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Message-ID: <2024031512-CVE-2021-47126-f717@gregkh> Date: Fri, 15 Mar 2024 21:15:16 +0100 From: Greg Kroah-Hartman <gregkh@...uxfoundation.org> To: linux-cve-announce@...r.kernel.org Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org> Subject: CVE-2021-47126: ipv6: Fix KASAN: slab-out-of-bounds Read in fib6_nh_flush_exceptions Description =========== In the Linux kernel, the following vulnerability has been resolved: ipv6: Fix KASAN: slab-out-of-bounds Read in fib6_nh_flush_exceptions Reported by syzbot: HEAD commit: 90c911ad Merge tag 'fixes' of git://git.kernel.org/pub/scm.. git tree: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master dashboard link: https://syzkaller.appspot.com/bug?extid=123aa35098fd3c000eb7 compiler: Debian clang version 11.0.1-2 ================================================================== BUG: KASAN: slab-out-of-bounds in fib6_nh_get_excptn_bucket net/ipv6/route.c:1604 [inline] BUG: KASAN: slab-out-of-bounds in fib6_nh_flush_exceptions+0xbd/0x360 net/ipv6/route.c:1732 Read of size 8 at addr ffff8880145c78f8 by task syz-executor.4/17760 CPU: 0 PID: 17760 Comm: syz-executor.4 Not tainted 5.12.0-rc8-syzkaller #0 Call Trace: <IRQ> __dump_stack lib/dump_stack.c:79 [inline] dump_stack+0x202/0x31e lib/dump_stack.c:120 print_address_description+0x5f/0x3b0 mm/kasan/report.c:232 __kasan_report mm/kasan/report.c:399 [inline] kasan_report+0x15c/0x200 mm/kasan/report.c:416 fib6_nh_get_excptn_bucket net/ipv6/route.c:1604 [inline] fib6_nh_flush_exceptions+0xbd/0x360 net/ipv6/route.c:1732 fib6_nh_release+0x9a/0x430 net/ipv6/route.c:3536 fib6_info_destroy_rcu+0xcb/0x1c0 net/ipv6/ip6_fib.c:174 rcu_do_batch kernel/rcu/tree.c:2559 [inline] rcu_core+0x8f6/0x1450 kernel/rcu/tree.c:2794 __do_softirq+0x372/0x7a6 kernel/softirq.c:345 invoke_softirq kernel/softirq.c:221 [inline] __irq_exit_rcu+0x22c/0x260 kernel/softirq.c:422 irq_exit_rcu+0x5/0x20 kernel/softirq.c:434 sysvec_apic_timer_interrupt+0x91/0xb0 arch/x86/kernel/apic/apic.c:1100 </IRQ> asm_sysvec_apic_timer_interrupt+0x12/0x20 arch/x86/include/asm/idtentry.h:632 RIP: 0010:lock_acquire+0x1f6/0x720 kernel/locking/lockdep.c:5515 Code: f6 84 24 a1 00 00 00 02 0f 85 8d 02 00 00 f7 c3 00 02 00 00 49 bd 00 00 00 00 00 fc ff df 74 01 fb 48 c7 44 24 40 0e 36 e0 45 <4b> c7 44 3d 00 00 00 00 00 4b c7 44 3d 09 00 00 00 00 43 c7 44 3d RSP: 0018:ffffc90009e06560 EFLAGS: 00000206 RAX: 1ffff920013c0cc0 RBX: 0000000000000246 RCX: dffffc0000000000 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: ffffc90009e066e0 R08: dffffc0000000000 R09: fffffbfff1f992b1 R10: fffffbfff1f992b1 R11: 0000000000000000 R12: 0000000000000000 R13: dffffc0000000000 R14: 0000000000000000 R15: 1ffff920013c0cb4 rcu_lock_acquire+0x2a/0x30 include/linux/rcupdate.h:267 rcu_read_lock include/linux/rcupdate.h:656 [inline] ext4_get_group_info+0xea/0x340 fs/ext4/ext4.h:3231 ext4_mb_prefetch+0x123/0x5d0 fs/ext4/mballoc.c:2212 ext4_mb_regular_allocator+0x8a5/0x28f0 fs/ext4/mballoc.c:2379 ext4_mb_new_blocks+0xc6e/0x24f0 fs/ext4/mballoc.c:4982 ext4_ext_map_blocks+0x2be3/0x7210 fs/ext4/extents.c:4238 ext4_map_blocks+0xab3/0x1cb0 fs/ext4/inode.c:638 ext4_getblk+0x187/0x6c0 fs/ext4/inode.c:848 ext4_bread+0x2a/0x1c0 fs/ext4/inode.c:900 ext4_append+0x1a4/0x360 fs/ext4/namei.c:67 ext4_init_new_dir+0x337/0xa10 fs/ext4/namei.c:2768 ext4_mkdir+0x4b8/0xc00 fs/ext4/namei.c:2814 vfs_mkdir+0x45b/0x640 fs/namei.c:3819 ovl_do_mkdir fs/overlayfs/overlayfs.h:161 [inline] ovl_mkdir_real+0x53/0x1a0 fs/overlayfs/dir.c:146 ovl_create_real+0x280/0x490 fs/overlayfs/dir.c:193 ovl_workdir_create+0x425/0x600 fs/overlayfs/super.c:788 ovl_make_workdir+0xed/0x1140 fs/overlayfs/super.c:1355 ovl_get_workdir fs/overlayfs/super.c:1492 [inline] ovl_fill_super+0x39ee/0x5370 