This is a note to let you know that I've just added the patch titled nfc: nfcsim: fix use after free during module unload to the 5.13-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: nfc-nfcsim-fix-use-after-free-during-module-unload.patch and it can be found in the queue-5.13 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 5e7b30d24a5b8cb691c173b45b50e3ca0191be19 Mon Sep 17 00:00:00 2001 From: Krzysztof Kozlowski <krzysztof.kozlowski@xxxxxxxxxxxxx> Date: Wed, 28 Jul 2021 08:49:09 +0200 Subject: nfc: nfcsim: fix use after free during module unload MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Krzysztof Kozlowski <krzysztof.kozlowski@xxxxxxxxxxxxx> commit 5e7b30d24a5b8cb691c173b45b50e3ca0191be19 upstream. There is a use after free memory corruption during module exit: - nfcsim_exit() - nfcsim_device_free(dev0) - nfc_digital_unregister_device() This iterates over command queue and frees all commands, - dev->up = false - nfcsim_link_shutdown() - nfcsim_link_recv_wake() This wakes the sleeping thread nfcsim_link_recv_skb(). - nfcsim_link_recv_skb() Wake from wait_event_interruptible_timeout(), call directly the deb->cb callback even though (dev->up == false), - digital_send_cmd_complete() Dereference of "struct digital_cmd" cmd which was freed earlier by nfc_digital_unregister_device(). This causes memory corruption shortly after (with unrelated stack trace): nfc nfc0: NFC: nfcsim_recv_wq: Device is down llcp: nfc_llcp_recv: err -19 nfc nfc1: NFC: nfcsim_recv_wq: Device is down BUG: unable to handle page fault for address: ffffffffffffffed Call Trace: fsnotify+0x54b/0x5c0 __fsnotify_parent+0x1fe/0x300 ? vfs_write+0x27c/0x390 vfs_write+0x27c/0x390 ksys_write+0x63/0xe0 do_syscall_64+0x3b/0x90 entry_SYSCALL_64_after_hwframe+0x44/0xae KASAN report: BUG: KASAN: use-after-free in digital_send_cmd_complete+0x16/0x50 Write of size 8 at addr ffff88800a05f720 by task kworker/0:2/71 Workqueue: events nfcsim_recv_wq [nfcsim] Call Trace: dump_stack_lvl+0x45/0x59 print_address_description.constprop.0+0x21/0x140 ? digital_send_cmd_complete+0x16/0x50 ? digital_send_cmd_complete+0x16/0x50 kasan_report.cold+0x7f/0x11b ? digital_send_cmd_complete+0x16/0x50 ? digital_dep_link_down+0x60/0x60 digital_send_cmd_complete+0x16/0x50 nfcsim_recv_wq+0x38f/0x3d5 [nfcsim] ? nfcsim_in_send_cmd+0x4a/0x4a [nfcsim] ? lock_is_held_type+0x98/0x110 ? finish_wait+0x110/0x110 ? rcu_read_lock_sched_held+0x9c/0xd0 ? rcu_read_lock_bh_held+0xb0/0xb0 ? lockdep_hardirqs_on_prepare+0x12e/0x1f0 This flow of calling digital_send_cmd_complete() callback on driver exit is specific to nfcsim which implements reading and sending work queues. Since the NFC digital device was unregistered, the callback should not be called. Fixes: 204bddcb508f ("NFC: nfcsim: Make use of the Digital layer") Cc: <stable@xxxxxxxxxxxxxxx> Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@xxxxxxxxxxxxx> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/nfc/nfcsim.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) --- a/drivers/nfc/nfcsim.c +++ b/drivers/nfc/nfcsim.c @@ -192,8 +192,7 @@ static void nfcsim_recv_wq(struct work_s if (!IS_ERR(skb)) dev_kfree_skb(skb); - - skb = ERR_PTR(-ENODEV); + return; } dev->cb(dev->nfc_digital_dev, dev->arg, skb); Patches currently in stable-queue which might be from krzysztof.kozlowski@xxxxxxxxxxxxx are queue-5.13/nfc-nfcsim-fix-use-after-free-during-module-unload.patch