From cc798c83898ea0a77fcaa1a92afda35c3c3ded74 Mon Sep 17 00:00:00 2001
From: Andrea Arcangeli <aarcange@redhat.com>
Date: Mon, 5 Aug 2019 10:34:04 -0700
Subject: [PATCH] kernfs: fix memleak in kernel_ops_readdir()
If getdents64 is killed or hits on segfault, it'll leave cgroups
directories in sysfs pinned leaking memory because the kernfs node
won't be freed on rmdir and the parent neither.
Repro:
# for i in `seq 1000`; do mkdir $i; done
# rmdir *
# for i in `seq 1000`; do mkdir $i; done
# rmdir *
# for i in `seq 1000`; do while :; do ls $i/ >/dev/null; done & done
# while :; do killall ls; done
kernfs_node_cache in /proc/slabinfo keeps going up as expected.
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: stable@vger.kernel.org # goes way back to original sysfs days
Link: https://lore.kernel.org/r/20190805173404.GF136335@devbig004.ftw2.facebook.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/kernfs/dir.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
index a387534c95778..1e98efc2bf6d8 100644
--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c
@@ -1684,11 +1684,14 @@ static int kernfs_fop_readdir(struct file *file, struct dir_context *ctx)
kernfs_get(pos);
mutex_unlock(&kernfs_mutex);
- if (!dir_emit(ctx, name, len, ino, type))
- return 0;
+ if (unlikely(!dir_emit(ctx, name, len, ino, type))) {
+ kernfs_put(pos);
+ goto out;
+ }
mutex_lock(&kernfs_mutex);
}
mutex_unlock(&kernfs_mutex);
+out:
file->private_data = NULL;
ctx->pos = INT_MAX;
return 0;
--
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