UBUNTU-CVE-2024-47699: Null Pointer Dereference
In the Linux kernel, the following vulnerability has been resolved: nilfs2: fix potential null-ptr-deref in nilfsbtreeinsert() Patch series "nilfs2: fix potential issues with empty b-tree nodes". This series addresses three potential issues with empty b-tree nodes that can occur with corrupted filesystem images, including one recently discovered by syzbot. This patch (of 3): If a b-tree is broken on the device, and the b-tree height is greater than 2 (the level of the root node is greater than 1) even if the number of child nodes of the b-tree root is 0, a NULL pointer dereference occurs in nilfsbtreeprepareinsert(), which is called from nilfsbtreeinsert(). This is because, when the number of child nodes of the b-tree root is 0, nilfsbtreedolookup() does not set the block buffer head in any of path[x].bpbh, leaving it as the initial value of NULL, but if the level of the b-tree root node is greater than 1, nilfsbtreegetnonrootnode(), which accesses the buffer memory of path[x].bpbh, is called. Fix this issue by adding a check to nilfsbtreerootbroken(), which performs sanity checks when reading the root node from the device, to detect this inconsistency. Thanks to Lizhi Xu for trying to solve the bug and clarifying the cause early on.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
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ubuntu/linux-aws-5.4to a version that resolves this vulnerability.Fixed in 5.4.0-1142.152~18.04.1 - Upgrade
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ubuntu/linux-azure-5.4to a version that resolves this vulnerability.Fixed in 5.4.0-1145.152~18.04.1 - Upgrade
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ubuntu/linux-gcp-5.4to a version that resolves this vulnerability.Fixed in 5.4.0-1143.152~18.04.1 - Upgrade
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ubuntu/linux-awsto a version that resolves this vulnerability.Fixed in 5.4.0-1140.150 - Upgrade
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ubuntu/linux-aws-5.15to a version that resolves this vulnerability.Fixed in 5.15.0-1073.79~20.04.1 - Upgrade
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ubuntu/linux-azureto a version that resolves this vulnerability.Fixed in 5.4.0-1145.152 - Upgrade
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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-bluefieldto a version that resolves this vulnerability.Fixed in 5.4.0-1099.106 - Upgrade
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ubuntu/linux-hwe-5.15to a version that resolves this vulnerability.Fixed in 5.15.0-127.137~20.04.1 - Upgrade
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ubuntu/linux-ibmto a version that resolves this vulnerability.Fixed in 5.4.0-1086.91 - Upgrade
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ubuntu/linux-ibm-5.15to a version that resolves this vulnerability.Fixed in 5.15.0-1066.69~20.04.1 - Upgrade
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ubuntu/linux-fipsto a version that resolves this vulnerability.Fixed in 5.4.0-1116.126 - Upgrade
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ubuntu/linuxto a version that resolves this vulnerability.Fixed in 5.15.0-127.137 - Upgrade
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ubuntu/linux-awsto a version that resolves this vulnerability.Fixed in 5.15.0-1073.79 - Upgrade
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ubuntu/linux-aws-6.8to a version that resolves this vulnerability.Fixed in 6.8.0-1023.25~22.04.1 - Upgrade
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ubuntu/linux-azureto a version that resolves this vulnerability.Fixed in 5.15.0-1078.87 - Upgrade
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ubuntu/linux-azure-6.8to a version that resolves this vulnerability.Fixed in 6.8.0-1025.30~22.04.1 - Upgrade
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ubuntu/linux-gcpto a version that resolves this vulnerability.Fixed in 5.15.0-1072.80 - Upgrade
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ubuntu/linux-gcp-6.8to a version that resolves this vulnerability.Fixed in 6.8.0-1024.26~22.04.1 - Upgrade
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ubuntu/linux-gketo a version that resolves this vulnerability.Fixed in 5.15.0-1070.76 - Upgrade
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ubuntu/linux-gkeopto a version that resolves this vulnerability.Fixed in 5.15.0-1056.63 - Upgrade
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ubuntu/linux-ibmto a version that resolves this vulnerability.Fixed in 5.15.0-1066.69 - Upgrade
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ubuntu/linux-intel-iotgto a version that resolves this vulnerability.Fixed in 5.15.0-1071.77 - Upgrade
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ubuntu/linux-kvmto a version that resolves this vulnerability.Fixed in 5.15.0-1070.75 - Upgrade
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ubuntu/linux-lowlatencyto a version that resolves this vulnerability.Fixed in 5.15.0-127.137 - Upgrade
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ubuntu/linux-nvidiato a version that resolves this vulnerability.Fixed in 5.15.0-1068.69 - Upgrade
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ubuntu/linux-nvidia-6.8to a version that resolves this vulnerability.Fixed in 6.8.0-1022.25~22.04.2 - Upgrade
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ubuntu/linux-nvidia-tegrato a version that resolves this vulnerability.Fixed in 5.15.0-1032.32 - Upgrade
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ubuntu/linux-nvidia-tegra-igxto a version that resolves this vulnerability.Fixed in 5.15.0-1020.20 - Upgrade
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ubuntu/linux-oracleto a version that resolves this vulnerability.Fixed in 5.15.0-1071.77 - Upgrade
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ubuntu/linux-oracle-6.8to a version that resolves this vulnerability.Fixed in 6.8.0-1020.21~22.04.1 - Upgrade