fs/overlayfs/super.c:2035 mount_nodev+0x52/0xe0 fs/super.c:1413 legacy_get_tree+0xea/0x180 fs/fs_context.c:592 vfs_get_tree+0x86/0x270 fs/super.c:1497 do_new_mount fs/namespace.c:2903 [inline] path_mount+0x196f/0x2be0 fs/namespace.c:3233 do_mount fs/namespace.c:3246 [inline] __do_sys_mount fs/namespace.c:3454 [inline] __se_sys_mount+0x2f9/0x3b0 fs/namespace.c:3431 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x4665f9 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 bc ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f68f2b87188 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5 RAX: ffffffffffffffda RBX: 000000000056bf60 RCX: 00000000004665f9 RDX: 00000000200000c0 RSI: 0000000020000000 RDI: 000000000040000a RBP: 00000000004bfbb9 R08: 0000000020000100 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000056bf60 R13: 00007ffe19002dff R14: 00007f68f2b87300 R15: 0000000000022000 Allocated by task 17768: kasan_save_stack mm/kasan/common.c:38 [inline] kasan_set_track mm/kasan/common.c:46 [inline] set_alloc_info mm/kasan/common.c:427 [inline] ____kasan_kmalloc+0xc2/0xf0 mm/kasan/common.c:506 kasan_kmalloc include/linux/kasan.h:233 [inline] __kmalloc+0xb4/0x380 mm/slub.c:4055 kmalloc include/linux/slab.h:559 [inline] kzalloc include/linux/slab.h:684 [inline] fib6_info_alloc+0x2c/0xd0 net/ipv6/ip6_fib.c:154 ip6_route_info_create+0x55d/0x1a10 net/ipv6/route.c:3638 ip6_route_add+0x22/0x120 net/ipv6/route.c:3728 inet6_rtm_newroute+0x2cd/0x2260 net/ipv6/route.c:5352 rtnetlink_rcv_msg+0xb34/0xe70 net/core/rtnetlink.c:5553 netlink_rcv_skb+0x1f0/0x460 net/netlink/af_netlink.c:2502 netlink_unicast_kernel net/netlink/af_netlink.c:1312 [inline] netlink_unicast+0x7de/0x9b0 net/netlink/af_netlink.c:1338 netlink_sendmsg+0xaa6/0xe90 net/netlink/af_netlink.c:1927 sock_sendmsg_nosec net/socket.c:654 [inline] sock_sendmsg net/socket.c:674 [inline] ____sys_sendmsg+0x5a2/0x900 net/socket.c:2350 ___sys_sendmsg net/socket.c:2404 [inline] __sys_sendmsg+0x319/0x400 net/socket.c:2433 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xae Last potentially related work creation: kasan_save_stack+0x27/0x50 mm/kasan/common.c:38 kasan_record_aux_stack+0xee/0x120 mm/kasan/generic.c:345 __call_rcu kernel/rcu/tree.c:3039 [inline] call_rcu+0x1b1/0xa30 kernel/rcu/tree.c:3114 fib6_info_release include/net/ip6_fib.h:337 [inline] ip6_route_info_create+0x10c4/0x1a10 net/ipv6/route.c:3718 ip6_route_add+0x22/0x120 net/ipv6/route.c:3728 inet6_rtm_newroute+0x2cd/0x2260 net/ipv6/route.c:5352 rtnetlink_rcv_msg+0xb34/0xe70 net/core/rtnetlink.c:5553 netlink_rcv_skb+0x1f0/0x460 net/netlink/af_netlink.c:2502 netlink_unicast_kernel net/netlink/af_netlink.c:1312 [inline] netlink_unicast+0x7de/0x9b0 net/netlink/af_netlink.c:1338 netlink_sendmsg+0xaa6/0xe90 net/netlink/af_netlink.c:1927 sock_sendmsg_nosec net/socket.c:654 [inline] sock_sendmsg net/socket.c:674 [inline] ____sys_sendmsg+0x5a2/0x900 net/socket.c:2350 ___sys_sendmsg net/socket.c:2404 [inline] __sys_sendmsg+0x319/0x400 net/socket.c:2433 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xae Second to last potentially related work creation: kasan_save_stack+0x27/0x50 mm/kasan/common.c:38 kasan_record_aux_stack+0xee/0x120 mm/kasan/generic.c:345 insert_work+0x54/0x400 kernel/workqueue.c:1331 __queue_work+0x981/0xcc0 kernel/workqueue.c:1497 queue_work_on+0x111/0x200 kernel/workqueue.c:1524 queue_work include/linux/workqueue.h:507 [inline] call_usermodehelper_exec+0x283/0x470 kernel/umh.c:433 kobject_uevent_env+0x1349/0x1730 lib/kobject_uevent.c:617 kvm_uevent_notify_change+0x309/0x3b0 arch/x86/kvm/../../../virt/kvm/kvm_main.c:4809 kvm_destroy_vm arch/x86/kvm/../../../virt/kvm/kvm_main.c:877 [inline] kvm_put_kvm+0x9c/0xd10 arch/x86/kvm/../../../virt/kvm/kvm_main.c:920 kvm_vcpu_release+0x53/0x60 