{"id":"CVE-2024-41041","url":"https://www.cyber-defence.io/tools/cve/CVE-2024-41041","generatedAt":"2026-10-28T01:14:23.066Z","title":"In the Linux kernel, the following vulnerability has been resolved: udp: Set SOCK_RCU_FREE earlier in udp_lib_get_port(). syzkaller triggered the warning [0] in udp_v4_early_demux().","description":"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 <TASK>\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---","published":"2024-07-29T15:15:13.000Z","lastModified":"2026-08-04T11:19:22.000Z","status":"Modified","sourceIdentifier":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","cvss":{"version":"3.1","score":5.5,"severity":"MEDIUM","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"},"cwe":[],"affected":["linux/linux kernel"],"epss":{"score":0.00292,"percentile":0.2153,"date":"2026-10-26","history":[]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"low","text":"Lower severity and a low EPSS score (0.29%). Track it; it rarely justifies an emergency change on its own."},"changes":[],"references":[{"url":"https://git.kernel.org/stable/c/20ceae10623c3b29fdf7609690849475bcdebdb0","tags":["Patch"],"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/5c0b485a8c6116516f33925b9ce5b6104a6eadfd","tags":["Patch"],"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/7a67c4e47626e6daccda62888f8b096abb5d3940","tags":["Patch"],"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/9f965684c57c3117cfd2f754dd3270383c529fba","tags":["Patch"],"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/a6db0d3ea6536e7120871e5448b3032570152ec6","tags":["Patch"],"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/c5fd77ca13d657c6e99bf04f0917445e6a80231e","tags":["Patch"],"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/ddf516e50bf8a7bc9b3bd8a9831f9c7a8131a32a","tags":["Patch"],"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/20ceae10623c3b29fdf7609690849475bcdebdb0","tags":["Patch"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://git.kernel.org/stable/c/5c0b485a8c6116516f33925b9ce5b6104a6eadfd","tags":["Patch"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://git.kernel.org/stable/c/7a67c4e47626e6daccda62888f8b096abb5d3940","tags":["Patch"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://git.kernel.org/stable/c/9f965684c57c3117cfd2f754dd3270383c529fba","tags":["Patch"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://git.kernel.org/stable/c/a6db0d3ea6536e7120871e5448b3032570152ec6","tags":["Patch"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://git.kernel.org/stable/c/c5fd77ca13d657c6e99bf04f0917445e6a80231e","tags":["Patch"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://git.kernel.org/stable/c/ddf516e50bf8a7bc9b3bd8a9831f9c7a8131a32a","tags":["Patch"],"source":"af854a3a-2127-422b-91ae-364da2661108"},{"url":"https://lists.debian.org/debian-lts-announce/2025/01/msg00001.html","source":"af854a3a-2127-422b-91ae-364da2661108"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2024-41041","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}