UBUNTU-CVE-2024-50121: Use After Free

Q: Which systems are exposed to this issue?

The issue applies to the listed Ubuntu kernel packages: linux-realtime, linux-azure, linux-gcp, linux-gke, linux-gkeop, linux-riscv, linux-hwe-edge, and linux-azure-fde. The vulnerable path involves the kernel NFS server (nfsd) and its NFSv4 client-state shutdown handling.

Q: What access does an attacker need?

The supplied CVSS vector indicates local access and low privileges are required, with no user interaction required. The affected condition occurs during nfsd shutdown while the nfsd client shrinker is concurrently running.

Q: What activity triggers the problematic race?

The described normal shutdown action is setting the nfsd thread count to zero with echo 0 > /proc/fs/nfsd/threads. If this occurs while nfsd_client_shrinker is expiring a client, resource teardown can race with client destruction and cause use-after-free conditions.

Published Nov 5, 2024

Updated

In the Linux kernel, the following vulnerability has been resolved: nfsd: cancel nfsdshrinkerwork using sync mode in nfs4stateshutdownnet In the normal case, when we excute echo 0 > /proc/fs/nfsd/threads, the function nfs4statedestroynet in nfs4stateshutdownnet will release all resources related to the hashed nfs4client. If the nfsdclientshrinker is running concurrently, the expireclient function will first unhash this client and then destroy it. This can lead to the following warning. Additionally, numerous use-after-free errors may occur as well. nfsdclientshrinker echo 0 > /proc/fs/nfsd/threads expireclient nfsdshutdownnet unhashclient ... nfs4stateshutdownnet / won't wait shrinker exit / / cancelwork(&nn->nfsdshrinkerwork) nfsdfile for this / won't destroy unhashed client1 / client1 still alive nfs4statedestroynet / nfsdfilecacheshutdown / trigger warning / kmemcachedestroy(nfsdfileslab) kmemcachedestroy(nfsdfilemarkslab) / release nfsdfile and mark / destroyclient ==================================================================== BUG nfsdfile (Not tainted): Objects remaining in nfsdfile on kmemcacheshutdown() -------------------------------------------------------------------- CPU: 4 UID: 0 PID: 764 Comm: sh Not tainted 6.12.0-rc3+ #1 dumpstacklvl+0x53/0x70 slaberr+0xb0/0xf0 kmemcacheshutdown+0x15c/0x310 kmemcachedestroy+0x66/0x160 nfsdfilecacheshutdown+0xac/0x210 [nfsd] nfsddestroyserv+0x251/0x2a0 [nfsd] nfsdsvc+0x125/0x1e0 [nfsd] writethreads+0x16a/0x2a0 [nfsd] nfsctltransactionwrite+0x74/0xa0 [nfsd] vfswrite+0x1a5/0x6d0 ksyswrite+0xc1/0x160 dosyscall64+0x5f/0x170 entrySYSCALL64afterhwframe+0x76/0x7e ==================================================================== BUG nfsdfilemark (Tainted: G B W ): Objects remaining nfsdfilemark on kmemcacheshutdown() -------------------------------------------------------------------- dumpstacklvl+0x53/0x70 slaberr+0xb0/0xf0 kmemcacheshutdown+0x15c/0x310 kmemcachedestroy+0x66/0x160 nfsdfilecacheshutdown+0xc8/0x210 [nfsd] nfsddestroyserv+0x251/0x2a0 [nfsd] nfsdsvc+0x125/0x1e0 [nfsd] writethreads+0x16a/0x2a0 [nfsd] nfsctltransactionwrite+0x74/0xa0 [nfsd] vfswrite+0x1a5/0x6d0 ksyswrite+0xc1/0x160 dosyscall64+0x5f/0x170 entrySYSCALL64afterhwframe+0x76/0x7e To resolve this issue, cancel nfsdshrinkerwork using synchronous mode in nfs4stateshutdownnet.

