{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2024-56635", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2024-12-27T15:00:39.838Z", "datePublished": "2024-12-27T15:02:38.213Z", "dateUpdated": "2026-08-05T11:45:36.867Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T11:45:36.867Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: avoid potential UAF in default_operstate()\n\nsyzbot reported an UAF in default_operstate() [1]\n\nIssue is a race between device and netns dismantles.\n\nAfter calling __rtnl_unlock() from netdev_run_todo(),\nwe can not assume the netns of each device is still alive.\n\nMake sure the device is not in NETREG_UNREGISTERED state,\nand add an ASSERT_RTNL() before the call to\n__dev_get_by_index().\n\nWe might move this ASSERT_RTNL() in __dev_get_by_index()\nin the future.\n\n[1]\n\nBUG: KASAN: slab-use-after-free in __dev_get_by_index+0x5d/0x110 net/core/dev.c:852\nRead of size 8 at addr ffff888043eba1b0 by task syz.0.0/5339\n\nCPU: 0 UID: 0 PID: 5339 Comm: syz.0.0 Not tainted 6.12.0-syzkaller-10296-gaaf20f870da0 #0\nHardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014\nCall Trace:\n \n __dump_stack lib/dump_stack.c:94 [inline]\n dump_stack_lvl+0x241/0x360 lib/dump_stack.c:120\n print_address_description mm/kasan/report.c:378 [inline]\n print_report+0x169/0x550 mm/kasan/report.c:489\n kasan_report+0x143/0x180 mm/kasan/report.c:602\n __dev_get_by_index+0x5d/0x110 net/core/dev.c:852\n default_operstate net/core/link_watch.c:51 [inline]\n rfc2863_policy+0x224/0x300 net/core/link_watch.c:67\n linkwatch_do_dev+0x3e/0x170 net/core/link_watch.c:170\n netdev_run_todo+0x461/0x1000 net/core/dev.c:10894\n rtnl_unlock net/core/rtnetlink.c:152 [inline]\n rtnl_net_unlock include/linux/rtnetlink.h:133 [inline]\n rtnl_dellink+0x760/0x8d0 net/core/rtnetlink.c:3520\n rtnetlink_rcv_msg+0x791/0xcf0 net/core/rtnetlink.c:6911\n netlink_rcv_skb+0x1e3/0x430 net/netlink/af_netlink.c:2541\n netlink_unicast_kernel net/netlink/af_netlink.c:1321 [inline]\n netlink_unicast+0x7f6/0x990 net/netlink/af_netlink.c:1347\n netlink_sendmsg+0x8e4/0xcb0 net/netlink/af_netlink.c:1891\n sock_sendmsg_nosec net/socket.c:711 [inline]\n __sock_sendmsg+0x221/0x270 net/socket.c:726\n ____sys_sendmsg+0x52a/0x7e0 net/socket.c:2583\n ___sys_sendmsg net/socket.c:2637 [inline]\n __sys_sendmsg+0x269/0x350 net/socket.c:2669\n do_syscall_x64 arch/x86/entry/common.c:52 [inline]\n do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83\n entry_SYSCALL_64_after_hwframe+0x77/0x7f\nRIP: 0033:0x7f2a3cb80809\nCode: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48\nRSP: 002b:00007f2a3d9cd058 EFLAGS: 00000246 ORIG_RAX: 000000000000002e\nRAX: ffffffffffffffda RBX: 00007f2a3cd45fa0 RCX: 00007f2a3cb80809\nRDX: 0000000000000000 RSI: 0000000020000000 RDI: 0000000000000008\nRBP: 00007f2a3cbf393e R08: 0000000000000000 R09: 0000000000000000\nR10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000\nR13: 0000000000000000 R14: 00007f2a3cd45fa0 R15: 00007ffd03bc65c8\n \n\nAllocated by task 5339:\n kasan_save_stack mm/kasan/common.c:47 [inline]\n kasan_save_track+0x3f/0x80 mm/kasan/common.c:68\n poison_kmalloc_redzone mm/kasan/common.c:377 [inline]\n __kasan_kmalloc+0x98/0xb0 mm/kasan/common.c:394\n kasan_kmalloc include/linux/kasan.h:260 [inline]\n __kmalloc_cache_noprof+0x243/0x390 mm/slub.c:4314\n kmalloc_noprof include/linux/slab.h:901 [inline]\n kmalloc_array_noprof include/linux/slab.h:945 [inline]\n netdev_create_hash net/core/dev.c:11870 [inline]\n netdev_init+0x10c/0x250 net/core/dev.c:11890\n ops_init+0x31e/0x590 net/core/net_namespace.c:138\n setup_net+0x287/0x9e0 net/core/net_namespace.c:362\n copy_net_ns+0x33f/0x570 net/core/net_namespace.c:500\n create_new_namespaces+0x425/0x7b0 kernel/nsproxy.c:110\n unshare_nsproxy_namespaces+0x124/0x180 kernel/nsproxy.c:228\n ksys_unshare+0x57d/0xa70 kernel/fork.c:3314\n __do_sys_unshare kernel/fork.c:3385 [inline]\n __se_sys_unshare kernel/fork.c:3383 [inline]\n __x64_sys_unshare+0x38/0x40 kernel/fork.c:3383\n do_syscall_x64 arch/x86/entry/common.c:52 [inline]\n do_syscall_64+0xf3/0x230 arch/x8\n---truncated---" } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "baseScore": 7.8, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:L - The vulnerability is reached through local syscalls only — `unshare(CLONE_NEWUSER|CLONE_NEWNET)` to create the namespace and an `RTM_DELLINK` rtnetlink message via `sendmsg()` on an `AF_NETLINK` socket. No network peer data is involved.