| From foo@baz Fri Jan 22 12:59:03 PM CET 2021 |
| From: Hoang Le <hoang.h.le@dektech.com.au> |
| Date: Fri, 8 Jan 2021 14:13:37 +0700 |
| Subject: tipc: fix NULL deref in tipc_link_xmit() |
| |
| 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 | 9 +++++++-- |
| 1 file changed, 7 insertions(+), 2 deletions(-) |
| |
| --- a/net/tipc/link.c |
| +++ b/net/tipc/link.c |
| @@ -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 *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) { |
