From e873c74132f0c5f1452816cd9bb26208f0bba1e1 Mon Sep 17 00:00:00 2001 From: Shivank Garg Date: Sat, 22 Aug 2026 19:22:05 +0000 Subject: dmaengine: fix use-after-free in dma_chan_put() and dma_release_channel() When dma_device_put() drops the last reference on chan->device->ref, dma_device_release() runs and may free the dma_device along with its channels. dma_chan_put() then still reads chan->device->owner via dma_chan_to_owner() for the trailing module_put(). KASAN catches it: slab-use-after-free in dma_chan_put+0x3e6/0x4c0 Read of size 8 by task insmod/6319 Freed by task 6319: kfree+0x225/0x470 dma_chan_put+0x395/0x4c0 dmaengine_put+0xf8/0x160 Cache the module owner in dma_chan_put() before the put so the trailing module_put() does not need chan->device. Fixes: 8ad342a86359 ("dmaengine: Add reference counting to dma_device struct") Suggested-by: Sashiko Link: https://sashiko.dev/#/patchset/20260518-dmaengine-kref-fix-v1-1-4d6125048fb7@amd.com Reviewed-by: Frank Li Reviewed-by: Logan Gunthorpe Signed-off-by: Shivank Garg Link: https://patch.msgid.link/20260822-dmaengine-kref-fix-v5-3-d4a4ee47d927@amd.com Signed-off-by: Vinod Koul --- include/net/cls_cgroup.h | 88 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 88 insertions(+) create mode 100644 include/net/cls_cgroup.h (limited to 'include/net/cls_cgroup.h') diff --git a/include/net/cls_cgroup.h b/include/net/cls_cgroup.h new file mode 100644 index 000000000..668aeee9b --- /dev/null +++ b/include/net/cls_cgroup.h @@ -0,0 +1,88 @@ +/* SPDX-License-Identifier: GPL-2.0-or-later */ +/* + * cls_cgroup.h Control Group Classifier + * + * Authors: Thomas Graf + */ + +#ifndef _NET_CLS_CGROUP_H +#define _NET_CLS_CGROUP_H + +#include +#include +#include +#include +#include + +#ifdef CONFIG_CGROUP_NET_CLASSID +struct cgroup_cls_state { + struct cgroup_subsys_state css; + u32 classid; +}; + +struct cgroup_cls_state *task_cls_state(struct task_struct *p); + +static inline u32 task_cls_classid(struct task_struct *p) +{ + u32 classid; + + if (in_interrupt()) + return 0; + + rcu_read_lock(); + classid = container_of(task_css(p, net_cls_cgrp_id), + struct cgroup_cls_state, css)->classid; + rcu_read_unlock(); + + return classid; +} + +static inline void sock_update_classid(struct sock_cgroup_data *skcd) +{ + u32 classid; + + classid = task_cls_classid(current); + sock_cgroup_set_classid(skcd, classid); +} + +static inline u32 __task_get_classid(struct task_struct *task) +{ + return task_cls_state(task)->classid; +} + +static inline u32 task_get_classid(const struct sk_buff *skb) +{ + u32 classid = __task_get_classid(current); + + /* Due to the nature of the classifier it is required to ignore all + * packets originating from softirq context as accessing `current' + * would lead to false results. + * + * This test assumes that all callers of dev_queue_xmit() explicitly + * disable bh. Knowing this, it is possible to detect softirq based + * calls by looking at the number of nested bh disable calls because + * softirqs always disables bh. + */ + if (softirq_count()) { + struct sock *sk = skb_to_full_sk(skb); + + /* If there is an sock_cgroup_classid we'll use that. */ + if (!sk || !sk_fullsock(sk)) + return 0; + + classid = sock_cgroup_classid(&sk->sk_cgrp_data); + } + + return classid; +} +#else /* !CONFIG_CGROUP_NET_CLASSID */ +static inline void sock_update_classid(struct sock_cgroup_data *skcd) +{ +} + +static inline u32 task_get_classid(const struct sk_buff *skb) +{ + return 0; +} +#endif /* CONFIG_CGROUP_NET_CLASSID */ +#endif /* _NET_CLS_CGROUP_H */ -- cgit v1.3.1