net: skbuff: fix missing zerocopy reference in pskb_carve helpers

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Summary

CVECVE-2026-52943
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-06-24 10:17:19 UTC
Updated2026-06-24 10:17:19 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: net: skbuff: fix missing zerocopy reference in pskb_carve helpers pskb_carve_inside_header() and pskb_carve_inside_nonlinear() both copy the old skb_shared_info header into a new buffer via memcpy(), which includes the destructor_arg pointer (uarg) for MSG_ZEROCOPY skbs. Neither function calls net_zcopy_get() for the new shinfo, creating an unaccounted holder: every skb_shared_info with destructor_arg set will call skb_zcopy_clear() once when freed, but the corresponding net_zcopy_get() was never called for the new copy. Repeated calls drive uarg->refcnt to zero prematurely, freeing ubuf_info_msgzc while TX skbs still hold live destructor_arg pointers. KASAN reports use-after-free on a freed ubuf_info_msgzc: BUG: KASAN: slab-use-after-free in skb_release_data+0x77b/0x810 Read of size 8 at addr ffff88801574d3e8 by task poc/220 Call Trace: skb_release_data+0x77b/0x810 kfree_skb_list_reason+0x13e/0x610 skb_release_data+0x4cd/0x810 sk_skb_reason_drop+0xf3/0x340 skb_queue_purge_reason+0x282/0x440 rds_tcp_inc_free+0x1e/0x30 rds_recvmsg+0x354/0x1780 __sys_recvmsg+0xdf/0x180 Allocated by task 219: msg_zerocopy_realloc+0x157/0x7b0 tcp_sendmsg_locked+0x2892/0x3ba0 Freed by task 219: ip_recv_error+0x74a/0xb10 tcp_recvmsg+0x475/0x530 The skb consuming the late access still referenced the same uarg via shinfo->destructor_arg copied by pskb_carve_inside_nonlinear() without a refcount bump. This has been verified to be reliably exploitable: a working proof-of-concept achieves full root privilege escalation from an unprivileged local user on a default kernel configuration. The fix follows the pattern of pskb_expand_head() which has the same memcpy/cloned structure. For pskb_carve_inside_header(), net_zcopy_get() is placed after skb_orphan_frags() succeeds, so the orphan error path needs no cleanup. For pskb_carve_inside_nonlinear(), net_zcopy_get() is placed after all failure points and just before skb_release_data(), so no error path needs cleanup at all -- matching pskb_expand_head() more closely and avoiding the need for a balancing net_zcopy_put().

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 6fa01ccd883021105e9f8af7d04b9f156fa3494a 8dbed691e43a50903658130bde0fcb5abc425b37 git Not specified
CNA Linux Linux affected 6fa01ccd883021105e9f8af7d04b9f156fa3494a 9b40bdc2a3298225dffab8158208a0d8c6300578 git Not specified
CNA Linux Linux affected 6fa01ccd883021105e9f8af7d04b9f156fa3494a fd470f0a97b8e9a125f520265d2f3b088ffb5b8a git Not specified
CNA Linux Linux affected 6fa01ccd883021105e9f8af7d04b9f156fa3494a ceafb893b12f23331dcc5ff9587e643c3a40ee9f git Not specified
CNA Linux Linux affected 6fa01ccd883021105e9f8af7d04b9f156fa3494a 2e0e74c59b2761a414d9f48d7bee1e45220b2427 git Not specified
CNA Linux Linux affected 6fa01ccd883021105e9f8af7d04b9f156fa3494a 96a4713ae041cc85e712bac682cd2e644004d6c6 git Not specified
CNA Linux Linux affected 6fa01ccd883021105e9f8af7d04b9f156fa3494a 474d6c771d798bca84f0a140b611e36743511e18 git Not specified
CNA Linux Linux affected 6fa01ccd883021105e9f8af7d04b9f156fa3494a 98d0912e9f841e5529a5b89a972805f34cb1c69d git Not specified
CNA Linux Linux affected 4.7 Not specified
CNA Linux Linux unaffected 4.7 semver Not specified
CNA Linux Linux unaffected 5.10.259 5.10.* semver Not specified
CNA Linux Linux unaffected 5.15.210 5.15.* semver Not specified
CNA Linux Linux unaffected 6.1.176 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.143 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.93 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.35 6.18.* semver Not specified
CNA Linux Linux unaffected 7.0.12 7.0.* semver Not specified
CNA Linux Linux unaffected 7.1 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/ceafb893b12f23331dcc5ff9587e643c3a40ee9f 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/9b40bdc2a3298225dffab8158208a0d8c6300578 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/2e0e74c59b2761a414d9f48d7bee1e45220b2427 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/474d6c771d798bca84f0a140b611e36743511e18 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/fd470f0a97b8e9a125f520265d2f3b088ffb5b8a 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/8dbed691e43a50903658130bde0fcb5abc425b37 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/96a4713ae041cc85e712bac682cd2e644004d6c6 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/98d0912e9f841e5529a5b89a972805f34cb1c69d 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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