This is a note to let you know that I've just added the patch titled
kernfs: fix missing kernfs_iattr_rwsem locking
to the 6.5-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
kernfs-fix-missing-kernfs_iattr_rwsem-locking.patch
and it can be found in the queue-6.5 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 0559f63057f927d298d68294d6ff77ce09b99255 Mon Sep 17 00:00:00 2001
From: Ian Kent <raven@xxxxxxxxxx>
Date: Sun, 6 Aug 2023 09:26:49 +0800
Subject: kernfs: fix missing kernfs_iattr_rwsem locking
From: Ian Kent <raven@xxxxxxxxxx>
commit 0559f63057f927d298d68294d6ff77ce09b99255 upstream.
When the kernfs_iattr_rwsem was introduced a case was missed.
The update of the kernfs directory node child count was also protected
by the kernfs_rwsem and needs to be included in the change so that the
child count (and so the inode n_link attribute) does not change while
holding the rwsem for read.
Fixes: 9caf69614225 ("kernfs: Introduce separate rwsem to protect inode attributes.")
Cc: stable <stable@xxxxxxxxxx>
Signed-off-by: Ian Kent <raven@xxxxxxxxxx>
Reviewed-By: Imran Khan <imran.f.khan@xxxxxxxxxx>
Acked-by: Miklos Szeredi <mszeredi@xxxxxxxxxx>
Cc: Anders Roxell <anders.roxell@xxxxxxxxxx>
Cc: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Cc: Eric Sandeen <sandeen@xxxxxxxxxxx>
Link: https://lore.kernel.org/r/169128520941.68052.15749253469930138901.stgit@xxxxxxxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
fs/kernfs/dir.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
index 5a1a4af9d3d2..bf243015834e 100644
--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c
@@ -383,9 +383,11 @@ static int kernfs_link_sibling(struct kernfs_node *kn)
rb_insert_color(&kn->rb, &kn->parent->dir.children);
/* successfully added, account subdir number */
+ down_write(&kernfs_root(kn)->kernfs_iattr_rwsem);
if (kernfs_type(kn) == KERNFS_DIR)
kn->parent->dir.subdirs++;
kernfs_inc_rev(kn->parent);
+ up_write(&kernfs_root(kn)->kernfs_iattr_rwsem);
return 0;
}
@@ -408,9 +410,11 @@ static bool kernfs_unlink_sibling(struct kernfs_node *kn)
if (RB_EMPTY_NODE(&kn->rb))
return false;
+ down_write(&kernfs_root(kn)->kernfs_iattr_rwsem);
if (kernfs_type(kn) == KERNFS_DIR)
kn->parent->dir.subdirs--;
kernfs_inc_rev(kn->parent);
+ up_write(&kernfs_root(kn)->kernfs_iattr_rwsem);
rb_erase(&kn->rb, &kn->parent->dir.children);
RB_CLEAR_NODE(&kn->rb);
--
2.42.0
Patches currently in stable-queue which might be from raven@xxxxxxxxxx are
queue-6.5/kernfs-fix-missing-kernfs_iattr_rwsem-locking.patch