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ubuntu/linux-raspito a version that resolves this vulnerability.Fixed in 5.15.0-1066.69 - Upgrade
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ubuntu/linux-riscv-6.8to a version that resolves this vulnerability.Fixed in 6.8.0-53.55.1~22.04.1 - Upgrade
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ubuntu/linux-xilinx-zynqmpto a version that resolves this vulnerability.Fixed in 5.15.0-1039.43 - Upgrade
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ubuntu/linux-bluefieldto a version that resolves this vulnerability.Fixed in 5.15.0-1057.59 - Upgrade
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ubuntu/linux-intel-iot-realtimeto a version that resolves this vulnerability.Fixed in 5.15.0-1066.68 - Upgrade
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ubuntu/linux-azure-fipsto a version that resolves this vulnerability.Fixed in 5.15.0-1078.87+fips1 - Upgrade
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ubuntu/linux-fipsto a version that resolves this vulnerability.Fixed in 5.15.0-127.137+fips1 - Upgrade
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ubuntu/linux-gcp-fipsto a version that resolves this vulnerability.Fixed in 5.15.0-1072.80+fips1 - Upgrade
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ubuntu/linuxto a version that resolves this vulnerability.Fixed in 6.8.0-54.56 - Upgrade
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ubuntu/linux-awsto a version that resolves this vulnerability.Fixed in 6.8.0-1023.25 - Upgrade
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ubuntu/linux-azureto a version that resolves this vulnerability.Fixed in 6.8.0-1025.30 - Upgrade
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ubuntu/linux-azure-6.11to a version that resolves this vulnerability.Fixed in 6.11.0-1012.12~24.04.1 - Upgrade
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ubuntu/linux-gcpto a version that resolves this vulnerability.Fixed in 6.8.0-1024.26 - Upgrade
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ubuntu/linux-gcp-6.11to a version that resolves this vulnerability.Fixed in 6.11.0-1011.11~24.04.1 - Upgrade
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ubuntu/linux-gketo a version that resolves this vulnerability.Fixed in 6.8.0-1019.23 - Upgrade
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ubuntu/linux-gkeopto a version that resolves this vulnerability.Fixed in 6.8.0-1006.8 - Upgrade
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ubuntu/linux-ibmto a version that resolves this vulnerability.Fixed in 6.8.0-1022.22 - Upgrade
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ubuntu/linux-lowlatencyto a version that resolves this vulnerability.Fixed in 6.8.0-54.56.1 - Upgrade
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ubuntu/linux-nvidiato a version that resolves this vulnerability.Fixed in 6.8.0-1022.25 - Upgrade
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ubuntu/linux-nvidia-6.11to a version that resolves this vulnerability.Fixed in 6.11.0-1007.7 - Upgrade
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ubuntu/linux-nvidia-lowlatencyto a version that resolves this vulnerability.Fixed in 6.8.0-1022.25.2 - Upgrade
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ubuntu/linux-oem-6.11to a version that resolves this vulnerability.Fixed in 6.11.0-1015.15 - Upgrade
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ubuntu/linux-oem-6.8to a version that resolves this vulnerability.Fixed in 6.8.0-1024.24 - Upgrade
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ubuntu/linux-oracleto a version that resolves this vulnerability.Fixed in 6.8.0-1020.21 - Upgrade
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ubuntu/linux-raspito a version that resolves this vulnerability.Fixed in 6.8.0-1019.23 - Upgrade
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ubuntu/linux-riscvto a version that resolves this vulnerability.Fixed in 6.8.0-53.55.1 - Upgrade
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ubuntu/linux-xilinxto a version that resolves this vulnerability.Fixed in 6.8.0-1017.18 - Upgrade
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ubuntu/linux-raspi-realtimeto a version that resolves this vulnerability.Fixed in 6.8.0-2018.19 - Upgrade
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ubuntu/linux-realtimeto a version that resolves this vulnerability.Fixed in 6.8.1-1016.17 - Upgrade
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ubuntu/linux-fipsto a version that resolves this vulnerability.Fixed in 6.8.0-78.78+fips1 - Compensating control
Add a sanity check to nilfs_btree_root_broken() when reading the b-tree root from the device to detect the inconsistency where the root has zero child nodes while its level is greater than 1, preventing the NULL pointer dereference in nilfs_btree_prepare_insert().
Event History
Frequently Asked Questions
Who is realistically exposed to this issue?
Systems using the affected Ubuntu kernel packages are exposed when they access a corrupted NILFS2 filesystem image containing an inconsistent empty B-tree root node. The listed packages include the standard Ubuntu kernel and AWS, Azure, GCP, FIPS, AWS FIPS, and Azure FIPS variants.
What does an attacker need to trigger the vulnerability?
An attacker needs to cause the system to process a corrupted NILFS2 filesystem image with a B-tree height greater than 2 and a root node reporting zero child nodes. The supplied severity vector indicates network attack vector, low complexity, no privileges required, and user interaction required.
What is the impact if exploitation succeeds?
The flaw can cause a NULL pointer dereference in NILFS2 B-tree insertion handling, resulting in an availability impact. The provided vector indicates no confidentiality or integrity impact.
How can I determine whether a filesystem is affected?
The vulnerable condition is an inconsistent NILFS2 B-tree root read from the device: a root level greater than 1 with zero child nodes. The provided data does not identify a user-space detection command or affected package versions.