{"id":"CVE-2026-52943","revision":"746380aaae5541e383eb3bc15b21bd54","records":[{"revision":"746380aaae5541e383eb3bc15b21bd54","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-52943","aliases":[],"title":"net: skbuff: fix missing zerocopy reference in pskb_carve helpers","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: skbuff: fix missing zerocopy reference in pskb_carve helpers\n\npskb_carve_inside_header() and pskb_carve_inside_nonlinear() both copy\nthe old skb_shared_info header into a new buffer via memcpy(), which\nincludes the destructor_arg pointer (uarg) for MSG_ZEROCOPY skbs.\nNeither function calls net_zcopy_get() for the new shinfo, creating an\nunaccounted holder: every skb_shared_info with destructor_arg set will\ncall skb_zcopy_clear() once when freed, but the corresponding\nnet_zcopy_get() was never called for the new copy. Repeated calls\ndrive uarg->refcnt to zero prematurely, freeing ubuf_info_msgzc while\nTX skbs still hold live destructor_arg pointers.\n\nKASAN reports use-after-free on a freed ubuf_info_msgzc:\n\n BUG: KASAN: slab-use-after-free in skb_release_data+0x77b/0x810\n Read of size 8 at addr ffff88801574d3e8 by task poc/220\n\n Call Trace:\n skb_release_data+0x77b/0x810\n kfree_skb_list_reason+0x13e/0x610\n skb_release_data+0x4cd/0x810\n sk_skb_reason_drop+0xf3/0x340\n skb_queue_purge_reason+0x282/0x440\n rds_tcp_inc_free+0x1e/0x30\n rds_recvmsg+0x354/0x1780\n __sys_recvmsg+0xdf/0x180\n\n Allocated by task 219:\n msg_zerocopy_realloc+0x157/0x7b0\n tcp_sendmsg_locked+0x2892/0x3ba0\n\n Freed by task 219:\n ip_recv_error+0x74a/0xb10\n tcp_recvmsg+0x475/0x530\n\nThe skb consuming the late access still referenced the same uarg via\nshinfo->destructor_arg copied by pskb_carve_inside_nonlinear() without\na refcount bump. This has been verified to be reliably exploitable: a\nworking proof-of-concept achieves full root privilege escalation from\nan unprivileged local user on a default kernel configuration.\n\nThe fix follows the pattern of pskb_expand_head() which has the same\nmemcpy/cloned structure. For pskb_carve_inside_header(), net_zcopy_get()\nis placed after skb_orphan_frags() succeeds, so the orphan error path\nneeds no cleanup. For pskb_carve_inside_nonlinear(), net_zcopy_get() is\nplaced after all failure points and just before skb_release_data(), so\nno error path needs cleanup at all -- matching pskb_expand_head() more\nclosely and avoiding the need for a balancing net_zcopy_put().","state":0,"publishedAt":"2026-06-24T09:00:12.292+00:00","modifiedAt":"2026-10-19T19:47:08.739+00:00","affected":[{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n \"product\": \"Linux\",\n \"vendor\": \"Linux\",\n \"defaultStatus\": \"unaffected\",\n \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n \"programFiles\": [\n \"net/core/skbuff.c\"\n ],\n \"versions\": [\n {\n \"version\": \"6fa01ccd883021105e9f8af7d04b9f156fa3494a\",\n \"lessThan\": \"8dbed691e43a50903658130bde0fcb5abc425b37\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"6fa01ccd883021105e9f8af7d04b9f156fa3494a\",\n \"lessThan\": \"9b40bdc2a3298225dffab8158208a0d8c6300578\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"6fa01ccd883021105e9f8af7d04b9f156fa3494a\",\n \"lessThan\": \"fd470f0a97b8e9a125f520265d2f3b088ffb5b8a\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"6fa01ccd883021105e9f8af7d04b9f156fa3494a\",\n \"lessThan\": \"ceafb893b12f23331dcc5ff9587e643c3a40ee9f\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"6fa01ccd883021105e9f8af7d04b9f156fa3494a\",\n \"lessThan\": \"2e0e74c59b2761a414d9f48d7bee1e45220b2427\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"6fa01ccd883021105e9f8af7d04b9f156fa3494a\",\n \"lessThan\": \"96a4713ae041cc85e712bac682cd2e644004d6c6\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"6fa01ccd883021105e9f8af7d04b9f156fa3494a\",\n \"lessThan\": \"474d6c771d798bca84f0a140b611e36743511e18\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"6fa01ccd883021105e9f8af7d04b9f156fa3494a\",\n \"lessThan\": \"98d0912e9f841e5529a5b89a972805f34cb1c69d\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n }\n ]\n }"},{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n \"product\": \"Linux\",\n \"vendor\": \"Linux\",\n \"defaultStatus\": \"affected\",\n \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n \"programFiles\": [\n \"net/core/skbuff.c\"\n ],\n \"versions\": [\n {\n \"version\": \"4.7\",\n \"status\": \"affected\"\n },\n {\n \"version\": \"0\",\n \"lessThan\": \"4.7\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"5.10.259\",\n \"lessThanOrEqual\": \"5.10.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"5.15.210\",\n \"lessThanOrEqual\": \"5.15.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.1.176\",\n \"lessThanOrEqual\": \"6.1.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.6.143\",\n \"lessThanOrEqual\": \"6.6.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.12.93\",\n \"lessThanOrEqual\": \"6.12.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.18.35\",\n \"lessThanOrEqual\": \"6.18.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"7.0.12\",\n \"lessThanOrEqual\": \"7.0.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"7.1\",\n \"lessThanOrEqual\": \"*\",\n \"status\": \"unaffected\",\n \"versionType\": \"original_commit_for_fix\"\n }\n ]\n }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","score":7.8,"severity":"HIGH"}],"references":["https://git.kernel.org/stable/c/8dbed691e43a50903658130bde0fcb5abc425b37","https://git.kernel.org/stable/c/9b40bdc2a3298225dffab8158208a0d8c6300578","https://git.kernel.org/stable/c/fd470f0a97b8e9a125f520265d2f3b088ffb5b8a","https://git.kernel.org/stable/c/ceafb893b12f23331dcc5ff9587e643c3a40ee9f","https://git.kernel.org/stable/c/2e0e74c59b2761a414d9f48d7bee1e45220b2427","https://git.kernel.org/stable/c/96a4713ae041cc85e712bac682cd2e644004d6c6","https://git.kernel.org/stable/c/474d6c771d798bca84f0a140b611e36743511e18","https://git.kernel.org/stable/c/98d0912e9f841e5529a5b89a972805f34cb1c69d"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-52943","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-52943","identifiers":["CVE-2026-52943"]},"retained":false,"historicalAffected":[]}],"coverage":[]}