| Message ID | 20230728121703.29572-1-yuehaibing@huawei.com (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [v2] ip6mr: Fix skb_under_panic in ip6mr_cache_report() | expand |
On Fri, 28 Jul 2023 20:17:03 +0800 Yue Haibing wrote: > #ifdef CONFIG_IPV6_PIMSM_V2 > + int nhoff = skb_network_offset(pkt); > if (assert == MRT6MSG_WHOLEPKT || assert == MRT6MSG_WRMIFWHOLE) > - skb = skb_realloc_headroom(pkt, -skb_network_offset(pkt) > - +sizeof(*msg)); > + skb = skb_realloc_headroom(pkt, -nhoff + sizeof(*msg)); These changes look unnecessary. You can leave this code be (as ugly as it is)... > else > #endif > skb = alloc_skb(sizeof(struct ipv6hdr) + sizeof(*msg), GFP_ATOMIC); > @@ -1073,7 +1073,7 @@ static int ip6mr_cache_report(const struct mr_table *mrt, struct sk_buff *pkt, > And all this only to mangle msg->im6_msgtype and > to set msg->im6_mbz to "mbz" :-) > */ > - skb_push(skb, -skb_network_offset(pkt)); > + __skb_pull(skb, nhoff); .. and just replace the push here with: __skb_pull(skb, skb_network_offset(pkt));
On 2023/8/1 11:09, Jakub Kicinski wrote: > On Fri, 28 Jul 2023 20:17:03 +0800 Yue Haibing wrote: >> #ifdef CONFIG_IPV6_PIMSM_V2 >> + int nhoff = skb_network_offset(pkt); >> if (assert == MRT6MSG_WHOLEPKT || assert == MRT6MSG_WRMIFWHOLE) >> - skb = skb_realloc_headroom(pkt, -skb_network_offset(pkt) >> - +sizeof(*msg)); >> + skb = skb_realloc_headroom(pkt, -nhoff + sizeof(*msg)); > > These changes look unnecessary. You can leave this code be (as ugly as > it is)... > >> else >> #endif >> skb = alloc_skb(sizeof(struct ipv6hdr) + sizeof(*msg), GFP_ATOMIC); >> @@ -1073,7 +1073,7 @@ static int ip6mr_cache_report(const struct mr_table *mrt, struct sk_buff *pkt, >> And all this only to mangle msg->im6_msgtype and >> to set msg->im6_mbz to "mbz" :-) >> */ >> - skb_push(skb, -skb_network_offset(pkt)); >> + __skb_pull(skb, nhoff); > > .. and just replace the push here with: > > __skb_pull(skb, skb_network_offset(pkt)); Thanks， will do this in v3. >
diff --git a/net/ipv6/ip6mr.c b/net/ipv6/ip6mr.c index cc3d5ad17257..1a55d41feaa6 100644 --- a/net/ipv6/ip6mr.c +++ b/net/ipv6/ip6mr.c @@ -1051,9 +1051,9 @@ static int ip6mr_cache_report(const struct mr_table *mrt, struct sk_buff *pkt, int ret; #ifdef CONFIG_IPV6_PIMSM_V2 + int nhoff = skb_network_offset(pkt); if (assert == MRT6MSG_WHOLEPKT || assert == MRT6MSG_WRMIFWHOLE) - skb = skb_realloc_headroom(pkt, -skb_network_offset(pkt) - +sizeof(*msg)); + skb = skb_realloc_headroom(pkt, -nhoff + sizeof(*msg)); else #endif skb = alloc_skb(sizeof(struct ipv6hdr) + sizeof(*msg), GFP_ATOMIC); @@ -1073,7 +1073,7 @@ static int ip6mr_cache_report(const struct mr_table *mrt, struct sk_buff *pkt, And all this only to mangle msg->im6_msgtype and to set msg->im6_mbz to "mbz" :-) */ - skb_push(skb, -skb_network_offset(pkt)); + __skb_pull(skb, nhoff); skb_push(skb, sizeof(*msg)); skb_reset_transport_header(skb);
skbuff: skb_under_panic: text:ffffffff88771f69 len:56 put:-4 head:ffff88805f86a800 data:ffff887f5f86a850 tail:0x88 end:0x2c0 dev:pim6reg ------------[ cut here ]------------ kernel BUG at net/core/skbuff.c:192! invalid opcode: 0000 [#1] PREEMPT SMP KASAN CPU: 2 PID: 22968 Comm: kworker/2:11 Not tainted 6.5.0-rc3-00044-g0a8db05b571a #236 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014 Workqueue: ipv6_addrconf addrconf_dad_work RIP: 0010:skb_panic+0x152/0x1d0 Call Trace: <TASK> skb_push+0xc4/0xe0 ip6mr_cache_report+0xd69/0x19b0 reg_vif_xmit+0x406/0x690 dev_hard_start_xmit+0x17e/0x6e0 __dev_queue_xmit+0x2d6a/0x3d20 vlan_dev_hard_start_xmit+0x3ab/0x5c0 dev_hard_start_xmit+0x17e/0x6e0 __dev_queue_xmit+0x2d6a/0x3d20 neigh_connected_output+0x3ed/0x570 ip6_finish_output2+0x5b5/0x1950 ip6_finish_output+0x693/0x11c0 ip6_output+0x24b/0x880 NF_HOOK.constprop.0+0xfd/0x530 ndisc_send_skb+0x9db/0x1400 ndisc_send_rs+0x12a/0x6c0 addrconf_dad_completed+0x3c9/0xea0 addrconf_dad_work+0x849/0x1420 process_one_work+0xa22/0x16e0 worker_thread+0x679/0x10c0 ret_from_fork+0x28/0x60 ret_from_fork_asm+0x11/0x20 When setup a vlan device on dev pim6reg, DAD ns packet may sent on reg_vif_xmit(). reg_vif_xmit() ip6mr_cache_report() skb_push(skb, -skb_network_offset(pkt));//skb_network_offset(pkt) is 4 And skb_push declared as: void *skb_push(struct sk_buff *skb, unsigned int len); skb->data -= len; //0xffff88805f86a84c - 0xfffffffc = 0xffff887f5f86a850 skb->data is set to 0xffff887f5f86a850, which is invalid mem addr, lead to skb_push() fails. Fixes: 14fb64e1f449 ("[IPV6] MROUTE: Support PIM-SM (SSM).") Signed-off-by: Yue Haibing <yuehaibing@huawei.com> --- v2: Use __skb_pull() and fix commit log. --- net/ipv6/ip6mr.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)