\nAC:L - The attacker controls both sides of the race: they create and populate the netns, choose when to drop its last reference (triggering `cleanup_net`), and choose when to send RTM_DELLINK, and can retry the race in a loop indefinitely at no cost. syzbot reproduced it, and veth/vlan/macvlan satisfy the `iflink != ifindex` precondition in default configurations.\nPR:L - An unprivileged local user gets CAP_NET_ADMIN inside a new network namespace via `unshare -Urn`, which is exactly the path in the syzbot allocation trace (`ksys_unshare` → `copy_net_ns`), and that is sufficient to create veth devices and issue RTM_DELLINK.\nUI:N - The attacker performs all steps itself — namespace creation, device creation, link deletion, and namespace teardown — with no action required from any other user.\nS:U - The use-after-free occurs in kernel memory and its impact stays within the kernel's own security authority; no VM, IOMMU, or hypervisor boundary is crossed.\nC:H - This is a slab use-after-free read of a freed `kmalloc-2k` hash array whose contents the attacker can control via heap spray, turning the `hlist_for_each_entry()` walk into a controlled-pointer dereference; the resulting carrier bit is reflected into `dev->operstate` and read back over netlink, yielding a kernel memory disclosure oracle.\nI:H - A use-after-free on a heavily reused general-purpose slab cache gives the attacker influence over the freed object contents and over which pointer the kernel follows and stores as `peer`, which is the standard basis for escalating to control-flow/state corruption.\nA:H - KASAN confirms a slab-use-after-free read, and walking the stale hash bucket dereferences reused or garbage pointers, causing a kernel oops or panic; the race can be retried repeatedly to force a crash." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/core/link_watch.c" ], "versions": [ { "version": "8c55facecd7ade835287298ce325f930d888d8ec", "lessThan": "3265aab0736f78bb218200b06b1abb525c316269", "status": "affected", "versionType": "git" }, { "version": "8c55facecd7ade835287298ce325f930d888d8ec", "lessThan": "316183d58319f191e16503bc2dffa156c4442df2", "status": "affected", "versionType": "git" }, { "version": "8c55facecd7ade835287298ce325f930d888d8ec", "lessThan": "750e51603395e755537da08f745864c93e3ce741", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/core/link_watch.c" ], "versions": [ { "version": "6.2", "status": "affected" }, { "version": "0", "lessThan": "6.2", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.66", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.5", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.13", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.2", "versionEndExcluding": "6.6.66" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.2", "versionEndExcluding": "6.12.5" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.2", "versionEndExcluding": "6.13" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/3265aab0736f78bb218200b06b1abb525c316269" }, { "url": "https://git.kernel.org/stable/c/316183d58319f191e16503bc2dffa156c4442df2" }, { "url": "https://git.kernel.org/stable/c/750e51603395e755537da08f745864c93e3ce741" } ], "title": "net: avoid potential UAF in default_operstate()", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "metrics": [ { "cvssV3_1": { "scope": "UNCHANGED", "version": "3.1", "baseScore": 7.8, "attackVector": "LOCAL", "baseSeverity": "HIGH", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H", "integrityImpact": "HIGH", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "HIGH", "privilegesRequired": "LOW", "confidentialityImpact": "HIGH" } }, { "other": { "type": "ssvc", "content": { "id": "CVE-2024-56635", "role": "CISA Coordinator", "options": [ { "Exploitation": "none" }, { "Automatable": "no" }, { "Technical Impact": "total" } ], "version": "2.0.3", "timestamp": "2025-02-10T17:12:40.278798Z" } } } ], "problemTypes": [ { "descriptions": [ { "lang": "en", "type": "CWE", "cweId": "CWE-416", "description": "CWE-416 Use After Free" } ] } ], "title": "CISA ADP Vulnrichment", "providerMetadata": { "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2025-02-10T17:21:08.285Z" } } ] } }