Blame SOURCES/CVE-2021-32399.patch

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From: Artem Savkov <asavkov@redhat.com>
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Subject: [RHEL-7.9 CVE-2021-32399 KPATCH] bluetooth: eliminate the potential race condition when removing the HCI controller
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Date: Wed,  7 Jul 2021 17:13:32 +0200
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Kernels:
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3.10.0-1160.el7
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3.10.0-1160.2.1.el7
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3.10.0-1160.2.2.el7
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3.10.0-1160.6.1.el7
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3.10.0-1160.11.1.el7
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3.10.0-1160.15.2.el7
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3.10.0-1160.21.1.el7
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3.10.0-1160.24.1.el7
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3.10.0-1160.25.1.el7
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3.10.0-1160.31.1.el7
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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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3.10.0-1160.el7
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3.10.0-1160.2.1.el7
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3.10.0-1160.2.2.el7
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3.10.0-1160.6.1.el7
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3.10.0-1160.11.1.el7
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3.10.0-1160.15.2.el7
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3.10.0-1160.21.1.el7
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3.10.0-1160.24.1.el7
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3.10.0-1160.25.1.el7
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3.10.0-1160.31.1.el7
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3.10.0-1160.36.2.el7
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Modifications: none
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Z-MR: https://gitlab.com/redhat/rhel/src/kernel/rhel-7/-/merge_requests/171
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commit 168b363c94eac82c2e3531bd2ae9dfa2f369d4be
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Author: Gopal Tiwari <gtiwari@redhat.com>
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Date:   Mon Jun 14 13:04:00 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/show_bug.cgi?id=1971457
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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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    Signed-off-by: Gopal Tiwari <gtiwari@redhat.com>
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Signed-off-by: Artem Savkov <asavkov@redhat.com>
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Acked-by: Joe Lawrence <joe.lawrence@redhat.com>
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Acked-by: Yannick Cote <ycote@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 1015d9c8d97dd..9e25e77042503 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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@@ -275,12 +275,16 @@ 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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