# CVE-2024-36927

## Summary

- **CVE ID:** CVE-2024-36927
- **Severity:** MEDIUM
- **CVSS Score:** 4.7 (CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H)
- **CWE:** N/A
- **Published:** May 30, 2024
- **Last Modified:** Sep 8, 2026

## Description

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

ipv4: Fix uninit-value access in __ip_make_skb()

KMSAN reported uninit-value access in __ip_make_skb() [1].  __ip_make_skb()
tests HDRINCL to know if the skb has icmphdr. However, HDRINCL can cause a
race condition. If calling setsockopt(2) with IP_HDRINCL changes HDRINCL
while __ip_make_skb() is running, the function will access icmphdr in the
skb even if it is not included. This causes the issue reported by KMSAN.

Check FLOWI_FLAG_KNOWN_NH on fl4->flowi4_flags instead of testing HDRINCL
on the socket.

Also, fl4->fl4_icmp_type and fl4->fl4_icmp_code are not initialized. These
are union in struct flowi4 and are implicitly initialized by
flowi4_init_output(), but we should not rely on specific union layout.

Initialize these explicitly in raw_sendmsg().

[1]
BUG: KMSAN: uninit-value in __ip_make_skb+0x2b74/0x2d20 net/ipv4/ip_output.c:1481
 __ip_make_skb+0x2b74/0x2d20 net/ipv4/ip_output.c:1481
 ip_finish_skb include/net/ip.h:243 [inline]
 ip_push_pending_frames+0x4c/0x5c0 net/ipv4/ip_output.c:1508
 raw_sendmsg+0x2381/0x2690 net/ipv4/raw.c:654
 inet_sendmsg+0x27b/0x2a0 net/ipv4/af_inet.c:851
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg+0x274/0x3c0 net/socket.c:745
 __sys_sendto+0x62c/0x7b0 net/socket.c:2191
 __do_sys_sendto net/socket.c:2203 [inline]
 __se_sys_sendto net/socket.c:2199 [inline]
 __x64_sys_sendto+0x130/0x200 net/socket.c:2199
 do_syscall_64+0xd8/0x1f0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x6d/0x75

Uninit was created at:
 slab_post_alloc_hook mm/slub.c:3804 [inline]
 slab_alloc_node mm/slub.c:3845 [inline]
 kmem_cache_alloc_node+0x5f6/0xc50 mm/slub.c:3888
 kmalloc_reserve+0x13c/0x4a0 net/core/skbuff.c:577
 __alloc_skb+0x35a/0x7c0 net/core/skbuff.c:668
 alloc_skb include/linux/skbuff.h:1318 [inline]
 __ip_append_data+0x49ab/0x68c0 net/ipv4/ip_output.c:1128
 ip_append_data+0x1e7/0x260 net/ipv4/ip_output.c:1365
 raw_sendmsg+0x22b1/0x2690 net/ipv4/raw.c:648
 inet_sendmsg+0x27b/0x2a0 net/ipv4/af_inet.c:851
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg+0x274/0x3c0 net/socket.c:745
 __sys_sendto+0x62c/0x7b0 net/socket.c:2191
 __do_sys_sendto net/socket.c:2203 [inline]
 __se_sys_sendto net/socket.c:2199 [inline]
 __x64_sys_sendto+0x130/0x200 net/socket.c:2199
 do_syscall_64+0xd8/0x1f0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x6d/0x75

CPU: 1 PID: 15709 Comm: syz-executor.7 Not tainted 6.8.0-11567-gb3603fcb79b1 #25
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-1.fc39 04/01/2014

## Affected Products

- Linux — Linux (566785731c6dd41ef815196ddc36d1ae30a63763)
- Linux — Linux (a54ec573d9b81b05d368f8e6edc1b3e49f688658)
- Linux — Linux (fc60067260c20da8cddcf968bec47416f3e2cde2)
- Linux — Linux (99e5acae193e369b71217efe6f1dad42f3f18815)
- Linux — Linux (dc4e3bb0710178c8d03fc43064e0a71fe7440cdd)
- Linux — Linux (022ea4374c319690c804706bda9dc42946d1556d)
- Linux — Linux (27c468ec1af113f6ae94fb5378f65e6038bd16e7)
- Linux — Linux (32a5a13d556e4f804e5a447a08c70b172d600707)
- Linux — Linux (9e3c96aed8fe32907e0a4bca05aad457629a820c)
- Linux — Linux (6.4)
- Linux — Linux (0)
- Linux — Linux (5.10.248)
- Linux — Linux (5.15.198)
- Linux — Linux (6.1.140)
- Linux — Linux (6.6.31)
- Linux — Linux (6.8.10)
- Linux — Linux (6.9)
- Linux — Linux (5.10.180)
- Linux — Linux (5.15.111)
- Linux — Linux (6.1.28)
- Linux — Linux (4.14.315)
- Linux — Linux (4.19.283)
- Linux — Linux (5.4.243)
- Linux — Linux (6.2.15)
- Linux — Linux (6.3.2)

## References

- [CNA](https://git.kernel.org/stable/c/88c66f1879f322f11de34d37b2d3d87497afdcb6)
- [CNA](https://git.kernel.org/stable/c/20d3eb00ab81462d554ac6d09691b8d9aa5a5741)
- [CNA](https://git.kernel.org/stable/c/55bf541e018b76b3750cb6c6ea18c46e1ac5562e)
- [CNA](https://git.kernel.org/stable/c/5db08343ddb1b239320612036c398e4e1bb52818)
- [CNA](https://git.kernel.org/stable/c/f5c603ad4e6fcf42f84053e882ebe20184bb309e)
- [CNA](https://git.kernel.org/stable/c/fc1092f51567277509563800a3c56732070b6aa4)
- [CVE](https://lists.debian.org/debian-lts-announce/2025/08/msg00010.html)
- [siemens-SADP](https://cert-portal.siemens.com/productcert/html/ssa-019113.html)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.17%
- **EPSS Percentile:** 6.7

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-17._