From: Lin Ma linma@zju.edu.cn
[ Upstream commit dfa73c17d55b921e1d4e154976de35317e43a93a ]
We found below OOB crash:
[ 44.211730] ================================================================== [ 44.212045] BUG: KASAN: slab-out-of-bounds in memcmp+0x8b/0xb0 [ 44.212045] Read of size 8 at addr ffff88800870f320 by task poc.xfrm/97 [ 44.212045] [ 44.212045] CPU: 0 PID: 97 Comm: poc.xfrm Not tainted 6.4.0-rc7-00072-gdad9774deaf1-dirty #4 [ 44.212045] Call Trace: [ 44.212045] <TASK> [ 44.212045] dump_stack_lvl+0x37/0x50 [ 44.212045] print_report+0xcc/0x620 [ 44.212045] ? __virt_addr_valid+0xf3/0x170 [ 44.212045] ? memcmp+0x8b/0xb0 [ 44.212045] kasan_report+0xb2/0xe0 [ 44.212045] ? memcmp+0x8b/0xb0 [ 44.212045] kasan_check_range+0x39/0x1c0 [ 44.212045] memcmp+0x8b/0xb0 [ 44.212045] xfrm_state_walk+0x21c/0x420 [ 44.212045] ? __pfx_dump_one_state+0x10/0x10 [ 44.212045] xfrm_dump_sa+0x1e2/0x290 [ 44.212045] ? __pfx_xfrm_dump_sa+0x10/0x10 [ 44.212045] ? __kernel_text_address+0xd/0x40 [ 44.212045] ? kasan_unpoison+0x27/0x60 [ 44.212045] ? mutex_lock+0x60/0xe0 [ 44.212045] ? __pfx_mutex_lock+0x10/0x10 [ 44.212045] ? kasan_save_stack+0x22/0x50 [ 44.212045] netlink_dump+0x322/0x6c0 [ 44.212045] ? __pfx_netlink_dump+0x10/0x10 [ 44.212045] ? mutex_unlock+0x7f/0xd0 [ 44.212045] ? __pfx_mutex_unlock+0x10/0x10 [ 44.212045] __netlink_dump_start+0x353/0x430 [ 44.212045] xfrm_user_rcv_msg+0x3a4/0x410 [ 44.212045] ? __pfx__raw_spin_lock_irqsave+0x10/0x10 [ 44.212045] ? __pfx_xfrm_user_rcv_msg+0x10/0x10 [ 44.212045] ? __pfx_xfrm_dump_sa+0x10/0x10 [ 44.212045] ? __pfx_xfrm_dump_sa_done+0x10/0x10 [ 44.212045] ? __stack_depot_save+0x382/0x4e0 [ 44.212045] ? filter_irq_stacks+0x1c/0x70 [ 44.212045] ? kasan_save_stack+0x32/0x50 [ 44.212045] ? kasan_save_stack+0x22/0x50 [ 44.212045] ? kasan_set_track+0x25/0x30 [ 44.212045] ? __kasan_slab_alloc+0x59/0x70 [ 44.212045] ? kmem_cache_alloc_node+0xf7/0x260 [ 44.212045] ? kmalloc_reserve+0xab/0x120 [ 44.212045] ? __alloc_skb+0xcf/0x210 [ 44.212045] ? netlink_sendmsg+0x509/0x700 [ 44.212045] ? sock_sendmsg+0xde/0xe0 [ 44.212045] ? __sys_sendto+0x18d/0x230 [ 44.212045] ? __x64_sys_sendto+0x71/0x90 [ 44.212045] ? do_syscall_64+0x3f/0x90 [ 44.212045] ? entry_SYSCALL_64_after_hwframe+0x72/0xdc [ 44.212045] ? netlink_sendmsg+0x509/0x700 [ 44.212045] ? sock_sendmsg+0xde/0xe0 [ 44.212045] ? __sys_sendto+0x18d/0x230 [ 44.212045] ? __x64_sys_sendto+0x71/0x90 [ 44.212045] ? do_syscall_64+0x3f/0x90 [ 44.212045] ? entry_SYSCALL_64_after_hwframe+0x72/0xdc [ 44.212045] ? kasan_save_stack+0x22/0x50 [ 44.212045] ? kasan_set_track+0x25/0x30 [ 44.212045] ? kasan_save_free_info+0x2e/0x50 [ 44.212045] ? __kasan_slab_free+0x10a/0x190 [ 44.212045] ? kmem_cache_free+0x9c/0x340 [ 44.212045] ? netlink_recvmsg+0x23c/0x660 [ 44.212045] ? sock_recvmsg+0xeb/0xf0 [ 44.212045] ? __sys_recvfrom+0x13c/0x1f0 [ 44.212045] ? __x64_sys_recvfrom+0x71/0x90 [ 44.212045] ? do_syscall_64+0x3f/0x90 [ 44.212045] ? entry_SYSCALL_64_after_hwframe+0x72/0xdc [ 44.212045] ? copyout+0x3e/0x50 [ 44.212045] netlink_rcv_skb+0xd6/0x210 [ 44.212045] ? __pfx_xfrm_user_rcv_msg+0x10/0x10 [ 44.212045] ? __pfx_netlink_rcv_skb+0x10/0x10 [ 44.212045] ? __pfx_sock_has_perm+0x10/0x10 [ 44.212045] ? mutex_lock+0x8d/0xe0 [ 44.212045] ? __pfx_mutex_lock+0x10/0x10 [ 44.212045] xfrm_netlink_rcv+0x44/0x50 [ 44.212045] netlink_unicast+0x36f/0x4c0 [ 44.212045] ? __pfx_netlink_unicast+0x10/0x10 [ 44.212045] ? netlink_recvmsg+0x500/0x660 [ 44.212045] netlink_sendmsg+0x3b7/0x700 [ 44.212045] ? __pfx_netlink_sendmsg+0x10/0x10 [ 44.212045] ? __pfx_netlink_sendmsg+0x10/0x10 [ 44.212045] sock_sendmsg+0xde/0xe0 [ 44.212045] __sys_sendto+0x18d/0x230 [ 44.212045] ? __pfx___sys_sendto+0x10/0x10 [ 44.212045] ? rcu_core+0x44a/0xe10 [ 44.212045] ? __rseq_handle_notify_resume+0x45b/0x740 [ 44.212045] ? _raw_spin_lock_irq+0x81/0xe0 [ 44.212045] ? __pfx___rseq_handle_notify_resume+0x10/0x10 [ 44.212045] ? __pfx_restore_fpregs_from_fpstate+0x10/0x10 [ 44.212045] ? __pfx_blkcg_maybe_throttle_current+0x10/0x10 [ 44.212045] ? __pfx_task_work_run+0x10/0x10 [ 44.212045] __x64_sys_sendto+0x71/0x90 [ 44.212045] do_syscall_64+0x3f/0x90 [ 44.212045] entry_SYSCALL_64_after_hwframe+0x72/0xdc [ 44.212045] RIP: 0033:0x44b7da [ 44.212045] RSP: 002b:00007ffdc8838548 EFLAGS: 00000246 ORIG_RAX: 000000000000002c [ 44.212045] RAX: ffffffffffffffda RBX: 00007ffdc8839978 RCX: 000000000044b7da [ 44.212045] RDX: 0000000000000038 RSI: 00007ffdc8838770 RDI: 0000000000000003 [ 44.212045] RBP: 00007ffdc88385b0 R08: 00007ffdc883858c R09: 000000000000000c [ 44.212045] R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001 [ 44.212045] R13: 00007ffdc8839968 R14: 00000000004c37d0 R15: 0000000000000001 [ 44.212045] </TASK> [ 44.212045] [ 44.212045] Allocated by task 97: [ 44.212045] kasan_save_stack+0x22/0x50 [ 44.212045] kasan_set_track+0x25/0x30 [ 44.212045] __kasan_kmalloc+0x7f/0x90 [ 44.212045] __kmalloc_node_track_caller+0x5b/0x140 [ 44.212045] kmemdup+0x21/0x50 [ 44.212045] xfrm_dump_sa+0x17d/0x290 [ 44.212045] netlink_dump+0x322/0x6c0 [ 44.212045] __netlink_dump_start+0x353/0x430 [ 44.212045] xfrm_user_rcv_msg+0x3a4/0x410 [ 44.212045] netlink_rcv_skb+0xd6/0x210 [ 44.212045] xfrm_netlink_rcv+0x44/0x50 [ 44.212045] netlink_unicast+0x36f/0x4c0 [ 44.212045] netlink_sendmsg+0x3b7/0x700 [ 44.212045] sock_sendmsg+0xde/0xe0 [ 44.212045] __sys_sendto+0x18d/0x230 [ 44.212045] __x64_sys_sendto+0x71/0x90 [ 44.212045] do_syscall_64+0x3f/0x90 [ 44.212045] entry_SYSCALL_64_after_hwframe+0x72/0xdc [ 44.212045] [ 44.212045] The buggy