Affected Software

146 affected componentsFixes available

ubuntu/linux-hwe-edge*

ubuntu/linux-aws-5.0*

ubuntu/linux-aws-5.3*

ubuntu/linux-azure*

ubuntu/linux-azure-5.3*

ubuntu/linux-azure-edge*

ubuntu/linux-gcp*

ubuntu/linux-gcp-5.3*

ubuntu/linux-gke-4.15*

ubuntu/linux-gke-5.4*

ubuntu/linux-gkeop-5.4*

ubuntu/linux-hwe*

ubuntu/linux-hwe-edge*

ubuntu/linux-oem*

ubuntu/linux-oracle-5.0*

ubuntu/linux-oracle-5.3*

ubuntu/linux-aws-5.15<5.15.0-1080.87~20.04.1

5.15.0-1080.87~20.04.1

ubuntu/linux-azure-5.15<5.15.0-1086.95~20.04.1

5.15.0-1086.95~20.04.1

ubuntu/linux-gcp-5.15<5.15.0-1081.90~20.04.1

5.15.0-1081.90~20.04.1

ubuntu/linux-hwe-5.15<5.15.0-136.147~20.04.1

5.15.0-136.147~20.04.1

ubuntu/linux-ibm-5.15<5.15.0-1074.77~20.04.1

5.15.0-1074.77~20.04.1

ubuntu/linux-intel-iotg-5.15<5.15.0-1077.83~20.04.1

5.15.0-1077.83~20.04.1

ubuntu/linux-lowlatency-hwe-5.15<5.15.0-135.146~20.04.1

5.15.0-135.146~20.04.1

ubuntu/linux-oracle-5.15<5.15.0-1077.83~20.04.1

5.15.0-1077.83~20.04.1

ubuntu/linux-riscv-5.15<5.15.0-1075.79~20.04.1

5.15.0-1075.79~20.04.1

ubuntu/linux-aws-5.11*

ubuntu/linux-aws-5.13*

ubuntu/linux-aws-5.8*

ubuntu/linux-azure-5.11*

ubuntu/linux-azure-5.13*

ubuntu/linux-azure-5.8*

ubuntu/linux-azure-fde*

ubuntu/linux-gcp-5.11*

ubuntu/linux-gcp-5.13*

ubuntu/linux-gcp-5.8*

ubuntu/linux-gke*

ubuntu/linux-gke-5.15*

ubuntu/linux-gkeop*

ubuntu/linux-gkeop-5.15*

ubuntu/linux-hwe-5.11*

ubuntu/linux-hwe-5.13*

ubuntu/linux-hwe-5.8*

ubuntu/linux-intel-5.13*

ubuntu/linux-nvidia-tegra-5.15<5.15.0-1039.39~20.04.1

5.15.0-1039.39~20.04.1

ubuntu/linux-oem-5.10*

ubuntu/linux-oem-5.13*

ubuntu/linux-oem-5.6*

ubuntu/linux-oracle-5.11*

ubuntu/linux-oracle-5.13*

ubuntu/linux-oracle-5.8*

ubuntu/linux-raspi2*

ubuntu/linux-riscv*

ubuntu/linux-riscv-5.11*

ubuntu/linux-riscv-5.8*

ubuntu/linux<5.15.0-135.146

5.15.0-135.146

ubuntu/linux-allwinner-5.19*

ubuntu/linux-aws<5.15.0-1080.87

5.15.0-1080.87

ubuntu/linux-aws-5.19*

ubuntu/linux-aws-6.2*

ubuntu/linux-aws-6.5*

ubuntu/linux-aws-6.8<6.8.0-1027.29~22.04.1

6.8.0-1027.29~22.04.1

ubuntu/linux-azure<5.15.0-1084.93

5.15.0-1084.93

ubuntu/linux-azure-5.19*

ubuntu/linux-azure-6.2*

ubuntu/linux-azure-6.5*

ubuntu/linux-azure-6.8<6.8.0-1027.32~22.04.1

6.8.0-1027.32~22.04.1

ubuntu/linux-azure-fde<5.15.0-1084.93.1

5.15.0-1084.93.1

ubuntu/linux-azure-fde-5.19*

ubuntu/linux-azure-fde-6.2*

ubuntu/linux-gcp<5.15.0-1079.88

5.15.0-1079.88

ubuntu/linux-gcp-5.19*

ubuntu/linux-gcp-6.2*

ubuntu/linux-gcp-6.5*

ubuntu/linux-gcp-6.8<6.8.0-1028.30~22.04.1

6.8.0-1028.30~22.04.1

ubuntu/linux-gke<5.15.0-1077.83

5.15.0-1077.83

ubuntu/linux-gkeop<5.15.0-1062.70

5.15.0-1062.70

ubuntu/linux-hwe-5.19*

ubuntu/linux-hwe-6.2*

ubuntu/linux-hwe-6.5*

ubuntu/linux-hwe-6.8<6.8.0-58.60~22.04.1

6.8.0-58.60~22.04.1

ubuntu/linux-ibm<5.15.0-1072.75

5.15.0-1072.75

ubuntu/linux-ibm-6.8<6.8.0-1024.24~22.04.1

6.8.0-1024.24~22.04.1

ubuntu/linux-intel-iot-realtime<5.15.0-1073.75

5.15.0-1073.75

ubuntu/linux-intel-iotg<5.15.0-1075.81

