CVE-2026-74400: bpf: fix crash in bpf_[set|remove]_dentry_xattr for negative dentries
In the Linux kernel, the following vulnerability has been resolved:
bpf: fix crash in bpf[set|remove]dentryxattr for negative dentries
bpfsetdentryxattr and bpfremovedentryxattr BPF kfuncs attempt to lock the inode of the supplied dentry without checking if it is NULL. If a negative dentry is passed (e.g. from securityinodecreate), dinode(dentry) returns NULL, and inodelock(inode) will cause a NULL pointer dereference.
Trivially fix this by adding a NULL check for inode before attempting to lock it, returning -EINVAL if it is NULL.
Additionally, drop WARNON(!inode) in bpfxattrreadpermission() and bpfxattrwritepermission(). These warnings could be triggered by passing a negative dentry to bpfgetdentryxattr() or the locked variants of the xattr kfuncs, potentially causing a Denial of Service on systems with paniconwarn enabled. Instead, simply return -EINVAL.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
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ubuntu/linux-aws-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1014.14~24.04.1 - Upgrade
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ubuntu/linux-azure-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1017.17~24.04.1 - Upgrade
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ubuntu/linux-azure-fde-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1016.16~24.04.1 - Upgrade
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ubuntu/linux-gcp-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1014.14~24.04.1 - Upgrade
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ubuntu/linux-hwe-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-38.38~24.04.4 - Upgrade
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ubuntu/linux-nvidia-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1024.25~24.04.1 - Upgrade
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ubuntu/linux-oracle-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1013.13~24.04.1 - Upgrade
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ubuntu/linux-riscv-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-38.38.1~24.04.1 - Upgrade
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ubuntu/linuxto a version that resolves this vulnerability.Fixed in 7.0.0-38.38 - Upgrade
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ubuntu/linux-awsto a version that resolves this vulnerability.Fixed in 7.0.0-1014.14 - Upgrade
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ubuntu/linux-azureto a version that resolves this vulnerability.Fixed in 7.0.0-1017.17 - Upgrade
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ubuntu/linux-azure-fdeto a version that resolves this vulnerability.Fixed in 7.0.0-1016.16 - Upgrade
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ubuntu/linux-gcpto a version that resolves this vulnerability.Fixed in 7.0.0-1014.14 - Upgrade
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ubuntu/linux-gketo a version that resolves this vulnerability.Fixed in 7.0.0-1008.9 - Upgrade
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ubuntu/linux-ibmto a version that resolves this vulnerability.Fixed in 7.0.0-1015.15 - Upgrade
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ubuntu/linux-nvidia-bosto a version that resolves this vulnerability.Fixed in 7.0.0-2022.23 - Upgrade
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ubuntu/linux-oem-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1015.15 - Upgrade
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ubuntu/linux-oracleto a version that resolves this vulnerability.Fixed in 7.0.0-1013.13 - Upgrade
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ubuntu/linux-realtimeto a version that resolves this vulnerability.Fixed in 7.0.0-38.38.1 - Upgrade
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ubuntu/linux-riscvto a version that resolves this vulnerability.Fixed in 7.0.0-38.38.1
Event History
Frequently Asked Questions
What is the severity of CVE-2026-74400?
CVE-2026-74400 has a risk score of 21, indicating a critical severity level.
What does CVE-2026-74400 affect?
CVE-2026-74400 affects the Linux kernel, specifically the BPF functions handling dentry xattrs.
How do I fix CVE-2026-74400?
To fix CVE-2026-74400, update your Linux kernel to the patched version that addresses this vulnerability.
What kind of vulnerability is CVE-2026-74400?
CVE-2026-74400 is classified as a Null Pointer Dereference vulnerability.
What is the main issue described in CVE-2026-74400?
The main issue in CVE-2026-74400 is the potential crash of BPF functions due to dereferencing a NULL inode pointer.