{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2024-41041", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2024-07-12T12:17:45.623Z", "datePublished": "2024-07-29T14:31:54.647Z", "dateUpdated": "2026-08-05T11:34:56.026Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T11:34:56.026Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nudp: Set SOCK_RCU_FREE earlier in udp_lib_get_port().\n\nsyzkaller triggered the warning [0] in udp_v4_early_demux().\n\nIn udp_v[46]_early_demux() and sk_lookup(), we do not touch the refcount\nof the looked-up sk and use sock_pfree() as skb->destructor, so we check\nSOCK_RCU_FREE to ensure that the sk is safe to access during the RCU grace\nperiod.\n\nCurrently, SOCK_RCU_FREE is flagged for a bound socket after being put\ninto the hash table. Moreover, the SOCK_RCU_FREE check is done too early\nin udp_v[46]_early_demux() and sk_lookup(), so there could be a small race\nwindow:\n\n CPU1 CPU2\n ---- ----\n udp_v4_early_demux() udp_lib_get_port()\n | |- hlist_add_head_rcu()\n |- sk = __udp4_lib_demux_lookup() |\n |- DEBUG_NET_WARN_ON_ONCE(sk_is_refcounted(sk));\n `- sock_set_flag(sk, SOCK_RCU_FREE)\n\nWe had the same bug in TCP and fixed it in commit 871019b22d1b (\"net:\nset SOCK_RCU_FREE before inserting socket into hashtable\").\n\nLet's apply the same fix for UDP.\n\n[0]:\nWARNING: CPU: 0 PID: 11198 at net/ipv4/udp.c:2599 udp_v4_early_demux+0x481/0xb70 net/ipv4/udp.c:2599\nModules linked in:\nCPU: 0 PID: 11198 Comm: syz-executor.1 Not tainted 6.9.0-g93bda33046e7 #13\nHardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014\nRIP: 0010:udp_v4_early_demux+0x481/0xb70 net/ipv4/udp.c:2599\nCode: c5 7a 15 fe bb 01 00 00 00 44 89 e9 31 ff d3 e3 81 e3 bf ef ff ff 89 de e8 2c 74 15 fe 85 db 0f 85 02 06 00 00 e8 9f 7a 15 fe <0f> 0b e8 98 7a 15 fe 49 8d 7e 60 e8 4f 39 2f fe 49 c7 46 60 20 52\nRSP: 0018:ffffc9000ce3fa58 EFLAGS: 00010293\nRAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff8318c92c\nRDX: ffff888036ccde00 RSI: ffffffff8318c2f1 RDI: 0000000000000001\nRBP: ffff88805a2dd6e0 R08: 0000000000000001 R09: 0000000000000000\nR10: 0000000000000000 R11: 0001ffffffffffff R12: ffff88805a2dd680\nR13: 0000000000000007 R14: ffff88800923f900 R15: ffff88805456004e\nFS: 00007fc449127640(0000) GS:ffff88807dc00000(0000) knlGS:0000000000000000\nCS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033\nCR2: 00007fc449126e38 CR3: 000000003de4b002 CR4: 0000000000770ef0\nDR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000\nDR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600\nPKRU: 55555554\nCall Trace:\n \n ip_rcv_finish_core.constprop.0+0xbdd/0xd20 net/ipv4/ip_input.c:349\n ip_rcv_finish+0xda/0x150 net/ipv4/ip_input.c:447\n NF_HOOK include/linux/netfilter.h:314 [inline]\n NF_HOOK include/linux/netfilter.h:308 [inline]\n ip_rcv+0x16c/0x180 net/ipv4/ip_input.c:569\n __netif_receive_skb_one_core+0xb3/0xe0 net/core/dev.c:5624\n __netif_receive_skb+0x21/0xd0 net/core/dev.c:5738\n netif_receive_skb_internal net/core/dev.c:5824 [inline]\n netif_receive_skb+0x271/0x300 net/core/dev.c:5884\n tun_rx_batched drivers/net/tun.c:1549 [inline]\n tun_get_user+0x24db/0x2c50 drivers/net/tun.c:2002\n tun_chr_write_iter+0x107/0x1a0 drivers/net/tun.c:2048\n new_sync_write fs/read_write.c:497 [inline]\n vfs_write+0x76f/0x8d0 fs/read_write.c:590\n ksys_write+0xbf/0x190 fs/read_write.c:643\n __do_sys_write fs/read_write.c:655 [inline]\n __se_sys_write fs/read_write.c:652 [inline]\n __x64_sys_write+0x41/0x50 fs/read_write.c:652\n x64_sys_call+0xe66/0x1990 arch/x86/include/generated/asm/syscalls_64.h:2\n do_syscall_x64 arch/x86/entry/common.c:52 [inline]\n do_syscall_64+0x4b/0x110 arch/x86/entry/common.c:83\n entry_SYSCALL_64_after_hwframe+0x4b/0x53\nRIP: 