The patch titled
Subject: mm: zswap: fix objcg use-after-free in entry destruction
has been added to the -mm mm-hotfixes-unstable branch. Its filename is
mm-zswap-fix-objcg-use-after-free-in-entry-destruction.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-zswap-fix-objcg-use-after-free-in-entry-destruction.patch
This patch will later appear in the mm-hotfixes-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Johannes Weiner <hannes@xxxxxxxxxxx>
Subject: mm: zswap: fix objcg use-after-free in entry destruction
Date: Mon, 29 Jan 2024 20:34:38 -0500
In the per-memcg LRU universe, LRU removal uses entry->objcg to determine
which list count needs to be decreased. Drop the objcg reference after
updating the LRU, to fix a possible use-after-free.
Link: https://lkml.kernel.org/r/20240130013438.565167-1-hannes@xxxxxxxxxxx
Fixes: a65b0e7607cc ("zswap: make shrinking memcg-aware")
Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Acked-by: Yosry Ahmed <yosryahmed@xxxxxxxxxx>
Cc: Chengming Zhou <zhouchengming@xxxxxxxxxxxxx>
Cc: Nhat Pham <nphamcs@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/zswap.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
--- a/mm/zswap.c~mm-zswap-fix-objcg-use-after-free-in-entry-destruction
+++ a/mm/zswap.c
@@ -536,10 +536,6 @@ static struct zpool *zswap_find_zpool(st
*/
static void zswap_free_entry(struct zswap_entry *entry)
{
- if (entry->objcg) {
- obj_cgroup_uncharge_zswap(entry->objcg, entry->length);
- obj_cgroup_put(entry->objcg);
- }
if (!entry->length)
atomic_dec(&zswap_same_filled_pages);
else {
@@ -548,6 +544,10 @@ static void zswap_free_entry(struct zswa
atomic_dec(&entry->pool->nr_stored);
zswap_pool_put(entry->pool);
}
+ if (entry->objcg) {
+ obj_cgroup_uncharge_zswap(entry->objcg, entry->length);
+ obj_cgroup_put(entry->objcg);
+ }
zswap_entry_cache_free(entry);
atomic_dec(&zswap_stored_pages);
zswap_update_total_size();
_
Patches currently in -mm which might be from hannes@xxxxxxxxxxx are
mm-zswap-fix-objcg-use-after-free-in-entry-destruction.patch
mm-zswap-rename-zswap_free_entry-to-zswap_entry_free.patch
mm-zswap-inline-and-remove-zswap_entry_find_get.patch
mm-zswap-move-zswap_invalidate_entry-to-related-functions.patch
mm-zswap-warn-when-referencing-a-dead-entry.patch
mm-zswap-clean-up-zswap_entry_put.patch
mm-zswap-rename-__zswap_load-to-zswap_decompress.patch
mm-zswap-break-out-zwap_compress.patch
mm-zswap-further-cleanup-zswap_store.patch
mm-zswap-simplify-zswap_invalidate.patch
mm-zswap-function-ordering-pool-alloc-free.patch
mm-zswap-function-ordering-pool-refcounting.patch
mm-zswap-function-ordering-zswap_pools.patch
mm-zswap-function-ordering-pool-params.patch
mm-zswap-function-ordering-public-lru-api.patch
mm-zswap-function-ordering-move-entry-sections-out-of-lru-section.patch
mm-zswap-function-ordering-move-entry-section-out-of-tree-section.patch
mm-zswap-function-ordering-compress-decompress-functions.patch
mm-zswap-function-ordering-per-cpu-compression-infra.patch
mm-zswap-function-ordering-writeback.patch
mm-zswap-function-ordering-shrink_memcg_cb.patch