5.15.0-1075.81

ubuntu/linux-kvm<5.15.0-1076.81

5.15.0-1076.81

ubuntu/linux-lowlatency<5.15.0-135.146

5.15.0-135.146

ubuntu/linux-lowlatency-hwe-5.19*

ubuntu/linux-lowlatency-hwe-6.2*

ubuntu/linux-lowlatency-hwe-6.5*

ubuntu/linux-lowlatency-hwe-6.8<6.8.0-58.60.1~22.04.1

6.8.0-58.60.1~22.04.1

ubuntu/linux-nvidia<5.15.0-1074.75

5.15.0-1074.75

ubuntu/linux-nvidia-6.2*

ubuntu/linux-nvidia-6.5*

ubuntu/linux-nvidia-6.8<6.8.0-1026.29~22.04.1

6.8.0-1026.29~22.04.1

ubuntu/linux-nvidia-tegra<5.15.0-1033.33

5.15.0-1033.33

ubuntu/linux-nvidia-tegra-igx<5.15.0-1021.21

5.15.0-1021.21

ubuntu/linux-oem-5.17*

ubuntu/linux-oem-6.0*

ubuntu/linux-oem-6.1*

ubuntu/linux-oem-6.5*

ubuntu/linux-oracle<5.15.0-1077.83

5.15.0-1077.83

ubuntu/linux-oracle-6.5*

ubuntu/linux-oracle-6.8<6.8.0-1024.25~22.04.1

6.8.0-1024.25~22.04.1

ubuntu/linux-raspi<5.15.0-1074.77

5.15.0-1074.77

ubuntu/linux-realtime*

ubuntu/linux-riscv*

ubuntu/linux-riscv-5.19*

ubuntu/linux-riscv-6.5*

ubuntu/linux-riscv-6.8<6.8.0-58.60.1~22.04.1

6.8.0-58.60.1~22.04.1

ubuntu/linux-starfive-5.19*

ubuntu/linux-starfive-6.2*

ubuntu/linux-starfive-6.5*

ubuntu/linux-xilinx-zynqmp<5.15.0-1044.48

5.15.0-1044.48

ubuntu/linux-bluefield<5.15.0-1062.64

5.15.0-1062.64

ubuntu/linux-realtime<5.15.0-1080.88

5.15.0-1080.88

ubuntu/linux-realtime-6.8<6.8.1-1020.21~22.04.1

6.8.1-1020.21~22.04.1

ubuntu/linux-aws-fips<5.15.0-1080.87+fips1

5.15.0-1080.87+fips1

ubuntu/linux-azure-fips<5.15.0-1083.92+fips1

5.15.0-1083.92+fips1

ubuntu/linux-fips<5.15.0-135.146+fips1

5.15.0-135.146+fips1

ubuntu/linux-gcp-fips<5.15.0-1079.88+fips1

5.15.0-1079.88+fips1

ubuntu/linux<6.8.0-58.60

6.8.0-58.60

ubuntu/linux-aws<6.8.0-1027.29

6.8.0-1027.29

ubuntu/linux-azure<6.8.0-1027.32

6.8.0-1027.32

ubuntu/linux-azure-6.11<6.11.0-1012.12~24.04.1

6.11.0-1012.12~24.04.1

ubuntu/linux-azure-nvidia<6.8.0-1014.15

6.8.0-1014.15

ubuntu/linux-gcp<6.8.0-1028.30

6.8.0-1028.30

ubuntu/linux-gcp-6.11<6.11.0-1011.11~24.04.1

6.11.0-1011.11~24.04.1

ubuntu/linux-gke<6.8.0-1023.27

6.8.0-1023.27

ubuntu/linux-gkeop<6.8.0-1010.12

6.8.0-1010.12

ubuntu/linux-ibm<6.8.0-1024.24

6.8.0-1024.24

ubuntu/linux-lowlatency<6.8.0-58.60.1

6.8.0-58.60.1

ubuntu/linux-nvidia<6.8.0-1026.29

6.8.0-1026.29

ubuntu/linux-nvidia-6.11<6.11.0-1007.7

6.11.0-1007.7

ubuntu/linux-nvidia-lowlatency<6.8.0-1026.29.1

6.8.0-1026.29.1

ubuntu/linux-nvidia-tegra<6.8.0-1008.8

6.8.0-1008.8

ubuntu/linux-oem-6.11<6.11.0-1015.15

6.11.0-1015.15

ubuntu/linux-oem-6.8<6.8.0-1026.26

6.8.0-1026.26

ubuntu/linux-oracle<6.8.0-1024.25

6.8.0-1024.25

ubuntu/linux-raspi<6.8.0-1028.32

6.8.0-1028.32

ubuntu/linux-raspi-realtime*

ubuntu/linux-realtime*

ubuntu/linux-riscv<6.8.0-58.60.1

6.8.0-58.60.1

ubuntu/linux-xilinx<6.8.0-1017.18

6.8.0-1017.18

ubuntu/linux-raspi-realtime<6.8.0-2023.24

6.8.0-2023.24

ubuntu/linux-realtime<6.8.1-1020.21

6.8.1-1020.21

ubuntu/linux-fips<6.8.0-78.78+fips1

6.8.0-78.78+fips1

Remediation

Recommended actions to resolve this vulnerability, in priority order.

