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Commit 4d1d3ddd authored by Hoang Le's avatar Hoang Le Committed by Greg Kroah-Hartman
Browse files

tipc: fix NULL deref in tipc_link_xmit() 



[ Upstream commit b77413446408fdd256599daf00d5be72b5f3e7c6 ]

The buffer list can have zero skb as following path:
tipc_named_node_up()->tipc_node_xmit()->tipc_link_xmit(), so
we need to check the list before casting an &sk_buff.

Fault report:
 [] tipc: Bulk publication failure
 [] general protection fault, probably for non-canonical [#1] PREEMPT [...]
 [] KASAN: null-ptr-deref in range [0x00000000000000c8-0x00000000000000cf]
 [] CPU: 0 PID: 0 Comm: swapper/0 Kdump: loaded Not tainted 5.10.0-rc4+ #2
 [] Hardware name: Bochs ..., BIOS Bochs 01/01/2011
 [] RIP: 0010:tipc_link_xmit+0xc1/0x2180
 [] Code: 24 b8 00 00 00 00 4d 39 ec 4c 0f 44 e8 e8 d7 0a 10 f9 48 [...]
 [] RSP: 0018:ffffc90000006ea0 EFLAGS: 00010202
 [] RAX: dffffc0000000000 RBX: ffff8880224da000 RCX: 1ffff11003d3cc0d
 [] RDX: 0000000000000019 RSI: ffffffff886007b9 RDI: 00000000000000c8
 [] RBP: ffffc90000007018 R08: 0000000000000001 R09: fffff52000000ded
 [] R10: 0000000000000003 R11: fffff52000000dec R12: ffffc90000007148
 [] R13: 0000000000000000 R14: 0000000000000000 R15: ffffc90000007018
 [] FS:  0000000000000000(0000) GS:ffff888037400000(0000) knlGS:000[...]
 [] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 [] CR2: 00007fffd2db5000 CR3: 000000002b08f000 CR4: 00000000000006f0

Fixes: af9b028e ("tipc: make media xmit call outside node spinlock context")
Acked-by: default avatarJon Maloy <jmaloy@redhat.com>
Signed-off-by: default avatarHoang Le <hoang.h.le@dektech.com.au>
Link: https://lore.kernel.org/r/20210108071337.3598-1-hoang.h.le@dektech.com.au


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent d9364c8f

net/tipc/link.c

+7 −2
Original line number Diff line number Diff line
@@ -914,9 +914,7 @@ void tipc_link_reset(struct tipc_link *l) 
int tipc_link_xmit(struct tipc_link *l, struct sk_buff_head *list,

		   struct sk_buff_head *xmitq)

{

	struct tipc_msg *hdr = buf_msg(skb_peek(list));

	unsigned int maxwin = l->window;

	int imp = msg_importance(hdr);

	unsigned int mtu = l->mtu;

	u16 ack = l->rcv_nxt - 1;

	u16 seqno = l->snd_nxt;
@@ -925,13 +923,20 @@ int tipc_link_xmit(struct tipc_link *l, struct sk_buff_head *list, 
	struct sk_buff_head *backlogq = &l->backlogq;

	struct sk_buff *skb, *_skb, **tskb;

	int pkt_cnt = skb_queue_len(list);

	struct tipc_msg *hdr;

	int rc = 0;

	int imp;



	if (pkt_cnt <= 0)

		return 0;



	hdr = buf_msg(skb_peek(list));

	if (unlikely(msg_size(hdr) > mtu)) {

		__skb_queue_purge(list);

		return -EMSGSIZE;

	}



	imp = msg_importance(hdr);

	/* Allow oversubscription of one data msg per source at congestion */

	if (unlikely(l->backlog[imp].len >= l->backlog[imp].limit)) {

		if (imp == TIPC_SYSTEM_IMPORTANCE) {