UBUNTU-CVE-2026-90320: Use After Free
In the Linux kernel, the following vulnerability has been resolved: ocfs2: validate external xattr entries when reading metadata ocfs2validatexattrblock() checks the xattr block header before the block reaches higher-level xattr users, but it does not verify that a non-indexed block's xhcount and entry offsets fit inside the block. Indexed buckets likewise reach list/get consumers after ECC without an entry-bounds check. Use the flat xattr entry validator for non-indexed external xattr blocks, and use a bucket-specific validator for indexed buckets at metadata read time. The bucket validator keeps the entry array bounded by the first bucket block while checking name/value offsets against the bucket block they target. Reject corrupted external xattr metadata before listxattr() or getxattr() can walk out-of-range entry arrays or name/value offsets. Validation reproduced this kernel report: BUG: KASAN: use-after-free in ocfs2xattrlistentries+0xd7/0x190 Read of size 1 at addr ffff88810a654007 by task ocfs2xattrlis/630 Call Trace: dumpstacklvl+0x66/0xa0 printreport+0xce/0x630 kasanreport+0xe0/0x110 ocfs2xattrlistentries+0xd7/0x190 ocfs2listxattr+0x3f6/0x610 listxattr+0x90/0xe0 pathlistxattrat+0xed/0x220 dosyscall64+0x115/0x6a0 entrySYSCALL64afterhwframe+0x77/0x7f
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
ubuntu/linux-hwe-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-42.42~24.04.1 - Upgrade
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ubuntu/linux-riscv-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-42.42.1~24.04.1 - Upgrade
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ubuntu/linuxto a version that resolves this vulnerability.Fixed in 7.0.0-42.42 - Upgrade
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ubuntu/linux-awsto a version that resolves this vulnerability.Fixed in 7.0.0-1016.17 - Upgrade
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ubuntu/linux-gcpto a version that resolves this vulnerability.Fixed in 7.0.0-1016.18 - Upgrade
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ubuntu/linux-ibmto a version that resolves this vulnerability.Fixed in 7.0.0-1017.17 - Upgrade
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ubuntu/linux-oem-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1017.17 - Upgrade
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ubuntu/linux-oracleto a version that resolves this vulnerability.Fixed in 7.0.0-1015.16 - Upgrade
Upgrade
ubuntu/linux-riscvto a version that resolves this vulnerability.Fixed in 7.0.0-42.42.1
Event History
Frequently Asked Questions
Which Ubuntu kernel packages are identified as affected?
The affected software list includes ubuntu/linux, ubuntu/linux-fips, ubuntu/linux-aws, ubuntu/linux-azure, ubuntu/linux-aws-fips, ubuntu/linux-azure-fips, ubuntu/linux-gcp, and ubuntu/linux-gcp-fips.
What filesystem condition is involved in triggering the issue?
The issue involves corrupted external OCFS2 extended-attribute metadata, including non-indexed xattr blocks and indexed xattr buckets with out-of-range entry arrays or name/value offsets.
Which operations can reach the vulnerable metadata handling?
The vulnerable paths can be reached when listxattr() or getxattr() processes the malformed external xattr metadata. The reported KASAN use-after-free occurred in ocfs2_xattr_list_entries during listxattr handling.
What is the impact observed in the report?
The reproduced report shows a KASAN-detected use-after-free read. The severity vector indicates availability impact, with no stated confidentiality or integrity impact.