Upgrade
Upgrade ubuntu/linux-aws-5.15 to a version that resolves this vulnerability.
Fixed in 5.15.0-1080.87~20.04.1
Upgrade
Upgrade ubuntu/linux-azure-5.15 to a version that resolves this vulnerability.
Fixed in 5.15.0-1086.95~20.04.1
Upgrade
Upgrade ubuntu/linux-gcp-5.15 to a version that resolves this vulnerability.
Fixed in 5.15.0-1081.90~20.04.1
Upgrade
Upgrade ubuntu/linux-hwe-5.15 to a version that resolves this vulnerability.
Fixed in 5.15.0-136.147~20.04.1
Upgrade
Upgrade ubuntu/linux-ibm-5.15 to a version that resolves this vulnerability.
Fixed in 5.15.0-1074.77~20.04.1
Upgrade
Upgrade ubuntu/linux-intel-iotg-5.15 to a version that resolves this vulnerability.
Fixed in 5.15.0-1077.83~20.04.1
Upgrade
Upgrade ubuntu/linux-lowlatency-hwe-5.15 to a version that resolves this vulnerability.
Fixed in 5.15.0-135.146~20.04.1
Upgrade
Upgrade ubuntu/linux-oracle-5.15 to a version that resolves this vulnerability.
Fixed in 5.15.0-1077.83~20.04.1
Upgrade
Upgrade ubuntu/linux-riscv-5.15 to a version that resolves this vulnerability.
Fixed in 5.15.0-1075.79~20.04.1
Upgrade
Upgrade ubuntu/linux-nvidia-tegra-5.15 to a version that resolves this vulnerability.
Fixed in 5.15.0-1039.39~20.04.1
Upgrade
Upgrade ubuntu/linux to a version that resolves this vulnerability.
Fixed in 5.15.0-135.146
Upgrade
Upgrade ubuntu/linux-aws to a version that resolves this vulnerability.
Fixed in 5.15.0-1080.87
Upgrade
Upgrade ubuntu/linux-aws-6.8 to a version that resolves this vulnerability.
Fixed in 6.8.0-1027.29~22.04.1
Upgrade
Upgrade ubuntu/linux-azure to a version that resolves this vulnerability.
Fixed in 5.15.0-1084.93
Upgrade
Upgrade ubuntu/linux-azure-6.8 to a version that resolves this vulnerability.
Fixed in 6.8.0-1027.32~22.04.1
Upgrade
Upgrade ubuntu/linux-azure-fde to a version that resolves this vulnerability.
Fixed in 5.15.0-1084.93.1
Upgrade
Upgrade ubuntu/linux-gcp to a version that resolves this vulnerability.
Fixed in 5.15.0-1079.88
Upgrade
Upgrade ubuntu/linux-gcp-6.8 to a version that resolves this vulnerability.
Fixed in 6.8.0-1028.30~22.04.1
Upgrade
Upgrade ubuntu/linux-gke to a version that resolves this vulnerability.
Fixed in 5.15.0-1077.83
Upgrade
Upgrade ubuntu/linux-gkeop to a version that resolves this vulnerability.
Fixed in 5.15.0-1062.70
Upgrade
Upgrade ubuntu/linux-hwe-6.8 to a version that resolves this vulnerability.
Fixed in 6.8.0-58.60~22.04.1
Upgrade
Upgrade ubuntu/linux-ibm to a version that resolves this vulnerability.
Fixed in 5.15.0-1072.75
Upgrade
Upgrade ubuntu/linux-ibm-6.8 to a version that resolves this vulnerability.
Fixed in 6.8.0-1024.24~22.04.1
Upgrade
Upgrade ubuntu/linux-intel-iot-realtime to a version that resolves this vulnerability.
Fixed in 5.15.0-1073.75
Upgrade
Upgrade ubuntu/linux-intel-iotg to a version that resolves this vulnerability.
Fixed in 5.15.0-1075.81
Upgrade
Upgrade ubuntu/linux-kvm to a version that resolves this vulnerability.
Fixed in 5.15.0-1076.81
Upgrade
Upgrade ubuntu/linux-lowlatency to a version that resolves this vulnerability.
Fixed in 5.15.0-135.146
Upgrade
Upgrade ubuntu/linux-lowlatency-hwe-6.8 to a version that resolves this vulnerability.
Fixed in 6.8.0-58.60.1~22.04.1
Upgrade
Upgrade ubuntu/linux-nvidia to a version that resolves this vulnerability.
Fixed in 5.15.0-1074.75
Upgrade
Upgrade ubuntu/linux-nvidia-6.8 to a version that resolves this vulnerability.
Fixed in 6.8.0-1026.29~22.04.1
Upgrade
Upgrade ubuntu/linux-nvidia-tegra to a version that resolves this vulnerability.
Fixed in 5.15.0-1033.33
Upgrade
Upgrade ubuntu/linux-nvidia-tegra-igx to a version that resolves this vulnerability.
Fixed in 5.15.0-1021.21
Upgrade
Upgrade ubuntu/linux-oracle to a version that resolves this vulnerability.
Fixed in 5.15.0-1077.83
Upgrade
Upgrade ubuntu/linux-oracle-6.8 to a version that resolves this vulnerability.
Fixed in 6.8.0-1024.25~22.04.1
Upgrade
Upgrade ubuntu/linux-raspi to a version that resolves this vulnerability.
