This is a note to let you know that I've just added the patch titled
xen/blkback: don't free be structure too early
to the 4.4-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:
xen-blkback-don-t-free-be-structure-too-early.patch
and it can be found in the queue-4.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 71df1d7ccad1c36f7321d6b3b48f2ea42681c363 Mon Sep 17 00:00:00 2001
From: Juergen Gross <jgross@xxxxxxxx>
Date: Thu, 18 May 2017 17:28:48 +0200
Subject: xen/blkback: don't free be structure too early
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From: Juergen Gross <jgross@xxxxxxxx>
commit 71df1d7ccad1c36f7321d6b3b48f2ea42681c363 upstream.
The be structure must not be freed when freeing the blkif structure
isn't done. Otherwise a use-after-free of be when unmapping the ring
used for communicating with the frontend will occur in case of a
late call of xenblk_disconnect() (e.g. due to an I/O still active
when trying to disconnect).
Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
Tested-by: Steven Haigh <netwiz@xxxxxxxxx>
Acked-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/block/xen-blkback/xenbus.c | 7 +++----
1 file changed, 3 insertions(+), 4 deletions(-)
--- a/drivers/block/xen-blkback/xenbus.c
+++ b/drivers/block/xen-blkback/xenbus.c
@@ -266,9 +266,10 @@ static int xen_blkif_disconnect(struct x
static void xen_blkif_free(struct xen_blkif *blkif)
{
-
- xen_blkif_disconnect(blkif);
+ WARN_ON(xen_blkif_disconnect(blkif));
xen_vbd_free(&blkif->vbd);
+ kfree(blkif->be->mode);
+ kfree(blkif->be);
/* Make sure everything is drained before shutting down */
BUG_ON(blkif->persistent_gnt_c != 0);
@@ -445,8 +446,6 @@ static int xen_blkbk_remove(struct xenbu
xen_blkif_put(be->blkif);
}
- kfree(be->mode);
- kfree(be);
return 0;
}
Patches currently in stable-queue which might be from jgross@xxxxxxxx are
queue-4.4/xen-blkback-don-t-free-be-structure-too-early.patch
queue-4.4/xen-blkback-don-t-use-xen_blkif_get-in-xen-blkback-kthread.patch