Description
In the Linux kernel, the following vulnerability has been resolved:
netfs: break unbuffered write when netfs_alloc_subrequest() fails
syzbot reported a null-ptr-deref below [1] following a fault injection in netfs_alloc_subrequest(). [0]
When netfs_alloc_subrequest() fails, subreq is NULL. Later, netfs_prepare_write() tries to initialize members of subreq(e.g., source), the issue in [1] is triggered.
Let's handle the error of netfs_prepare_write() properly.
[0] FAULT_INJECTION: forcing a failure. name failslab, interval 1, probability 0, space 0, times 0 Call Trace: netfs_alloc_subrequest+0x116/0x3f0 netfs_prepare_write+0x76/0x7b0 netfs_unbuffered_write+0x75c/0x2020 netfs_unbuffered_write_iter_locked+0x7d6/0xa80 netfs_unbuffered_write_iter+0x442/0x720 v9fs_file_write_iter+0xbf/0x100 vfs_write+0x6ac/0x1050
[1] KASAN: null-ptr-deref in range [0x00000000000000a8-0x00000000000000af] RIP: 0010:netfs_prepare_write+0xbc/0x7b0 fs/netfs/write_issue.c:173 Call Trace: netfs_unbuffered_write+0x75c/0x2020 fs/netfs/direct_write.c:111 netfs_unbuffered_write_iter_locked+0x7d6/0xa80 fs/netfs/direct_write.c:290 netfs_unbuffered_write_iter+0x442/0x720 fs/netfs/direct_write.c:382 v9fs_file_write_iter+0xbf/0x100 fs/9p/vfs_file.c:409 new_sync_write fs/read_write.c:595 [inline]
Metrics
No CVSS score has been published yet.
Affected software
Source: the vendor's advisory (CNA). NVD analysis pending.
No affected versions have been published.
Timeline
- Published
- Sep 25, 2026
- Last modified
- Oct 19, 2026
- NVD status
- Undergoing Analysis