Linux Kernel up to 7.1.4 LZO Compression fs/btrfs/lzo.c lzo_decompress_bio null pointer dereference

Summaryinfo

A vulnerability was found in Linux Kernel up to 7.1.4. It has been rated as problematic. Affected is the function lzo_decompress_bio of the file fs/btrfs/lzo.c of the component LZO Compression. This manipulation causes null pointer dereference. This vulnerability is handled as CVE-2026-80631. It is possible to launch the attack on the local host. There is not any exploit available.

Detailsinfo

A vulnerability has been found in Linux Kernel up to 7.1.4 and classified as problematic. Affected by this vulnerability is the function lzo_decompress_bio of the file fs/btrfs/lzo.c of the component LZO Compression. The manipulation with an unknown input leads to a null pointer dereference vulnerability. The CWE definition for the vulnerability is CWE-476. A NULL pointer dereference occurs when the application dereferences a pointer that it expects to be valid, but is NULL, typically causing a crash or exit. As an impact it is known to affect availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: btrfs: lzo: reject compressed segment that overflows the compressed input lzo_decompress_bio() validates each on-disk segment length seg_len only against the workspace cbuf size, not against the compressed input size (compressed_len, the total folio bytes of the bio). A crafted extent can carry a segment whose seg_len passes the cbuf check but runs past the end of the bio, so copy_compressed_segment() walks off the last folio: get_current_folio() then returns the NULL folio from bio_next_folio(), and with CONFIG_BTRFS_ASSERT disabled (default) folio_size(NULL) faults. BUG: KASAN: null-ptr-deref in lzo_decompress_bio (fs/btrfs/lzo.c:383) Read of size 8 at addr 0000000000000000 by task kworker/u8:1/29 Workqueue: btrfs-endio simple_end_io_work kasan_report (mm/kasan/report.c:590) lzo_decompress_bio (fs/btrfs/lzo.c:383) end_bbio_compressed_read (fs/btrfs/compression.c:1065) btrfs_bio_end_io (fs/btrfs/bio.c:135) btrfs_check_read_bio (fs/btrfs/bio.c:180 fs/btrfs/bio.c:285) simple_end_io_work process_one_work worker_thread Reject any segment whose payload would extend beyond compressed_len before copying it, treating it as corruption like the other on-disk validation failures in this function.

It is possible to read the advisory at git.kernel.org. This vulnerability is known as CVE-2026-80631 since 08/26/2026. The exploitation appears to be easy. Attacking locally is a requirement. The exploitation needs additional levels of successful authentication. Technical details of the vulnerability are known, but there is no available exploit.

Upgrading to version 7.1.5 eliminates this vulnerability. Applying the patch 1641d058adfbd50cf95d54581ed5d142ee82c07f/b0d27d43791b7a3057c3c4aedf9b4aa033d37c46 is able to eliminate this problem.

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Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 7.1.0
• 7.1.1
• 7.1.2
• 7.1.3
• 7.1.4

License

• open-source

Website

• Vendor: https://www.kernel.org/

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