From: Hoang Le hoang.h.le@dektech.com.au
[ 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: af9b028e270fd ("tipc: make media xmit call outside node spinlock context") Acked-by: Jon Maloy jmaloy@redhat.com Signed-off-by: Hoang 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: Jakub Kicinski kuba@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/tipc/link.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-)
--- a/net/tipc/link.c +++ b/net/tipc/link.c @@ -877,9 +877,8 @@ 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; - unsigned int i, imp = msg_importance(hdr); + unsigned int i; unsigned int mtu = l->mtu; u16 ack = l->rcv_nxt - 1; u16 seqno = l->snd_nxt; @@ -888,7 +887,13 @@ int tipc_link_xmit(struct tipc_link *l, struct sk_buff_head *backlogq = &l->backlogq; struct sk_buff *skb, *_skb, *bskb; int pkt_cnt = skb_queue_len(list); + struct tipc_msg *hdr; + int imp;
+ if (pkt_cnt <= 0) + return 0; + + imp = msg_importance(hdr); /* Match msg importance against this and all higher backlog limits: */ if (!skb_queue_empty(backlogq)) { for (i = imp; i <= TIPC_SYSTEM_IMPORTANCE; i++) { @@ -896,6 +901,8 @@ int tipc_link_xmit(struct tipc_link *l, return link_schedule_user(l, list); } } + + hdr = buf_msg(skb_peek(list)); if (unlikely(msg_size(hdr) > mtu)) { skb_queue_purge(list); return -EMSGSIZE;