UBUNTU-CVE-2023-52572: Use After Free
In the Linux kernel, the following vulnerability has been resolved: cifs: Fix UAF in cifsdemultiplexthread() There is a UAF when xfstests on cifs: BUG: KASAN: use-after-free in smb2isnetworknamedeleted+0x27/0x160 Read of size 4 at addr ffff88810103fc08 by task cifsd/923 CPU: 1 PID: 923 Comm: cifsd Not tainted 6.1.0-rc4+ #45 ... Call Trace: <TASK> dumpstacklvl+0x34/0x44 printreport+0x171/0x472 kasanreport+0xad/0x130 kasancheckrange+0x145/0x1a0 smb2isnetworknamedeleted+0x27/0x160 cifsdemultiplexthread.cold+0x172/0x5a4 kthread+0x165/0x1a0 retfromfork+0x1f/0x30 </TASK> Allocated by task 923: kasansavestack+0x1e/0x40 kasansettrack+0x21/0x30 kasanslaballoc+0x54/0x60 kmemcachealloc+0x147/0x320 mempoolalloc+0xe1/0x260 cifssmallbufget+0x24/0x60 allocatebuffers+0xa1/0x1c0 cifsdemultiplexthread+0x199/0x10d0 kthread+0x165/0x1a0 retfromfork+0x1f/0x30 Freed by task 921: kasansavestack+0x1e/0x40 kasansettrack+0x21/0x30 kasansavefreeinfo+0x2a/0x40 kasanslabfree+0x143/0x1b0 kmemcachefree+0xe3/0x4d0 cifssmallbufrelease+0x29/0x90 SMB2negotiate+0x8b7/0x1c60 smb2negotiate+0x51/0x70 cifsnegotiateprotocol+0xf0/0x160 cifsgetsmbses+0x5fa/0x13c0 mountgetconns+0x7a/0x750 cifsmount+0x103/0xd00 cifssmb3domount+0x1dd/0xcb0 smb3gettree+0x1d5/0x300 vfsgettree+0x41/0xf0 pathmount+0x9b3/0xdd0 x64sysmount+0x190/0x1d0 dosyscall64+0x35/0x80 entrySYSCALL64afterhwframe+0x46/0xb0 The UAF is because: mount(pid: 921) | cifsd(pid: 923) -------------------------------|------------------------------- | cifsdemultiplexthread SMB2negotiate | cifssendrecv | compoundsendrecv | smbsendrqst | waitforresponse | waiteventstate [1] | | standardreceive3 | cifshandlestandard | handlemid | mid->respbuf = buf; [2] | dequeuemid [3] KILL the process [4] | respiov[i].iovbase = buf | freerspbuf [5] | | isnetworknamedeleted [6] | callback 1. After send request to server, wait the response until mid->midstate != SUBMITTED; 2. Receive response from server, and set it to mid; 3. Set the mid state to RECEIVED; 4. Kill the process, the mid state already RECEIVED, get 0; 5. Handle and release the negotiate response; 6. UAF. It can be easily reproduce with add some delay in [3] - [6]. Only sync call has the problem since async call's callback is executed in cifsd process. Add an extra state to mark the mid state to READY before wakeup the waitter, then it can get the resp safely.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
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ubuntu/linux-azure-5.15to a version that resolves this vulnerability.Fixed in 5.15.0-1078.87~20.04.1 - Upgrade
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ubuntu/linux-aws-5.15to a version that resolves this vulnerability.Fixed in 5.15.0-1088.95~20.04.1 - Upgrade
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ubuntu/linux-gcp-5.15to a version that resolves this vulnerability.Fixed in 5.15.0-1087.96~20.04.2 - Upgrade
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ubuntu/linux-hwe-5.15to a version that resolves this vulnerability.Fixed in 5.15.0-144.157~20.04.1 - Upgrade
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ubuntu/linux-ibm-5.15to a version that resolves this vulnerability.Fixed in 5.15.0-1080.83~20.04.1 - Upgrade
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ubuntu/linux-intel-iotg-5.15to a version that resolves this vulnerability.Fixed in 5.15.0-1083.89~20.04.1 - Upgrade
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ubuntu/linux-lowlatency-hwe-5.15to a version that resolves this vulnerability.Fixed in 5.15.0-144.157~20.04.1 - Upgrade
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ubuntu/linux-nvidia-tegra-5.15to a version that resolves this vulnerability.Fixed in 5.15.0-1041.41~20.04.1 - Upgrade
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ubuntu/linux-oracle-5.15to a version that resolves this vulnerability.Fixed in 5.15.0-1085.91~20.04.3 - Upgrade
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ubuntu/linux-riscv-5.15to a version that resolves this vulnerability.Fixed in 5.15.0-1083.87~20.04.1 - Upgrade
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ubuntu/linuxto a version that resolves this vulnerability.Fixed in 5.15.0-144.157 - Upgrade
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ubuntu/linux-awsto a version that resolves this vulnerability.Fixed in 5.15.0-1088.95 - Upgrade
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ubuntu/linux-azureto a version that resolves this vulnerability.Fixed in 5.15.0-1075.84 - Upgrade
