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scsi: mptsas: dequeue request object in case of an error

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Fix CVE-2021-3392

While processing SCSI i/o requests in mptsas_process_scsi_io_request(),
the Megaraid emulator appends new MPTSASRequest object 'req' to
the 's->pending' queue. In case of an error, this same object gets
dequeued in mptsas_free_request() only if SCSIRequest object
'req->sreq' is initialised. This may lead to a use-after-free issue.
Unconditionally dequeue 'req' object from 's->pending' to avoid it.

Fixes: CVE-2021-3392
Buglink: https://bugs.launchpad.net/qemu/+bug/1914236
Reported-by: Cheolwoo Myung <cwmyung@snu.ac.kr>
Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>

Signed-off-by: Jiajie Li <lijiajie11@huawei.com>
This commit is contained in:
Chen Qun 2021-05-17 14:24:49 +08:00
parent da8ce906cb
commit 88ca69705a
1 changed files with 41 additions and 0 deletions
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41
scsi-mptsas-dequeue-request-object-in-case-of-an-err.patch Normal file
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@ -0,0 +1,41 @@
From 27b68c47d739a3c4e5ece95ab002ee852103e11f Mon Sep 17 00:00:00 2001
From: Prasad J Pandit <pjp@fedoraproject.org>
Date: Mon, 17 May 2021 14:24:49 +0800
Subject: [PATCH] scsi: mptsas: dequeue request object in case of an error
Fix CVE-2021-3392
While processing SCSI i/o requests in mptsas_process_scsi_io_request(),
the Megaraid emulator appends new MPTSASRequest object 'req' to
the 's->pending' queue. In case of an error, this same object gets
dequeued in mptsas_free_request() only if SCSIRequest object
'req->sreq' is initialised. This may lead to a use-after-free issue.
Unconditionally dequeue 'req' object from 's->pending' to avoid it.
Fixes: CVE-2021-3392
Buglink: https://bugs.launchpad.net/qemu/+bug/1914236
Reported-by: Cheolwoo Myung <cwmyung@snu.ac.kr>
Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
Signed-off-by: Jiajie Li <lijiajie11@huawei.com>
---
hw/scsi/mptsas.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/hw/scsi/mptsas.c b/hw/scsi/mptsas.c
index 3f94d5ab55..4d23f045d7 100644
--- a/hw/scsi/mptsas.c
+++ b/hw/scsi/mptsas.c
@@ -259,8 +259,8 @@ static void mptsas_free_request(MPTSASRequest *req)
req->sreq->hba_private = NULL;
scsi_req_unref(req->sreq);
req->sreq = NULL;
- QTAILQ_REMOVE(&s->pending, req, next);
}
+ QTAILQ_REMOVE(&s->pending, req, next);
qemu_sglist_destroy(&req->qsg);
g_free(req);
}
--
2.27.0