Fixed in 5.15.0-1074.77
Upgrade
Upgrade ubuntu/linux-riscv-6.8 to a version that resolves this vulnerability.
Fixed in 6.8.0-58.60.1~22.04.1
Upgrade
Upgrade ubuntu/linux-xilinx-zynqmp to a version that resolves this vulnerability.
Fixed in 5.15.0-1044.48
Upgrade
Upgrade ubuntu/linux-bluefield to a version that resolves this vulnerability.
Fixed in 5.15.0-1062.64
Upgrade
Upgrade ubuntu/linux-realtime to a version that resolves this vulnerability.
Fixed in 5.15.0-1080.88
Upgrade
Upgrade ubuntu/linux-realtime-6.8 to a version that resolves this vulnerability.
Fixed in 6.8.1-1020.21~22.04.1
Upgrade
Upgrade ubuntu/linux-aws-fips to a version that resolves this vulnerability.
Fixed in 5.15.0-1080.87+fips1
Upgrade
Upgrade ubuntu/linux-azure-fips to a version that resolves this vulnerability.
Fixed in 5.15.0-1083.92+fips1
Upgrade
Upgrade ubuntu/linux-fips to a version that resolves this vulnerability.
Fixed in 5.15.0-135.146+fips1
Upgrade
Upgrade ubuntu/linux-gcp-fips to a version that resolves this vulnerability.
Fixed in 5.15.0-1079.88+fips1
Upgrade
Upgrade ubuntu/linux to a version that resolves this vulnerability.
Fixed in 6.8.0-58.60
Upgrade
Upgrade ubuntu/linux-aws to a version that resolves this vulnerability.
Fixed in 6.8.0-1027.29
Upgrade
Upgrade ubuntu/linux-azure to a version that resolves this vulnerability.
Fixed in 6.8.0-1027.32
Upgrade
Upgrade ubuntu/linux-azure-6.11 to a version that resolves this vulnerability.
Fixed in 6.11.0-1012.12~24.04.1
Upgrade
Upgrade ubuntu/linux-azure-nvidia to a version that resolves this vulnerability.
Fixed in 6.8.0-1014.15
Upgrade
Upgrade ubuntu/linux-gcp to a version that resolves this vulnerability.
Fixed in 6.8.0-1028.30
Upgrade
Upgrade ubuntu/linux-gcp-6.11 to a version that resolves this vulnerability.
Fixed in 6.11.0-1011.11~24.04.1
Upgrade
Upgrade ubuntu/linux-gke to a version that resolves this vulnerability.
Fixed in 6.8.0-1023.27
Upgrade
Upgrade ubuntu/linux-gkeop to a version that resolves this vulnerability.
Fixed in 6.8.0-1010.12
Upgrade
Upgrade ubuntu/linux-ibm to a version that resolves this vulnerability.
Fixed in 6.8.0-1024.24
Upgrade
Upgrade ubuntu/linux-lowlatency to a version that resolves this vulnerability.
Fixed in 6.8.0-58.60.1
Upgrade
Upgrade ubuntu/linux-nvidia to a version that resolves this vulnerability.
Fixed in 6.8.0-1026.29
Upgrade
Upgrade ubuntu/linux-nvidia-6.11 to a version that resolves this vulnerability.
Fixed in 6.11.0-1007.7
Upgrade
Upgrade ubuntu/linux-nvidia-lowlatency to a version that resolves this vulnerability.
Fixed in 6.8.0-1026.29.1
Upgrade
Upgrade ubuntu/linux-nvidia-tegra to a version that resolves this vulnerability.
Fixed in 6.8.0-1008.8
Upgrade
Upgrade ubuntu/linux-oem-6.11 to a version that resolves this vulnerability.
Fixed in 6.11.0-1015.15
Upgrade
Upgrade ubuntu/linux-oem-6.8 to a version that resolves this vulnerability.
Fixed in 6.8.0-1026.26
Upgrade
Upgrade ubuntu/linux-oracle to a version that resolves this vulnerability.
Fixed in 6.8.0-1024.25
Upgrade
Upgrade ubuntu/linux-raspi to a version that resolves this vulnerability.
Fixed in 6.8.0-1028.32
Upgrade
Upgrade ubuntu/linux-riscv to a version that resolves this vulnerability.
Fixed in 6.8.0-58.60.1
Upgrade
Upgrade ubuntu/linux-xilinx to a version that resolves this vulnerability.
Fixed in 6.8.0-1017.18
Upgrade
Upgrade ubuntu/linux-raspi-realtime to a version that resolves this vulnerability.
Fixed in 6.8.0-2023.24
Upgrade
Upgrade ubuntu/linux-realtime to a version that resolves this vulnerability.
Fixed in 6.8.1-1020.21
Upgrade
Upgrade ubuntu/linux-fips to a version that resolves this vulnerability.
Fixed in 6.8.0-78.78+fips1
Configuration
Cancel nfsd_shrinker_work using synchronous mode in nfs4_state_shutdown_net so shrinker work has exited before nfs4 state and nfsd file caches are destroyed.
Linux kernel nfsd nfsd_shrinker_work cancellation in nfs4_state_shutdown_net = synchronous mode

