---
cve: "CVE-2024-39301"
severity: "LOW"
cvss: 3.1
epss: "23%"
vendor: "Linux"
kev: false
exploited: false
published: "2024-06-25 15:15:14"
tags: [cve, security, low]
source: tsecurity.de CVE-Dossier
exported: "2026-09-14T16:32:42+02:00"
---

# CVE-2024-39301

> 3.1 LOW

## Beschreibung

In the Linux kernel, the following vulnerability has been resolved:

net/9p: fix uninit-value in p9_client_rpc()

Syzbot with the help of KMSAN reported the following error:

BUG: KMSAN: uninit-value in trace_9p_client_res include/trace/events/9p.h:146 [inline]
BUG: KMSAN: uninit-value in p9_client_rpc+0x1314/0x1340 net/9p/client.c:754
 trace_9p_client_res include/trace/events/9p.h:146 [inline]
 p9_client_rpc+0x1314/0x1340 net/9p/client.c:754
 p9_client_create+0x1551/0x1ff0 net/9p/client.c:1031
 v9fs_session_init+0x1b9/0x28e0 fs/9p/v9fs.c:410
 v9fs_mount+0xe2/0x12b0 fs/9p/vfs_super.c:122
 legacy_get_tree+0x114/0x290 fs/fs_context.c:662
 vfs_get_tree+0xa7/0x570 fs/super.c:1797
 do_new_mount+0x71f/0x15e0 fs/namespace.c:3352
 path_mount+0x742/0x1f20 fs/namespace.c:3679
 do_mount fs/namespace.c:3692 [inline]
 __do_sys_mount fs/namespace.c:3898 [inline]
 __se_sys_mount+0x725/0x810 fs/namespace.c:3875
 __x64_sys_mount+0xe4/0x150 fs/namespace.c:3875
 do_syscall_64+0xd5/0x1f0
 entry_SYSCALL_64_after_hwframe+0x6d/0x75

Uninit was created at:
 __alloc_pages+0x9d6/0xe70 mm/page_alloc.c:4598
 __alloc_pages_node include/linux/gfp.h:238 [inline]
 alloc_pages_node include/linux/gfp.h:261 [inline]
 alloc_slab_page mm/slub.c:2175 [inline]
 allocate_slab mm/slub.c:2338 [inline]
 new_slab+0x2de/0x1400 mm/slub.c:2391
 ___slab_alloc+0x1184/0x33d0 mm/slub.c:3525
 __slab_alloc mm/slub.c:3610 [inline]
 __slab_alloc_node mm/slub.c:3663 [inline]
 slab_alloc_node mm/slub.c:3835 [inline]
 kmem_cache_alloc+0x6d3/0xbe0 mm/slub.c:3852
 p9_tag_alloc net/9p/client.c:278 [inline]
 p9_client_prepare_req+0x20a/0x1770 net/9p/client.c:641
 p9_client_rpc+0x27e/0x1340 net/9p/client.c:688
 p9_client_create+0x1551/0x1ff0 net/9p/client.c:1031
 v9fs_session_init+0x1b9/0x28e0 fs/9p/v9fs.c:410
 v9fs_mount+0xe2/0x12b0 fs/9p/vfs_super.c:122
 legacy_get_tree+0x114/0x290 fs/fs_context.c:662
 vfs_get_tree+0xa7/0x570 fs/super.c:1797
 do_new_mount+0x71f/0x15e0 fs/namespace.c:3352
 path_mount+0x742/0x1f20 fs/namespace.c:3679
 do_mount fs/namespace.c:3692 [inline]
 __do_sys_mount fs/namespace.c:3898 [inline]
 __se_sys_mount+0x725/0x810 fs/namespace.c:3875
 __x64_sys_mount+0xe4/0x150 fs/namespace.c:3875
 do_syscall_64+0xd5/0x1f0
 entry_SYSCALL_64_after_hwframe+0x6d/0x75

If p9_check_errors() fails early in p9_client_rpc(), req->rc.tag
will not be properly initialized. However, trace_9p_client_res()
ends up trying to print it out anyway before p9_client_rpc()
finishes.

Fix this issue by assigning default values to p9_fcall fields
such as 'tag' and (just in case KMSAN unearths something new) 'id'
during the tag allocation stage.

## Patch verfügbar (OSV)

- Kernel ≥ 4.19.316
- Kernel ≥ 5.4.278
- Kernel ≥ 5.10.219
- Kernel ≥ 5.15.161
- Kernel ≥ 6.1.94
- Kernel ≥ 6.6.34
- Kernel ≥ 6.9.5

## Referenzen

- <https://git.kernel.org/stable/c/72c5d8e416ecc46af370a1340b3db5ff0b0cc867>
- <https://git.kernel.org/stable/c/2101901dd58c6da4924bc5efb217a1d83436290b>
- <https://git.kernel.org/stable/c/124947855564572713d705a13be7d0c9dae16a17>
- <https://git.kernel.org/stable/c/89969ffbeb948ffc159d19252e7469490103011b>
- <https://git.kernel.org/stable/c/ca71f204711ad24113e8b344dc5bb8b0385f5672>
- <https://git.kernel.org/stable/c/6c1791130b781c843572fb6391c4a4c5d857ab17>
- <https://git.kernel.org/stable/c/fe5c604053c36c62af24eee8a76407d026ea5163>
- <https://git.kernel.org/stable/c/25460d6f39024cc3b8241b14c7ccf0d6f11a736a>

---
_Exportiert aus dem [tsecurity.de CVE-Dossier](https://tsecurity.de/cve?cve=CVE-2024-39301) · Datenquellen: EUVD (ENISA), NVD, OSV, CISA KEV, FIRST EPSS, Exploit-DB, BSI BITS_
