DEBIAN-CVE-2026-63811

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Source

https://security-tracker.debian.org/tracker/CVE-2026-63811

Import Source

https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2026-63811.json

JSON Data

https://api.test.osv.dev/v1/vulns/DEBIAN-CVE-2026-63811

Upstream

CVE-2026-63811

Published

2026-07-19T12:16:54Z

Modified

2026-08-27T22:49:02Z

Summary

[none]

Details

In the Linux kernel, the following vulnerability has been resolved: f2fs: read COW data with the original inode during atomic write When updating an atomic-write file, f2fs_write_begin() may read the previously written data back from the COW inode: prepare_atomic_write_begin() locates the block in the COW inode and sets use_cow, and the read bio is then built with the COW inode: f2fs_submit_page_read(use_cow ? F2FS_I(inode)->cow_inode : inode, ...); and f2fs_grab_read_bio() decides whether to schedule fs-layer decryption (STEP_DECRYPT) for the bio based on that inode via fscrypt_inode_uses_fs_layer_crypto(). However, the folio being filled belongs to the original inode (folio->mapping->host == inode), and the data stored in the COW block was encrypted (or left as plaintext) using the original inode's context, not the COW inode's -- see f2fs_encrypt_one_page(), which keys off fio->page->mapping->host. fscrypt_decrypt_pagecache_blocks() likewise operates on folio->mapping->host. The COW inode is created as a tmpfile in the parent directory and inherits its encryption policy from there. With test_dummy_encryption the newly created COW inode gets the dummy policy and becomes encrypted, while a pre-existing regular file -- created before the policy applied, e.g. already present in the on-disk image -- stays unencrypted. The read path then sets STEP_DECRYPT based on the encrypted COW inode and calls fscrypt_decrypt_pagecache_blocks() on a folio whose host (the unencrypted original inode) has a NULL ->i_crypt_info, dereferencing it: Oops: general protection fault, probably for non-canonical address ... KASAN: null-ptr-deref in range [0x0000000000000008-0x000000000000000f] RIP: 0010:fscrypt_decrypt_pagecache_blocks+0xa0/0x310 Workqueue: f2fs_post_read_wq f2fs_post_read_work Call Trace: fscrypt_decrypt_bio+0x1eb/0x340 f2fs_post_read_work+0xba/0x140 process_one_work+0x91c/0x1a40 worker_thread+0x677/0xe90 kthread+0x2bc/0x3a0 The COW inode is only needed to locate the on-disk block, and that block address is already resolved into @blkaddr by prepare_atomic_write_begin() via __find_data_block(cow_inode, ...); f2fs_submit_page_read() then reads from that physical @blkaddr directly, so the inode argument only selects the post-read crypto context, not which block is fetched. Reading with @inode therefore returns the same (latest, not-yet-committed) COW data, while making both the fs-layer decryption decision and the inline crypto path use the correct (original inode's) key. With the COW inode no longer used at the read site, the use_cow flag has no remaining consumer; drop it from f2fs_write_begin() and prepare_atomic_write_begin().

