{"id":"CVE-2024-56646","summary":"ipv6: avoid possible NULL deref in modify_prefix_route()","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nipv6: avoid possible NULL deref in modify_prefix_route()\n\nsyzbot found a NULL deref [1] in modify_prefix_route(), caused by one\nfib6_info without a fib6_table pointer set.\n\nThis can happen for net-\u003eipv6.fib6_null_entry\n\n[1]\nOops: general protection fault, probably for non-canonical address 0xdffffc0000000006: 0000 [#1] PREEMPT SMP KASAN NOPTI\nKASAN: null-ptr-deref in range [0x0000000000000030-0x0000000000000037]\nCPU: 1 UID: 0 PID: 5837 Comm: syz-executor888 Not tainted 6.12.0-syzkaller-09567-g7eef7e306d3c #0\nHardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024\n RIP: 0010:__lock_acquire+0xe4/0x3c40 kernel/locking/lockdep.c:5089\nCode: 08 84 d2 0f 85 15 14 00 00 44 8b 0d ca 98 f5 0e 45 85 c9 0f 84 b4 0e 00 00 48 b8 00 00 00 00 00 fc ff df 4c 89 e2 48 c1 ea 03 \u003c80\u003e 3c 02 00 0f 85 96 2c 00 00 49 8b 04 24 48 3d a0 07 7f 93 0f 84\nRSP: 0018:ffffc900035d7268 EFLAGS: 00010006\nRAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000\nRDX: 0000000000000006 RSI: 1ffff920006bae5f RDI: 0000000000000030\nRBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000001\nR10: ffffffff90608e17 R11: 0000000000000001 R12: 0000000000000030\nR13: ffff888036334880 R14: 0000000000000000 R15: 0000000000000000\nFS:  0000555579e90380(0000) GS:ffff8880b8700000(0000) knlGS:0000000000000000\nCS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\nCR2: 00007ffc59cc4278 CR3: 0000000072b54000 CR4: 00000000003526f0\nDR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000\nDR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400\nCall Trace:\n \u003cTASK\u003e\n  lock_acquire.part.0+0x11b/0x380 kernel/locking/lockdep.c:5849\n  __raw_spin_lock_bh include/linux/spinlock_api_smp.h:126 [inline]\n  _raw_spin_lock_bh+0x33/0x40 kernel/locking/spinlock.c:178\n  spin_lock_bh include/linux/spinlock.h:356 [inline]\n  modify_prefix_route+0x30b/0x8b0 net/ipv6/addrconf.c:4831\n  inet6_addr_modify net/ipv6/addrconf.c:4923 [inline]\n  inet6_rtm_newaddr+0x12c7/0x1ab0 net/ipv6/addrconf.c:5055\n  rtnetlink_rcv_msg+0x3c7/0xea0 net/core/rtnetlink.c:6920\n  netlink_rcv_skb+0x16b/0x440 net/netlink/af_netlink.c:2541\n  netlink_unicast_kernel net/netlink/af_netlink.c:1321 [inline]\n  netlink_unicast+0x53c/0x7f0 net/netlink/af_netlink.c:1347\n  netlink_sendmsg+0x8b8/0xd70 net/netlink/af_netlink.c:1891\n  sock_sendmsg_nosec net/socket.c:711 [inline]\n  __sock_sendmsg net/socket.c:726 [inline]\n  ____sys_sendmsg+0xaaf/0xc90 net/socket.c:2583\n  ___sys_sendmsg+0x135/0x1e0 net/socket.c:2637\n  __sys_sendmsg+0x16e/0x220 net/socket.c:2669\n  do_syscall_x64 arch/x86/entry/common.c:52 [inline]\n  do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83\n entry_SYSCALL_64_after_hwframe+0x77/0x7f\nRIP: 0033:0x7fd1dcef8b79\nCode: 28 00 00 00 75 05 48 83 c4 28 c3 e8 c1 17 00 00 90 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 \u003c48\u003e 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48\nRSP: 002b:00007ffc59cc4378 EFLAGS: 00000246 ORIG_RAX: 000000000000002e\nRAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fd1dcef8b79\nRDX: 0000000000040040 RSI: 0000000020000140 RDI: 0000000000000004\nRBP: 00000000000113fd R08: 0000000000000006 R09: 0000000000000006\nR10: 0000000000000006 R11: 0000000000000246 R12: 00007ffc59cc438c\nR13: 431bde82d7b634db R14: 0000000000000001 R15: 0000000000000001\n \u003c/TASK\u003e","modified":"2026-03-20T12:40:55.757909Z","published":"2024-12-27T15:02:47.265Z","related":["USN-7379-2","USN-7380-1"],"database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2024/56xxx/CVE-2024-56646.json","cna_assigner":"Linux"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/01f95357e47219a9c4b29e177b717edbfab721b4"},{"type":"WEB","url":"https://git.kernel.org/stable/c/90f7d995b861fd77ae4885cc58e26a6a4e5ccdb9"},{"type":"WEB","url":"https://git.kernel.org/stable/c/a747e02430dfb3657141f99aa6b09331283fa493"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2024/56xxx/CVE-2024-56646.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2024-56646"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"bd12abe294c7738421bdfbc486f1909d02db30e9"},{"fixed":"90f7d995b861fd77ae4885cc58e26a6a4e5ccdb9"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"5eb902b8e7193cdcb33242af0a56502e6b5206e9"},{"fixed":"01f95357e47219a9c4b29e177b717edbfab721b4"},{"fixed":"a747e02430dfb3657141f99aa6b09331283fa493"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2024-56646.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H"}]}