CVE ID:	CVE-2024-35969
Description:	In the Linux kernel, the following vulnerability has been resolved: ipv6: fix race condition between ipv6_get_ifaddr and ipv6_del_addr Although ipv6_get_ifaddr walks inet6_addr_lst under the RCU lock, it still means hlist_for_each_entry_rcu can return an item that got removed from the list. The memory itself of such item is not freed thanks to RCU but nothing guarantees the actual content of the memory is sane. In particular, the reference count can be zero. This can happen if ipv6_del_addr is called in parallel. ipv6_del_addr removes the entry from inet6_addr_lst (hlist_del_init_rcu(&ifp->addr_lst)) and drops all references (__in6_ifa_put(ifp) + in6_ifa_put(ifp)). With bad enough timing, this can happen: 1. In ipv6_get_ifaddr, hlist_for_each_entry_rcu returns an entry. 2. Then, the whole ipv6_del_addr is executed for the given entry. The reference count drops to zero and kfree_rcu is scheduled. 3. ipv6_get_ifaddr continues and tries to increments the reference count (in6_ifa_hold). 4. The rcu is unlocked and the entry is freed. 5. The freed entry is returned. Prevent increasing of the reference count in such case. The name in6_ifa_hold_safe is chosen to mimic the existing fib6_info_hold_safe. [ 41.506330] refcount_t: addition on 0; use-after-free. [ 41.506760] WARNING: CPU: 0 PID: 595 at lib/refcount.c:25 refcount_warn_saturate+0xa5/0x130 [ 41.507413] Modules linked in: veth bridge stp llc [ 41.507821] CPU: 0 PID: 595 Comm: python3 Not tainted 6.9.0-rc2.main-00208-g49563be82afa #14 [ 41.508479] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996) [ 41.509163] RIP: 0010:refcount_warn_saturate+0xa5/0x130 [ 41.509586] Code: ad ff 90 0f 0b 90 90 c3 cc cc cc cc 80 3d c0 30 ad 01 00 75 a0 c6 05 b7 30 ad 01 01 90 48 c7 c7 38 cc 7a 8c e8 cc 18 ad ff 90 <0f> 0b 90 90 c3 cc cc cc cc 80 3d 98 30 ad 01 00 0f 85 75 ff ff ff [ 41.510956] RSP: 0018:ffffbda3c026baf0 EFLAGS: 00010282 [ 41.511368] RAX: 0000000000000000 RBX: ffff9e9c46914800 RCX: 0000000000000000 [ 41.511910] RDX: ffff9e9c7ec29c00 RSI: ffff9e9c7ec1c900 RDI: ffff9e9c7ec1c900 [ 41.512445] RBP: ffff9e9c43660c9c R08: 0000000000009ffb R09: 00000000ffffdfff [ 41.512998] R10: 00000000ffffdfff R11: ffffffff8ca58a40 R12: ffff9e9c4339a000 [ 41.513534] R13: 0000000000000001 R14: ffff9e9c438a0000 R15: ffffbda3c026bb48 [ 41.514086] FS: 00007fbc4cda1740(0000) GS:ffff9e9c7ec00000(0000) knlGS:0000000000000000 [ 41.514726] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 41.515176] CR2: 000056233b337d88 CR3: 000000000376e006 CR4: 0000000000370ef0 [ 41.515713] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 41.516252] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 41.516799] Call Trace: [ 41.517037] [ 41.517249] ? __warn+0x7b/0x120 [ 41.517535] ? refcount_warn_saturate+0xa5/0x130 [ 41.517923] ? report_bug+0x164/0x190 [ 41.518240] ? handle_bug+0x3d/0x70 [ 41.518541] ? exc_invalid_op+0x17/0x70 [ 41.520972] ? asm_exc_invalid_op+0x1a/0x20 [ 41.521325] ? refcount_warn_saturate+0xa5/0x130 [ 41.521708] ipv6_get_ifaddr+0xda/0xe0 [ 41.522035] inet6_rtm_getaddr+0x342/0x3f0 [ 41.522376] ? __pfx_inet6_rtm_getaddr+0x10/0x10 [ 41.522758] rtnetlink_rcv_msg+0x334/0x3d0 [ 41.523102] ? netlink_unicast+0x30f/0x390 [ 41.523445] ? __pfx_rtnetlink_rcv_msg+0x10/0x10 [ 41.523832] netlink_rcv_skb+0x53/0x100 [ 41.524157] netlink_unicast+0x23b/0x390 [ 41.524484] netlink_sendmsg+0x1f2/0x440 [ 41.524826] __sys_sendto+0x1d8/0x1f0 [ 41.525145] __x64_sys_sendto+0x1f/0x30 [ 41.525467] do_syscall_64+0xa5/0x1b0 [ 41.525794] entry_SYSCALL_64_after_hwframe+0x72/0x7a [ 41.526213] RIP: 0033:0x7fbc4cfcea9a [ 41.526528] Code: d8 64 89 02 48 c7 c0 ff ff ff ff eb b8 0f 1f 00 f3 0f 1e fa 41 89 ca 64 8b 04 25 18 00 00 00 85 c0 75 15 b8 2c 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 7e c3 0f 1f 44 00 00 41 54 48 83 ec 30 44 89 [ 41.527942] RSP: 002b:00007f ---truncated---
Test IDs:	None available
Cross References:	Common Vulnerability Exposure (CVE) ID: CVE-2024-35969 https://git.kernel.org/stable/c/01b11a0566670612bd464a932e5ac2eae53d8652 https://git.kernel.org/stable/c/01b11a0566670612bd464a932e5ac2eae53d8652 https://git.kernel.org/stable/c/3fb02ec57ead2891a2306af8c51a306bc5945e70 https://git.kernel.org/stable/c/3fb02ec57ead2891a2306af8c51a306bc5945e70 https://git.kernel.org/stable/c/4b19e9507c275de0cfe61c24db69179dc52cf9fb https://git.kernel.org/stable/c/4b19e9507c275de0cfe61c24db69179dc52cf9fb https://git.kernel.org/stable/c/6cdb20c342cd0193d3e956e3d83981d0f438bb83 https://git.kernel.org/stable/c/6cdb20c342cd0193d3e956e3d83981d0f438bb83 https://git.kernel.org/stable/c/7633c4da919ad51164acbf1aa322cc1a3ead6129 https://git.kernel.org/stable/c/7633c4da919ad51164acbf1aa322cc1a3ead6129 https://git.kernel.org/stable/c/b4b3b69a19016d4e7fbdbd1dbcc184915eb862e1 https://git.kernel.org/stable/c/b4b3b69a19016d4e7fbdbd1dbcc184915eb862e1 https://git.kernel.org/stable/c/cca606e14264098cba65efa82790825dbf69e903 https://git.kernel.org/stable/c/cca606e14264098cba65efa82790825dbf69e903 https://git.kernel.org/stable/c/de76ae9ea1a6cf9e77fcec4f2df2904e26c23ceb https://git.kernel.org/stable/c/de76ae9ea1a6cf9e77fcec4f2df2904e26c23ceb