address belongs to the object at ffff88800870f300 [ 44.212045] which belongs to the cache kmalloc-64 of size 64 [ 44.212045] The buggy address is located 32 bytes inside of [ 44.212045] allocated 36-byte region [ffff88800870f300, ffff88800870f324) [ 44.212045] [ 44.212045] The buggy address belongs to the physical page: [ 44.212045] page:00000000e4de16ee refcount:1 mapcount:0 mapping:000000000 ... [ 44.212045] flags: 0x100000000000200(slab|node=0|zone=1) [ 44.212045] page_type: 0xffffffff() [ 44.212045] raw: 0100000000000200 ffff888004c41640 dead000000000122 0000000000000000 [ 44.212045] raw: 0000000000000000 0000000080200020 00000001ffffffff 0000000000000000 [ 44.212045] page dumped because: kasan: bad access detected [ 44.212045] [ 44.212045] Memory state around the buggy address: [ 44.212045] ffff88800870f200: fa fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc [ 44.212045] ffff88800870f280: 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc [ 44.212045] >ffff88800870f300: 00 00 00 00 04 fc fc fc fc fc fc fc fc fc fc fc [ 44.212045] ^ [ 44.212045] ffff88800870f380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 44.212045] ffff88800870f400: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc [ 44.212045] ==================================================================
By investigating the code, we find the root cause of this OOB is the lack of checks in xfrm_dump_sa(). The buggy code allows a malicious user to pass arbitrary value of filter->splen/dplen. Hence, with crafted xfrm states, the attacker can achieve 8 bytes heap OOB read, which causes info leak.
if (attrs[XFRMA_ADDRESS_FILTER]) { filter = kmemdup(nla_data(attrs[XFRMA_ADDRESS_FILTER]), sizeof(*filter), GFP_KERNEL); if (filter == NULL) return -ENOMEM; // NO MORE CHECKS HERE !!! }
This patch fixes the OOB by adding necessary boundary checks, just like the code in pfkey_dump() function.
Fixes: d3623099d350 ("ipsec: add support of limited SA dump") Signed-off-by: Lin Ma linma@zju.edu.cn Signed-off-by: Steffen Klassert steffen.klassert@secunet.com Signed-off-by: Sasha Levin sashal@kernel.org --- net/xfrm/xfrm_user.c | 9 +++++++++ 1 file changed, 9 insertions(+)
diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c index eb0952dbf4236..b2065f69c3d2c 100644 --- a/net/xfrm/xfrm_user.c +++ b/net/xfrm/xfrm_user.c @@ -1159,6 +1159,15 @@ static int xfrm_dump_sa(struct sk_buff *skb, struct netlink_callback *cb) sizeof(*filter), GFP_KERNEL); if (filter == NULL) return -ENOMEM; + + /* see addr_match(), (prefix length >> 5) << 2 + * will be used to compare xfrm_address_t + */ + if (filter->splen > (sizeof(xfrm_address_t) << 3) || + filter->dplen > (sizeof(xfrm_address_t) << 3)) { + kfree(filter); + return -EINVAL; + } }
if (attrs[XFRMA_PROTO])