CVE-2026-80631btrfs: lzo: reject compressed segment that overflows the compressed input

Official description

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.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/e4325fb00e0c7269cb67f97d7148507787a57fd7
• https://git.kernel.org/stable/c/d9b17f9ce67d00e48fab62dcae197612a58f625f
• https://git.kernel.org/stable/c/1c48c8c807e49ac4f72819a89035fb8d2d094015
• https://git.kernel.org/stable/c/be7fb59512ffc2da5d98214a00117dfe9eccab78
• https://git.kernel.org/stable/c/1641d058adfbd50cf95d54581ed5d142ee82c07f
• https://git.kernel.org/stable/c/b0d27d43791b7a3057c3c4aedf9b4aa033d37c46