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Commit cc798c83 authored by Andrea Arcangeli's avatar Andrea Arcangeli Committed by Greg Kroah-Hartman
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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: default avatarAndrea Arcangeli <aarcange@redhat.com>
Signed-off-by: default avatarTejun 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: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent ac43432c

fs/kernfs/dir.c

+5 −2
Original line number Diff line number Diff line
@@ -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;