0033:0x7fc44a68bc1f\nCode: 89 54 24 18 48 89 74 24 10 89 7c 24 08 e8 e9 cf f5 ff 48 8b 54 24 18 48 8b 74 24 10 41 89 c0 8b 7c 24 08 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 31 44 89 c7 48 89 44 24 08 e8 3c d0 f5 ff 48\nRSP: 002b:00007fc449126c90 EFLAGS: 00000293 ORIG_RAX: 0000000000000001\nRAX: ffffffffffffffda RBX: 00000000004bc050 RCX: 00007fc44a68bc1f\nR\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 racing writer side is `udp_lib_get_port()`, reached only through a local `bind()`/`connect()` syscall on a UDP socket, and the reader side needs a packet on a dst-less receive path (tun/veth), which the attacker creates locally in their own netns. A remote peer sending UDP packets cannot by itself put a socket into the unflagged window, so the bug is not remotely reachable.\nAC:L - The attacker owns both halves of the race — a thread loop calling `bind()`/`connect()` on UDP sockets and a concurrent injector feeding matching packets through tun/veth — and can widen the window by contending `hslot2->lock` and by running massively in parallel across CPUs. Per the race guidance, an attacker-created race is Low complexity.\nPR:L - Binding UDP sockets requires no privilege at all, and the packet-injection side (tun/veth creation) is obtained by any unprivileged user via `unshare -Urn`, where CAP_NET_ADMIN is granted in the new user namespace. No real root or init-namespace capability is needed.\nUI:N - The attacker performs every step — socket binding, device setup, and packet injection — with no action required from any other user or administrator.\nS:U - The refcount underflow, use-after-free, and any resulting panic all occur in the kernel of the same host under the same security authority; no VM, IOMMU, or sandbox boundary is crossed.\nC:H - `skb_steal_sock()` reading a stale-clear `SOCK_RCU_FREE` yields `refcounted == true`, so `udp_rcv()` drops a reference it never took, freeing `struct udp_sock` while the owning fd and the hash tables still point at it. The resulting use-after-free lets an attacker refill the slab and read back kernel memory through subsequent socket operations.\nI:H - The same unbalanced `sock_put()` produces a use-after-free on a socket object containing function pointers (`sk_prot`, `sk_data_ready`, `sk_destruct`) and list heads, which is a classic heap-spray target giving arbitrary-write and control-flow-hijack primitives.\nA:H - The race trips `DEBUG_NET_WARN_ON_ONCE()` in `udp_v4_early_demux()` and the unconditional `WARN_ONCE(1, \"Found non-RCU, unreferenced socket!\")` in `sk_lookup()`, tainting the kernel and panicking outright on `panic_on_warn=1` systems; the premature socket free additionally corrupts the UDP hash lists and crashes the kernel even when not exploited further." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "net/ipv4/udp.c" ], "versions": [ { "version": "6acc9b432e6714d72d7d77ec7c27f6f8358d0c71", "lessThan": "7a67c4e47626e6daccda62888f8b096abb5d3940", "status": "affected", "versionType": "git" }, { "version": "6acc9b432e6714d72d7d77ec7c27f6f8358d0c71", "lessThan": "9f965684c57c3117cfd2f754dd3270383c529fba", "status": "affected", "versionType": "git" }, { "version": "6acc9b432e6714d72d7d77ec7c27f6f8358d0c71", "lessThan": "ddf516e50bf8a7bc9b3bd8a9831f9c7a8131a32a", "status": "affected", "versionType": "git" }, { "version": "6acc9b432e6714d72d7d77ec7c27f6f8358d0c71", "lessThan": "a6db0d3ea6536e7120871e5448b3032570152ec6", "status": "affected", "versionType": "git" }, { "version": "6acc9b432e6714d72d7d77ec7c27f6f8358d0c71", "lessThan": "c5fd77ca13d657c6e99bf04f0917445e6a80231e", "status": "affected", "versionType": "git" }, { "version": "6acc9b432e6714d72d7d77ec7c27f6f8358d0c71", "lessThan": "20ceae10623c3b29fdf7609690849475bcdebdb0", "status": "affected", "versionType": "git" }, { "version": "6acc9b432e6714d72d7d77ec7c27f6f8358d0c71", "lessThan": "5c0b485a8c6116516f33925b9ce5b6104a6eadfd", "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/ipv4/udp.c" ], "versions": [ { "version": "4.20", "status": "affected" }, { "version": "0", "lessThan": "4.20", "status": "unaffected", "versionType": "semver" }, { "version": "5.4.280", "lessThanOrEqual": "5.4.