Blame SOURCES/CVE-2021-32399.patch

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From d50512e6312824861ce342eb68bb1eb7dea984e2 Mon Sep 17 00:00:00 2001
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From: Artem Savkov <asavkov@redhat.com>
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Date: Mon, 21 Jun 2021 12:09:28 +0200
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Subject: [PATCH] bluetooth: eliminate the potential race condition when
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 removing the HCI controller
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Kernels:
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4.18.0-305.el8
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4.18.0-305.3.1.el8_4
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4.18.0-305.7.1.el8_4
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Changes since last build:
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[x86_64]:
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hci_request.o: changed function: hci_req_sync
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[ppc64le]:
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hci_request.o: changed function: bg_scan_update
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hci_request.o: changed function: connectable_update_work
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hci_request.o: changed function: discov_off
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hci_request.o: changed function: discov_update
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hci_request.o: changed function: discoverable_update_work
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hci_request.o: changed function: hci_req_sync
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hci_request.o: changed function: le_scan_disable_work
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hci_request.o: changed function: le_scan_restart_work
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hci_request.o: changed function: scan_update_work
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---------------------------
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Kernels:
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4.18.0-305.el8
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4.18.0-305.3.1.el8_4
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4.18.0-305.7.1.el8_4
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Modifications: none
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Z-MR: https://gitlab.com/redhat/rhel/src/kernel/rhel-8/-/merge_requests/804
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commit 84466ca3bdf0d5d77d4c8a851336406627de2628
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Author: Gopal Tiwari <gtiwari@redhat.com>
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Date:   Mon Jun 14 13:47:30 2021 +0530
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    bluetooth: eliminate the potential race condition when removing the HCI controller
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    Bugzilla: https://bugzilla.redhat.com/1971464
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    CVE: CVE-2021-32399
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    Y-Commit: 54c81477df19422cbc3c8cf3b555159ff642f15b
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    O-Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1971488
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    Upstream: Merged
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    Testing: Sanity_only.
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    commit e2cb6b891ad2b8caa9131e3be70f45243df82a80
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    Author: Lin Ma <linma@zju.edu.cn>
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    Date:   Mon Apr 12 19:17:57 2021 +0800
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    bluetooth: eliminate the potential race condition when removing the HCI controller
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    There is a possible race condition vulnerability between issuing a HCI
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    command and removing the cont.  Specifically, functions hci_req_sync()
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    and hci_dev_do_close() can race each other like below:
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    thread-A in hci_req_sync()      |   thread-B in hci_dev_do_close()
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                                    |   hci_req_sync_lock(hdev);
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    test_bit(HCI_UP, &hdev->flags); |
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    ...                             |   test_and_clear_bit(HCI_UP, &hdev->flags)
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    hci_req_sync_lock(hdev);        |
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                                    |
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    In this commit we alter the sequence in function hci_req_sync(). Hence,
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    the thread-A cannot issue th.
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    Signed-off-by: Lin Ma <linma@zju.edu.cn>
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    Cc: Marcel Holtmann <marcel@holtmann.org>
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    Fixes: 7c6a329e4447 ("[Bluetooth] Fix regression from using default link policy")
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    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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    (cherry picked from commit e2cb6b891ad2b8caa9131e3be70f45243df82a80)
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    Signed-off-by: Gopal Tiwari <gtiwari@redhat.com>
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    Signed-off-by: Jan Stancek <jstancek@redhat.com>
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Signed-off-by: Artem Savkov <asavkov@redhat.com>
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Acked-by: Yannick Cote <ycote@redhat.com>
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Acked-by: Joe Lawrence <joe.lawrence@redhat.com>
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---
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 net/bluetooth/hci_request.c | 12 ++++++++----
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 1 file changed, 8 insertions(+), 4 deletions(-)
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diff --git a/net/bluetooth/hci_request.c b/net/bluetooth/hci_request.c
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index cf1b42ec40af97..ca9088d439460e 100644
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--- a/net/bluetooth/hci_request.c
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+++ b/net/bluetooth/hci_request.c
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@@ -274,12 +274,16 @@ int hci_req_sync(struct hci_dev *hdev, int (*req)(struct hci_request *req,
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 {
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 	int ret;
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-	if (!test_bit(HCI_UP, &hdev->flags))
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-		return -ENETDOWN;
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-
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 	/* Serialize all requests */
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 	hci_req_sync_lock(hdev);
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-	ret = __hci_req_sync(hdev, req, opt, timeout, hci_status);
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+	/* check the state after obtaing the lock to protect the HCI_UP
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+	 * against any races from hci_dev_do_close when the controller
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+	 * gets removed.
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+	 */
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+	if (test_bit(HCI_UP, &hdev->flags))
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+		ret = __hci_req_sync(hdev, req, opt, timeout, hci_status);
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+	else
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+		ret = -ENETDOWN;
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 	hci_req_sync_unlock(hdev);
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 	return ret;
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-- 
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2.26.3
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