Advisory [CVE-2026-63816] fix UAF issue on f2fs_inode_info.atomic_inode
This security Red Hat Linux advisory covers CVE-2026-63816.
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Summary
In the Linux kernel, the following vulnerability has been resolved: f2fs: atomic: fix UAF issue on f2fs_inode_info.atomic_inode - ioctl(F2FS_IOC_GARBAGE_COLLECT_RANGE)- shrink - f2fs_gc - gc_data_segment - ra_data_block(cow_inode) - mapping = F2FS_I(inode)->atomic_inode->i_mapping: f2fs_is_cow_file(cow_inode) is true - f2fs_evict_inode(atomic_inode) - clear_inode_flag(fi->cow_inode, FI_COW_FILE) - F2FS_I(fi->cow_inode)->atomic_inode = NULL... - truncate_inode_pages_final(atomic_inode) - f2fs_grab_cache_folio(mapping): create folio in atomic_inode->mapping - clear_inode(atomic_inode) - BUG_ON(atomic_inode->i_data.nrpages) We need to add a reference on fi->atomic_inode before using its mapping field during garbage collection, otherwise, it will cause UAF issue.
A flaw was found in the f2fs (Flash-Friendly File System) component of the Linux kernel. This use-after-free (UAF) vulnerability occurs during garbage collection operations when handling Copy-On-Write (COW) files.
A local attacker could exploit this by triggering garbage collection, leading to a premature deallocation of memory. Subsequent access to this freed memory could result in a system crash, causing a Denial of Service (DoS), or potentially lead to privilege escalation.
Red Hat severity: not rated. Weakness: CWE-825.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.
Official advisory · medium-confidence parse· fetched 7 days ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · medium-confidence parse· fetched 7 days ago·verify at source
Mitigation
The source record does not include mitigation steps. That is not a statement that no fix exists — read the vendor advisory below for the authoritative guidance.
Official advisory · medium-confidence parse· fetched 7 days ago·verify at source
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