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]
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | ||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Linux | Linux | unaffected |
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| Linux | Linux | affected |
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| Vendors | Products |
|---|---|
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Linux
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Linux Kernel
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Solution
No solution given by the vendor.
Workaround
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Fri, 25 Sep 2026 12:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Weaknesses | CWE-476 |
Fri, 25 Sep 2026 10:45:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| 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] | |
| Title | netfs: break unbuffered write when netfs_alloc_subrequest() fails | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
|
Projects
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MITRE
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-09-25T10:36:03.524Z
Reserved: 2026-09-25T10:25:14.317Z
Link: CVE-2026-98119
Vulnrichment
No data.
NVD
Status : Received
Published: 2026-09-25T11:17:43.140
Modified: 2026-09-25T11:17:43.140
Link: CVE-2026-98119
Redhat
No data.
OpenCVE Enrichment
Updated: 2026-09-25T13:45:18Z