arch/x86/kvm/../../../virt/kvm/kvm_main.c:3120 __fput+0x352/0x7b0 fs/file_table.c:280 task_work_run+0x146/0x1c0 kernel/task_work.c:140 tracehook_notify_resume include/linux/tracehook.h:189 [inline] exit_to_user_mode_loop kernel/entry/common.c:174 [inline] exit_to_user_mode_prepare+0x10b/0x1e0 kernel/entry/common.c:208 __syscall_exit_to_user_mode_work kernel/entry/common.c:290 [inline] syscall_exit_to_user_mode+0x26/0x70 kernel/entry/common.c:301 entry_SYSCALL_64_after_hwframe+0x44/0xae The buggy address belongs to the object at ffff8880145c7800 which belongs to the cache kmalloc-192 of size 192 The buggy address is located 56 bytes to the right of 192-byte region [ffff8880145c7800, ffff8880145c78c0) The buggy address belongs to the page: page:ffffea00005171c0 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x145c7 flags: 0xfff00000000200(slab) raw: 00fff00000000200 ffffea00006474c0 0000000200000002 ffff888010c41a00 raw: 0000000000000000 0000000080100010 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff8880145c7780: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc ffff8880145c7800: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 >ffff8880145c7880: 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc fc ^ ffff8880145c7900: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ffff8880145c7980: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc ================================================================== In the ip6_route_info_create function, in the case that the nh pointer is not NULL, the fib6_nh in fib6_info has not been allocated. Therefore, when trying to free fib6_info in this error case using fib6_info_release, the function will call fib6_info_destroy_rcu, which it will access fib6_nh_release(f6i->fib6_nh); However, f6i->fib6_nh doesn't have any refcount yet given the lack of allocation causing the reported memory issue above. Therefore, releasing the empty pointer directly instead would be the solution. The Linux kernel CVE team has assigned CVE-2021-47126 to this issue. Affected and fixed versions =========================== Issue introduced in 5.3 with commit 706ec91916462 and fixed in 5.4.125 with commit 7ba7fa78a92d Issue introduced in 5.3 with commit 706ec91916462 and fixed in 5.10.43 with commit 098702358274 Issue introduced in 5.3 with commit 706ec91916462 and fixed in 5.12.10 with commit 0a462e25ef0f Issue introduced in 5.3 with commit 706ec91916462 and fixed in 5.13 with commit 821bbf79fe46 Please see https://www.kernel.org or a full list of currently supported kernel versions by the kernel community. Unaffected versions might change over time as fixes are backported to older supported kernel versions. The official CVE entry at https://cve.org/CVERecord/?id=CVE-2021-47126 will be updated if fixes are backported, please check that for the most up to date information about this issue. Affected files ============== The file(s) affected by this issue are: net/ipv6/route.c Mitigation ========== The Linux kernel CVE team recommends that you update to the latest stable kernel version for this, and many other bugfixes. Individual changes are never tested alone, but rather are part of a larger kernel release. Cherry-picking individual commits is not recommended or supported by the Linux kernel community at all. If however, updating to the latest release is impossible, the individual changes to resolve this issue can be found at these commits: https://git.kernel.org/stable/c/7ba7fa78a92dc410b6f93ed73075ab669c3a0b59 https://git.kernel.org/stable/c/09870235827451409ff546b073d754a19fd17e2e https://git.kernel.org/stable/c/0a462e25ef0f7ab305081a08d435bbd1f13c0a94 https://git.kernel.org/stable/c/821bbf79fe46a8b1d18aa456e8ed0a3c208c3754
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