References

https://security-tracker.debian.org/tracker/CVE-2026-63811

Affected packages

Debian:13 / linux

Package

Name: linux
Purl: pkg:deb/debian/linux?arch=source&distro=trixie

Affected ranges

Type: ECOSYSTEM
Events: Introduced

0 Unknown introduced version / All previous versions are affected

Affected versions

6.*

6.12.38-1

6.12.41-1

6.12.43-1~bpo12+1

6.12.43-1

6.12.48-1

6.12.57-1~bpo12+1

6.12.57-1

6.12.63-1~bpo12+1

6.12.63-1

6.12.69-1~bpo12+1

6.12.69-1

6.12.73-1~bpo12+1

6.12.73-1

6.12.74-1

6.12.74-2~bpo12+1

6.12.74-2

6.12.85-1~bpo12+1

6.12.85-1

6.12.86-1~bpo12+1

6.12.86-1

6.12.88-1~bpo12+1

6.12.88-1

6.12.90-1~bpo12+1

6.12.90-1

6.12.90-2~bpo12+1

6.12.90-2

6.12.94-1~bpo12+1

6.12.94-1

6.12.95-1~bpo12+1

6.12.95-1

6.12.96-1

6.12.100-1

6.12.101-1

6.12.105-1

6.13~rc6-1~exp1

6.13~rc7-1~exp1

6.13.2-1~exp1

6.13.3-1~exp1

6.13.4-1~exp1

6.13.5-1~exp1

6.13.6-1~exp1

6.13.7-1~exp1

6.13.8-1~exp1

6.13.9-1~exp1

6.13.10-1~exp1

6.13.11-1~exp1

6.14.3-1~exp1

6.14.5-1~exp1

6.14.6-1~exp1

6.15~rc7-1~exp1

6.15-1~exp1

6.15.1-1~exp1

6.15.2-1~exp1

6.15.3-1~exp1

6.15.4-1~exp1

6.15.5-1~exp1

6.15.6-1~exp1

6.16~rc7-1~exp1

6.16-1~exp1

6.16.1-1~exp1

6.16.3-1~bpo13+1

6.16.3-1

6.16.5-1

6.16.6-1

6.16.7-1

6.16.8-1

6.16.9-1

6.16.10-1

6.16.11-1

6.16.12-1~bpo13+1

6.16.12-1

6.16.12-2

6.17.2-1~exp1

6.17.5-1~exp1

6.17.6-1

6.17.7-1

6.17.7-2

6.17.8-1~bpo13+1

6.17.8-1

6.17.9-1

6.17.10-1

6.17.11-1

6.17.12-1

6.17.13-1~bpo13+1

6.17.13-1

6.18~rc4-1~exp1

6.18~rc4-1~exp2

6.18~rc5-1~exp1

6.18~rc6-1~exp1

6.18~rc7-1~exp1

6.18.1-1~exp1

6.18.2-1~exp1

6.18.3-1

6.18.5-1~bpo13+1

6.18.5-1

6.18.8-1

6.18.9-1~bpo13+1

6.18.9-1

6.18.10-1

6.18.12-1~bpo13+1

6.18.12-1

6.18.13-1

6.18.14-1

6.18.15-1~bpo13+1

6.18.15-1

6.19~rc4-1~exp1

6.19~rc5-1~exp1

6.19~rc6-1~exp1

6.19~rc7-1~exp1

6.19~rc8-1~exp1

6.19-1~exp1

6.19.2-1~exp1

6.19.3-1~exp1

6.19.4-1~exp1

6.19.5-1~exp1

6.19.6-1

6.19.6-2~bpo13+1

6.19.6-2

6.19.8-1~bpo13+1

6.19.8-1

6.19.10-1~bpo13+1

6.19.10-1

6.19.11-1~bpo13+1

6.19.11-1

6.19.12-1

6.19.13-1~bpo13+1

6.19.13-1

6.19.14-1~bpo13+1

6.19.14-1

7.*

7.0-1~exp1

7.0.1-1~exp1

7.0.3-1

7.0.4-1~bpo13+1

7.0.4-1

7.0.7-1~bpo13+1

7.0.7-1

7.0.9-1~bpo13+1

7.0.9-1

7.0.10-1~bpo13+1

7.0.10-1

7.0.12-1

7.0.12-2~bpo13+1

7.0.12-2

7.0.13-1~bpo13+1

7.0.13-1

7.0.14-1

7.1~rc2-1~exp1

7.1~rc3-1~exp1

7.1~rc4-1~exp1

7.1~rc4-1~exp2

7.1~rc5-1~exp1

7.1~rc7-1~exp1

7.1.1-1~exp1

7.1.2-1~exp1

7.1.3-1~bpo13+1

7.1.3-1

7.1.3-1+sunvdc

7.1.4-1

7.1.5-1

7.1.6-1

7.1.7-1~bpo13+1

7.1.7-1

7.1.8-1~bpo13+1

7.1.8-1

7.1.8-2

7.1.9-1

7.1.9-1+sparc64

7.1.10-1

7.2~rc3-1~exp1

7.2~rc5-1~exp1

7.2~rc7-1~exp1

Ecosystem specific

{
    "urgency":  "not yet assigned"
}

Database specific

source

"https://storage.googleapis.com/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2026-63811.json"

Debian:14 / linux