The quilt patch titled
Subject: mm: shrinkers: fix double kfree on shrinker name
has been removed from the -mm tree. Its filename was
mm-shrinkers-fix-double-kfree-on-shrinker-name.patch
This patch was dropped because it was merged into the mm-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
------------------------------------------------------
From: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
Subject: mm: shrinkers: fix double kfree on shrinker name
Date: Wed, 20 Jul 2022 23:47:55 +0900
syzbot is reporting double kfree() at free_prealloced_shrinker() [1], for
destroy_unused_super() calls free_prealloced_shrinker() even if
prealloc_shrinker() returned an error. Explicitly clear shrinker name
when prealloc_shrinker() called kfree().
[roman.gushchin@xxxxxxxxx: zero shrinker->name in all cases where shrinker->name is freed]
Link: https://lkml.kernel.org/r/YtgteTnQTgyuKUSY@castle
Link: https://syzkaller.appspot.com/bug?extid=8b481578352d4637f510 [1]
Link: https://lkml.kernel.org/r/ffa62ece-6a42-2644-16cf-0d33ef32c676@xxxxxxxxxxxxxxxxxxx
Fixes: e33c267ab70de424 ("mm: shrinkers: provide shrinkers with names")
Reported-by: syzbot <syzbot+8b481578352d4637f510@xxxxxxxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
Acked-by: Roman Gushchin <roman.gushchin@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/shrinker_debug.c | 1 +
mm/vmscan.c | 9 +++++++--
2 files changed, 8 insertions(+), 2 deletions(-)
--- a/mm/shrinker_debug.c~mm-shrinkers-fix-double-kfree-on-shrinker-name
+++ a/mm/shrinker_debug.c
@@ -251,6 +251,7 @@ void shrinker_debugfs_remove(struct shri
lockdep_assert_held(&shrinker_rwsem);
kfree_const(shrinker->name);
+ shrinker->name = NULL;
if (!shrinker->debugfs_entry)
return;
--- a/mm/vmscan.c~mm-shrinkers-fix-double-kfree-on-shrinker-name
+++ a/mm/vmscan.c
@@ -644,8 +644,10 @@ int prealloc_shrinker(struct shrinker *s
return -ENOMEM;
err = __prealloc_shrinker(shrinker);
- if (err)
+ if (err) {
kfree_const(shrinker->name);
+ shrinker->name = NULL;
+ }
return err;
}
@@ -660,6 +662,7 @@ void free_prealloced_shrinker(struct shr
{
#ifdef CONFIG_SHRINKER_DEBUG
kfree_const(shrinker->name);
+ shrinker->name = NULL;
#endif
if (shrinker->flags & SHRINKER_MEMCG_AWARE) {
down_write(&shrinker_rwsem);
@@ -704,8 +707,10 @@ int register_shrinker(struct shrinker *s
return -ENOMEM;
err = __register_shrinker(shrinker);
- if (err)
+ if (err) {
kfree_const(shrinker->name);
+ shrinker->name = NULL;
+ }
return err;
}
#else
_
Patches currently in -mm which might be from penguin-kernel@xxxxxxxxxxxxxxxxxxx are
