{"cve":"CVE-2021-47238","nvd":{"published":"2024-05-21T15:15:13.017","modified":"2026-06-17T04:16:58.900","status":"Analyzed","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: ipv4: fix memory leak in ip_mc_add1_src\n\nBUG: memory leak\nunreferenced object 0xffff888101bc4c00 (size 32):\n  comm \"syz-executor527\", pid 360, jiffies 4294807421 (age 19.329s)\n  hex dump (first 32 bytes):\n    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................\n    01 00 00 00 00 00 00 00 ac 14 14 bb 00 00 02 00 ................\n  backtrace:\n    [<00000000f17c5244>] kmalloc include/linux/slab.h:558 [inline]\n    [<00000000f17c5244>] kzalloc include/linux/slab.h:688 [inline]\n    [<00000000f17c5244>] ip_mc_add1_src net/ipv4/igmp.c:1971 [inline]\n    [<00000000f17c5244>] ip_mc_add_src+0x95f/0xdb0 net/ipv4/igmp.c:2095\n    [<000000001cb99709>] ip_mc_source+0x84c/0xea0 net/ipv4/igmp.c:2416\n    [<0000000052cf19ed>] do_ip_setsockopt net/ipv4/ip_sockglue.c:1294 [inline]\n    [<0000000052cf19ed>] ip_setsockopt+0x114b/0x30c0 net/ipv4/ip_sockglue.c:1423\n    [<00000000477edfbc>] raw_setsockopt+0x13d/0x170 net/ipv4/raw.c:857\n    [<00000000e75ca9bb>] __sys_setsockopt+0x158/0x270 net/socket.c:2117\n    [<00000000bdb993a8>] __do_sys_setsockopt net/socket.c:2128 [inline]\n    [<00000000bdb993a8>] __se_sys_setsockopt net/socket.c:2125 [inline]\n    [<00000000bdb993a8>] __x64_sys_setsockopt+0xba/0x150 net/socket.c:2125\n    [<000000006a1ffdbd>] do_syscall_64+0x40/0x80 arch/x86/entry/common.c:47\n    [<00000000b11467c4>] entry_SYSCALL_64_after_hwframe+0x44/0xae\n\nIn commit 24803f38a5c0 (\"igmp: do not remove igmp souce list info when set\nlink down\"), the ip_mc_clear_src() in ip_mc_destroy_dev() was removed,\nbecause it was also called in igmpv3_clear_delrec().\n\nRough callgraph:\n\ninetdev_destroy\n-> ip_mc_destroy_dev\n     -> igmpv3_clear_delrec\n        -> ip_mc_clear_src\n-> RCU_INIT_POINTER(dev->ip_ptr, NULL)\n\nHowever, ip_mc_clear_src() called in igmpv3_clear_delrec() doesn't\nrelease in_dev->mc_list->sources. And RCU_INIT_POINTER() assigns the\nNULL to dev->ip_ptr. As a result, in_dev cannot be obtained through\ninetdev_by_index() and then in_dev->mc_list->sources cannot be released\nby ip_mc_del1_src() in the sock_close. Rough call sequence goes like:\n\nsock_close\n-> __sock_release\n   -> inet_release\n      -> ip_mc_drop_socket\n         -> inetdev_by_index\n         -> ip_mc_leave_src\n            -> ip_mc_del_src\n               -> ip_mc_del1_src\n\nSo we still need to call ip_mc_clear_src() in ip_mc_destroy_dev() to free\nin_dev->mc_list->sources.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","score":5.5},"cwes":["CWE-400"],"references":["https://git.kernel.org/stable/c/0dc13e75507faa17ac9f7562b4ef7bf8fcd78422","https://git.kernel.org/stable/c/1e28018b5c83d5073f74a6fb72eabe8370b2f501","https://git.kernel.org/stable/c/3dd2aeac2e9624cff9fa634710837e4f2e352758","https://git.kernel.org/stable/c/6cff57eea3347f79f1867cc53e1093b6614138d8","https://git.kernel.org/stable/c/77de6ee73f54a9a89c0afa0bf4c53b239aa9953a"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-19T21:50:30.954589733+00:00"},"epss":{"cve":"CVE-2021-47238","score":0.00236,"percentile":0.14682,"date":"2026-10-31"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}