Event History

Nov 5, 2024

CVE Published

via OSV·06:15 PM

Data Sourced

via OSV·06:15 PM

DescriptionSeverityAffected Software

Frequently Asked Questions

Which systems are exposed to this issue?

The issue applies to the listed Ubuntu kernel packages: linux-realtime, linux-azure, linux-gcp, linux-gke, linux-gkeop, linux-riscv, linux-hwe-edge, and linux-azure-fde. The vulnerable path involves the kernel NFS server (nfsd) and its NFSv4 client-state shutdown handling.

What access does an attacker need?

The supplied CVSS vector indicates local access and low privileges are required, with no user interaction required. The affected condition occurs during nfsd shutdown while the nfsd client shrinker is concurrently running.

What activity triggers the problematic race?

The described normal shutdown action is setting the nfsd thread count to zero with echo 0 > /proc/fs/nfsd/threads. If this occurs while nfsd_client_shrinker is expiring a client, resource teardown can race with client destruction and cause use-after-free conditions.

How might an affected system present?

The described symptoms include a kernel BUG warning about objects remaining in the nfsd_file cache during cache destruction, as well as possible use-after-free errors. These symptoms would be expected around nfsd shutdown and concurrent client-expiration activity.

UBUNTU-CVE-2024-50121: Use After Free

Affected Software

Remediation

Event History

Frequently Asked Questions

Which systems are exposed to this issue?

What access does an attacker need?

What activity triggers the problematic race?

How might an affected system present?

Company

Resources

Contact

Frequently Asked Questions

Which systems are exposed to this issue?

What access does an attacker need?

What activity triggers the problematic race?

How might an affected system present?