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.222", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.163", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.100", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.41", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.9.10", "lessThanOrEqual": "6.9.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.10", "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": "4.20", "versionEndExcluding": "5.4.280" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.20", "versionEndExcluding": "5.10.222" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.20", "versionEndExcluding": "5.15.163" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.20", "versionEndExcluding": "6.1.100" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.20", "versionEndExcluding": "6.6.41" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.20", "versionEndExcluding": "6.9.10" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.20", "versionEndExcluding": "6.10" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/7a67c4e47626e6daccda62888f8b096abb5d3940" }, { "url": "https://git.kernel.org/stable/c/9f965684c57c3117cfd2f754dd3270383c529fba" }, { "url": "https://git.kernel.org/stable/c/ddf516e50bf8a7bc9b3bd8a9831f9c7a8131a32a" }, { "url": "https://git.kernel.org/stable/c/a6db0d3ea6536e7120871e5448b3032570152ec6" }, { "url": "https://git.kernel.org/stable/c/c5fd77ca13d657c6e99bf04f0917445e6a80231e" }, { "url": "https://git.kernel.org/stable/c/20ceae10623c3b29fdf7609690849475bcdebdb0" }, { "url": "https://git.kernel.org/stable/c/5c0b485a8c6116516f33925b9ce5b6104a6eadfd" } ], "title": "udp: Set SOCK_RCU_FREE earlier in udp_lib_get_port().", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "title": "CVE Program Container", "references": [ { "url": "https://git.kernel.org/stable/c/7a67c4e47626e6daccda62888f8b096abb5d3940", "tags": [ "x_transferred" ] }, { "url": "https://git.kernel.org/stable/c/9f965684c57c3117cfd2f754dd3270383c529fba", "tags": [ "x_transferred" ] }, { "url": "https://git.kernel.org/stable/c/ddf516e50bf8a7bc9b3bd8a9831f9c7a8131a32a", "tags": [ "x_transferred" ] }, { "url": "https://git.kernel.org/stable/c/a6db0d3ea6536e7120871e5448b3032570152ec6", "tags": [ "x_transferred" ] }, { "url": "https://git.kernel.org/stable/c/c5fd77ca13d657c6e99bf04f0917445e6a80231e", "tags": [ "x_transferred" ] }, { "url": "https://git.kernel.org/stable/c/20ceae10623c3b29fdf7609690849475bcdebdb0", "tags": [ "x_transferred" ] }, { "url": "https://git.kernel.org/stable/c/5c0b485a8c6116516f33925b9ce5b6104a6eadfd", "tags": [ "x_transferred" ] }, { "url": "https://lists.debian.org/debian-lts-announce/2025/01/msg00001.html" } ], "providerMetadata": { "orgId": "af854a3a-2127-422b-91ae-364da2661108", "shortName": "CVE", "dateUpdated": "2025-11-03T21:59:39.558Z" } }, { "metrics": [ { "other": { "type": "ssvc", "content": { "id": "CVE-2024-41041", "role": "CISA Coordinator", "options": [ { "Exploitation": "none" }, { "Automatable": "no" }, { "Technical Impact": "partial" } ], "version": "2.0.3", "timestamp": "2024-09-10T16:23:13.757861Z" } } } ], "title": "CISA ADP Vulnrichment", "providerMetadata": { "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2024-09-11T17:32:58.050Z" } } ] } }