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ubuntu/linux-azure-fdeto a version that resolves this vulnerability.Fixed in 5.15.0-1076.85.1 - Upgrade
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ubuntu/linux-gcpto a version that resolves this vulnerability.Fixed in 5.15.0-1087.96 - Upgrade
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ubuntu/linux-gketo a version that resolves this vulnerability.Fixed in 5.15.0-1085.91 - Upgrade
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ubuntu/linux-gkeopto a version that resolves this vulnerability.Fixed in 5.15.0-1070.78 - Upgrade
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ubuntu/linux-ibmto a version that resolves this vulnerability.Fixed in 5.15.0-1080.83 - Upgrade
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ubuntu/linux-intel-iotgto a version that resolves this vulnerability.Fixed in 5.15.0-1083.89 - Upgrade
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ubuntu/linux-kvmto a version that resolves this vulnerability.Fixed in 5.15.0-1084.89 - Upgrade
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ubuntu/linux-lowlatencyto a version that resolves this vulnerability.Fixed in 5.15.0-144.157 - Upgrade
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ubuntu/linux-nvidiato a version that resolves this vulnerability.Fixed in 5.15.0-1082.83 - Upgrade
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ubuntu/linux-nvidia-6.5to a version that resolves this vulnerability.Fixed in 6.5.0-1014.14 - Upgrade
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ubuntu/linux-nvidia-tegrato a version that resolves this vulnerability.Fixed in 5.15.0-1041.41 - Upgrade
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ubuntu/linux-nvidia-tegra-igxto a version that resolves this vulnerability.Fixed in 5.15.0-1030.30 - Upgrade
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ubuntu/linux-oracleto a version that resolves this vulnerability.Fixed in 5.15.0-1085.91 - Upgrade
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ubuntu/linux-raspito a version that resolves this vulnerability.Fixed in 5.15.0-1083.86 - Upgrade
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ubuntu/linux-xilinx-zynqmpto a version that resolves this vulnerability.Fixed in 5.15.0-1052.56 - Upgrade
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ubuntu/linux-bluefieldto a version that resolves this vulnerability.Fixed in 5.15.0-1072.74 - Upgrade
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ubuntu/linux-intel-iot-realtimeto a version that resolves this vulnerability.Fixed in 5.15.0-1081.83 - Upgrade
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ubuntu/linux-realtimeto a version that resolves this vulnerability.Fixed in 5.15.0-1088.97 - Upgrade
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ubuntu/linux-aws-fipsto a version that resolves this vulnerability.Fixed in 5.15.0-1088.95+fips1 - Upgrade
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ubuntu/linux-azure-fipsto a version that resolves this vulnerability.Fixed in 5.15.0-1075.84+fips1 - Upgrade
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ubuntu/linux-fipsto a version that resolves this vulnerability.Fixed in 5.15.0-144.157+fips1 - Upgrade
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ubuntu/linux-gcp-fipsto a version that resolves this vulnerability.Fixed in 5.15.0-1087.96+fips1 - Compensating control
Fix the CIFS synchronous response handling to prevent the use-after-free: add a READY mid state, set the mid state to READY before waking the waiter, wait for the response while mid->mid_state != SUBMITTED, and safely handle and release the negotiate response.
Event History
Frequently Asked Questions
Which Ubuntu kernel package families are listed as affected?
The listed software includes ubuntu/linux, ubuntu/linux-fips, ubuntu/linux-aws, ubuntu/linux-aws-fips, ubuntu/linux-azure, ubuntu/linux-azure-fips, ubuntu/linux-gcp, and ubuntu/linux-gcp-fips.
Which kernel functionality is involved?
The issue is in the CIFS client path, specifically the cifs_demultiplex_thread() processing path during SMB negotiation. The reported use-after-free occurs in smb2_is_network_name_deleted().
What security impact is indicated by the supplied severity data?
The supplied vector indicates local access, low privileges, low attack complexity, and no user interaction. It indicates high availability impact, with no indicated impact to confidentiality or integrity.