livepatch_shadow_fix2_init(void) +{ + return klp_enable_patch(&patch); +} + +static void livepatch_shadow_fix2_exit(void) +{ + /* Cleanup any existing SV_COUNTER shadow variables */ + klp_shadow_free_all(SV_COUNTER, NULL); +} + +module_init(livepatch_shadow_fix2_init); +module_exit(livepatch_shadow_fix2_exit); +MODULE_DESCRIPTION("Live patching demo for shadow variables"); +MODULE_LICENSE("GPL"); +MODULE_INFO(livepatch, "Y"); |
