Xen Security Advisory 457 v1 - Linux/xen-netback: Memory leak due to missing cleanup function
Xen.org security team <[email protected]> Tue, 07 May 2024 17:12:54 +0000
| Newsgroups | gmane.comp.emulators.xen.announce |
|---|---|
| Message-ID | <E1s4ON4-0002CG-9R__23663.1396853895$1715102099$gmane$org@xenbits.xenproject.org> |
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Xen Security Advisory XSA-457
Linux/xen-netback: Memory leak due to missing cleanup function
ISSUE DESCRIPTION
=================
In netback, xennet_alloc_one_rx_buffer() failed to call the
appropriate clean-up function, resulting in a memory leak.
IMPACT
======
A malicious guest userspace process can exhaust memory resources
within the guest kernel, potentially leading to a system crash (Denial
of Service). It is not known whether it can be triggered remotely.
VULNERABLE SYSTEMS
==================
Systems with guests running Linux 5.9 and later with Xen PV network
devices are affected.
MITIGATION
==========
For HVM guests, using emulated network devices will avoid this issue.
RESOLUTION
==========
The following patch in Linux resolves the issue:
https://git.kernel.org/torvalds/c/037965402a010898d34f4e35327d22c0a95cd51f
A copy of which has attached.
xsa457.patch Linux 5.9
$ sha256sum xsa457*
9d6ae3da27f1ff92f9f45c800822beecda603d6dea6726207cee6c768416114c xsa457.patch
$
NOTE ON THE LACK OF EMBARGO
===========================
The issue was reported initially on a public bug tracker and fixed in
public before it was realized that there was a security aspect.
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xsa457.patch
(application/octet-stream, 1.9 KB)
From 037965402a010898d34f4e35327d22c0a95cd51f Mon Sep 17 00:00:00 2001 From: Jesper Dangaard Brouer <[email protected]> Date: Wed, 27 Mar 2024 13:14:56 +0100 Subject: xen-netfront: Add missing skb_mark_for_recycle Notice that skb_mark_for_recycle() is introduced later than fixes tag in commit 6a5bcd84e886 ("page_pool: Allow drivers to hint on SKB recycling"). It is believed that fixes tag were missing a call to page_pool_release_page() between v5.9 to v5.14, after which is should have used skb_mark_for_recycle(). Since v6.6 the call page_pool_release_page() were removed (in commit 535b9c61bdef ("net: page_pool: hide page_pool_release_page()") and remaining callers converted (in commit 6bfef2ec0172 ("Merge branch 'net-page_pool-remove-page_pool_release_page'")). This leak became visible in v6.8 via commit dba1b8a7ab68 ("mm/page_pool: catch page_pool memory leaks"). Cc: [email protected] Fixes: 6c5aa6fc4def ("xen networking: add basic XDP support for xen-netfront") Reported-by: Leonidas Spyropoulos <[email protected]> Link: https://bugzilla.kernel.org/show_bug.cgi?id=218654 Reported-by: Arthur Borsboom <[email protected]> Signed-off-by: Jesper Dangaard Brouer <[email protected]> Link: https://lore.kernel.org/r/171154167446.2671062.9127105384591237363.stgit@firesoul Signed-off-by: Jakub Kicinski <[email protected]> --- drivers/net/xen-netfront.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/net/xen-netfront.c b/drivers/net/xen-netfront.c index ad29f370034e4f..8d2aee88526c69 100644 --- a/drivers/net/xen-netfront.c +++ b/drivers/net/xen-netfront.c @@ -285,6 +285,7 @@ static struct sk_buff *xennet_alloc_one_rx_buffer(struct netfront_queue *queue) return NULL; } skb_add_rx_frag(skb, 0, page, 0, 0, PAGE_SIZE); + skb_mark_for_recycle(skb); /* Align ip header to a 16 bytes boundary */ skb_reserve(skb, NET_IP_ALIGN); -- cgit 1.2.3-korg