This is a note to let you know that I've just added the patch titled cfg80211: check rdev resume callback only for registered wiphy to the 4.9-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: cfg80211-check-rdev-resume-callback-only-for-registered-wiphy.patch and it can be found in the queue-4.9 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From b3ef5520c1eabb56064474043c7c55a1a65b8708 Mon Sep 17 00:00:00 2001 From: Arend Van Spriel <arend.vanspriel@xxxxxxxxxxxx> Date: Tue, 28 Mar 2017 09:11:31 +0100 Subject: cfg80211: check rdev resume callback only for registered wiphy From: Arend Van Spriel <arend.vanspriel@xxxxxxxxxxxx> commit b3ef5520c1eabb56064474043c7c55a1a65b8708 upstream. We got the following use-after-free KASAN report: BUG: KASAN: use-after-free in wiphy_resume+0x591/0x5a0 [cfg80211] at addr ffff8803fc244090 Read of size 8 by task kworker/u16:24/2587 CPU: 6 PID: 2587 Comm: kworker/u16:24 Tainted: G B 4.9.13-debug+ Hardware name: Dell Inc. XPS 15 9550/0N7TVV, BIOS 1.2.19 12/22/2016 Workqueue: events_unbound async_run_entry_fn ffff880425d4f9d8 ffffffffaeedb541 ffff88042b80ef00 ffff8803fc244088 ffff880425d4fa00 ffffffffae84d7a1 ffff880425d4fa98 ffff8803fc244080 ffff88042b80ef00 ffff880425d4fa88 ffffffffae84da3a ffffffffc141f7d9 Call Trace: [<ffffffffaeedb541>] dump_stack+0x85/0xc4 [<ffffffffae84d7a1>] kasan_object_err+0x21/0x70 [<ffffffffae84da3a>] kasan_report_error+0x1fa/0x500 [<ffffffffc141f7d9>] ? cfg80211_bss_age+0x39/0xc0 [cfg80211] [<ffffffffc141f83a>] ? cfg80211_bss_age+0x9a/0xc0 [cfg80211] [<ffffffffae48d46d>] ? trace_hardirqs_on+0xd/0x10 [<ffffffffc13fb1c0>] ? wiphy_suspend+0xc70/0xc70 [cfg80211] [<ffffffffae84def1>] __asan_report_load8_noabort+0x61/0x70 [<ffffffffc13fb100>] ? wiphy_suspend+0xbb0/0xc70 [cfg80211] [<ffffffffc13fb751>] ? wiphy_resume+0x591/0x5a0 [cfg80211] [<ffffffffc13fb751>] wiphy_resume+0x591/0x5a0 [cfg80211] [<ffffffffc13fb1c0>] ? wiphy_suspend+0xc70/0xc70 [cfg80211] [<ffffffffaf3b206e>] dpm_run_callback+0x6e/0x4f0 [<ffffffffaf3b31b2>] device_resume+0x1c2/0x670 [<ffffffffaf3b367d>] async_resume+0x1d/0x50 [<ffffffffae3ee84e>] async_run_entry_fn+0xfe/0x610 [<ffffffffae3d0666>] process_one_work+0x716/0x1a50 [<ffffffffae3d05c9>] ? process_one_work+0x679/0x1a50 [<ffffffffafdd7b6d>] ? _raw_spin_unlock_irq+0x3d/0x60 [<ffffffffae3cff50>] ? pwq_dec_nr_in_flight+0x2b0/0x2b0 [<ffffffffae3d1a80>] worker_thread+0xe0/0x1460 [<ffffffffae3d19a0>] ? process_one_work+0x1a50/0x1a50 [<ffffffffae3e54c2>] kthread+0x222/0x2e0 [<ffffffffae3e52a0>] ? kthread_park+0x80/0x80 [<ffffffffae3e52a0>] ? kthread_park+0x80/0x80 [<ffffffffae3e52a0>] ? kthread_park+0x80/0x80 [<ffffffffafdd86aa>] ret_from_fork+0x2a/0x40 Object at ffff8803fc244088, in cache kmalloc-1024 size: 1024 Allocated: PID = 71 save_stack_trace+0x1b/0x20 save_stack+0x46/0xd0 kasan_kmalloc+0xad/0xe0 kasan_slab_alloc+0x12/0x20 __kmalloc_track_caller+0x134/0x360 kmemdup+0x20/0x50 brcmf_cfg80211_attach+0x10b/0x3a90 [brcmfmac] brcmf_bus_start+0x19a/0x9a0 [brcmfmac] brcmf_pcie_setup+0x1f1a/0x3680 [brcmfmac] brcmf_fw_request_nvram_done+0x44c/0x11b0 [brcmfmac] request_firmware_work_func+0x135/0x280 process_one_work+0x716/0x1a50 worker_thread+0xe0/0x1460 kthread+0x222/0x2e0 ret_from_fork+0x2a/0x40 Freed: PID = 2568 save_stack_trace+0x1b/0x20 save_stack+0x46/0xd0 kasan_slab_free+0x71/0xb0 kfree+0xe8/0x2e0 brcmf_cfg80211_detach+0x62/0xf0 [brcmfmac] brcmf_detach+0x14a/0x2b0 [brcmfmac] brcmf_pcie_remove+0x140/0x5d0 [brcmfmac] brcmf_pcie_pm_leave_D3+0x198/0x2e0 [brcmfmac] pci_pm_resume+0x186/0x220 dpm_run_callback+0x6e/0x4f0 device_resume+0x1c2/0x670 async_resume+0x1d/0x50 async_run_entry_fn+0xfe/0x610 process_one_work+0x716/0x1a50 worker_thread+0xe0/0x1460 kthread+0x222/0x2e0 ret_from_fork+0x2a/0x40 Memory state around the buggy address: ffff8803fc243f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc ffff8803fc244000: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc >ffff8803fc244080: fc fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff8803fc244100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8803fc244180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb What is happening is that brcmf_pcie_resume() detects a device that is no longer responsive and it decides to unbind resulting in a wiphy_unregister() and wiphy_free() call. Now the wiphy instance remains allocated, because PM needs to call wiphy_resume() for it. However, brcmfmac already does a kfree() for the struct cfg80211_registered_device::ops field. Change the checks in wiphy_resume() to only access the struct cfg80211_registered_device::ops if the wiphy instance is still registered at this time. Reported-by: Daniel J Blueman <daniel@xxxxxxxxx> Reviewed-by: Hante Meuleman <hante.meuleman@xxxxxxxxxxxx> Reviewed-by: Pieter-Paul Giesberts <pieter-paul.giesberts@xxxxxxxxxxxx> Reviewed-by: Franky Lin <franky.lin@xxxxxxxxxxxx> Signed-off-by: Arend van Spriel <arend.vanspriel@xxxxxxxxxxxx> Signed-off-by: Johannes Berg <johannes.berg@xxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- net/wireless/sysfs.c | 10 ++++------ 1 file changed, 4 insertions(+), 6 deletions(-) --- a/net/wireless/sysfs.c +++ b/net/wireless/sysfs.c @@ -130,12 +130,10 @@ static int wiphy_resume(struct device *d /* Age scan results with time spent in suspend */ cfg80211_bss_age(rdev, get_seconds() - rdev->suspend_at); - if (rdev->ops->resume) { - rtnl_lock(); - if (rdev->wiphy.registered) - ret = rdev_resume(rdev); - rtnl_unlock(); - } + rtnl_lock(); + if (rdev->wiphy.registered && rdev->ops->resume) + ret = rdev_resume(rdev); + rtnl_unlock(); return ret; } Patches currently in stable-queue which might be from arend.vanspriel@xxxxxxxxxxxx are queue-4.9/cfg80211-check-rdev-resume-callback-only-for-registered-wiphy.patch