6.5-stable review patch. If anyone has any objections, please let me know.
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From: Dong Chenchen dongchenchen2@huawei.com
commit 6d41d4fe28724db16ca1016df0713a07e0cc7448 upstream.
BUG: KASAN: slab-use-after-free in xfrm_policy_inexact_list_reinsert+0xb6/0x430 Read of size 1 at addr ffff8881051f3bf8 by task ip/668
CPU: 2 PID: 668 Comm: ip Not tainted 6.5.0-rc5-00182-g25aa0bebba72-dirty #64 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.13 04/01/2014 Call Trace: <TASK> dump_stack_lvl+0x72/0xa0 print_report+0xd0/0x620 kasan_report+0xb6/0xf0 xfrm_policy_inexact_list_reinsert+0xb6/0x430 xfrm_policy_inexact_insert_node.constprop.0+0x537/0x800 xfrm_policy_inexact_alloc_chain+0x23f/0x320 xfrm_policy_inexact_insert+0x6b/0x590 xfrm_policy_insert+0x3b1/0x480 xfrm_add_policy+0x23c/0x3c0 xfrm_user_rcv_msg+0x2d0/0x510 netlink_rcv_skb+0x10d/0x2d0 xfrm_netlink_rcv+0x49/0x60 netlink_unicast+0x3fe/0x540 netlink_sendmsg+0x528/0x970 sock_sendmsg+0x14a/0x160 ____sys_sendmsg+0x4fc/0x580 ___sys_sendmsg+0xef/0x160 __sys_sendmsg+0xf7/0x1b0 do_syscall_64+0x3f/0x90 entry_SYSCALL_64_after_hwframe+0x73/0xdd
The root cause is:
cpu 0 cpu1 xfrm_dump_policy xfrm_policy_walk list_move_tail xfrm_add_policy ... ... xfrm_policy_inexact_list_reinsert list_for_each_entry_reverse if (!policy->bydst_reinsert) //read non-existent policy xfrm_dump_policy_done xfrm_policy_walk_done list_del(&walk->walk.all);
If dump_one_policy() returns err (triggered by netlink socket), xfrm_policy_walk() will move walk initialized by socket to list net->xfrm.policy_all. so this socket becomes visible in the global policy list. The head *walk can be traversed when users add policies with different prefixlen and trigger xfrm_policy node merge.
The issue can also be triggered by policy list traversal while rehashing and flushing policies.
It can be fixed by skip such "policies" with walk.dead set to 1.
Fixes: 9cf545ebd591 ("xfrm: policy: store inexact policies in a tree ordered by destination address") Fixes: 12a169e7d8f4 ("ipsec: Put dumpers on the dump list") Signed-off-by: Dong Chenchen dongchenchen2@huawei.com Signed-off-by: Steffen Klassert steffen.klassert@secunet.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/xfrm/xfrm_policy.c | 19 +++++++++++++------ 1 file changed, 13 insertions(+), 6 deletions(-)
--- a/net/xfrm/xfrm_policy.c +++ b/net/xfrm/xfrm_policy.c @@ -851,7 +851,7 @@ static void xfrm_policy_inexact_list_rei struct hlist_node *newpos = NULL; bool matches_s, matches_d;
- if (!policy->bydst_reinsert) + if (policy->walk.dead || !policy->bydst_reinsert) continue;
WARN_ON_ONCE(policy->family != family); @@ -1256,8 +1256,11 @@ static void xfrm_hash_rebuild(struct wor struct xfrm_pol_inexact_bin *bin; u8 dbits, sbits;
+ if (policy->walk.dead) + continue; + dir = xfrm_policy_id2dir(policy->index); - if (policy->walk.dead || dir >= XFRM_POLICY_MAX) + if (dir >= XFRM_POLICY_MAX) continue;
if ((dir & XFRM_POLICY_MASK) == XFRM_POLICY_OUT) { @@ -1821,9 +1824,11 @@ int xfrm_policy_flush(struct net *net, u
again: list_for_each_entry(pol, &net->xfrm.policy_all, walk.all) { + if (pol->walk.dead) + continue; + dir = xfrm_policy_id2dir(pol->index); - if (pol->walk.dead || - dir >= XFRM_POLICY_MAX || + if (dir >= XFRM_POLICY_MAX || pol->type != type) continue;
@@ -1860,9 +1865,11 @@ int xfrm_dev_policy_flush(struct net *ne
again: list_for_each_entry(pol, &net->xfrm.policy_all, walk.all) { + if (pol->walk.dead) + continue; + dir = xfrm_policy_id2dir(pol->index); - if (pol->walk.dead || - dir >= XFRM_POLICY_MAX || + if (dir >= XFRM_POLICY_MAX || pol->xdo.dev != dev) continue;