| Message ID | 1667213123-18922-1-git-send-email-wangyufen@huawei.com (mailing list archive) |
|---|---|
| State | Changes Requested |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [net] net: Fix memory leaks in napi_get_frags_check() | expand |
Ignore, this fix is wrong. 在 2022/10/31 18:45, Wang Yufen 写道: > kmemleak reports this issue: > > unreferenced object 0xffff88819b8c97c0 (size 232): > comm "ip", pid 2915, jiffies 4295153830 (age 408.877s) > hex dump (first 32 bytes): > 00 80 8c 9b 81 88 ff ff e0 24 f7 12 81 88 ff ff .........$...... > 00 40 05 c0 81 88 ff ff 00 00 00 00 00 00 00 00 .@.............. > backtrace: > [<0000000009fc179a>] napi_skb_cache_get+0xd4/0x150 > [<00000000b4383b46>] __napi_build_skb+0x15/0x50 > [<000000004902d9a0>] __napi_alloc_skb+0x26e/0x540 > [<00000000f9542b96>] napi_get_frags+0x59/0x140 > [<0000000002214936>] napi_get_frags_check+0x23/0xa0 > [<00000000c9a8df5a>] netif_napi_add_weight+0x443/0x910 > [<000000008f3a2156>] gro_cells_init+0x13f/0x230 > [<000000006f5f87fd>] vxlan_init+0x125/0x210 [vxlan] > [<00000000f9d7479b>] register_netdevice+0x271/0xeb0 > [<000000003eb98c8e>] __vxlan_dev_create+0x2f2/0x780 [vxlan] > [<00000000c5cdebe0>] vxlan_newlink+0xa0/0xf0 [vxlan] > [<000000004a0b0607>] __rtnl_newlink+0xcae/0x1490 > [<0000000037188a06>] rtnl_newlink+0x5f/0x90 > [<00000000b2d4e2b2>] rtnetlink_rcv_msg+0x31a/0x980 > [<00000000613a7411>] netlink_rcv_skb+0x120/0x380 > [<00000000836c6e0e>] netlink_unicast+0x439/0x660 > > The root case here is: > napi_get_frags_check() > napi_get_frags() > napi_alloc_skb() > __alloc_skb() <-- with flag SKB_ALLOC_NAPI > napi_skb_cache_get() > ... > napi_free_frags() > kfree_skb() > __kfree_skb() > > In function napi_get_frags(), the skb is alloced by napi_skb_cache_get(). > So, the skb should use __kfree_skb_defer (which called > napi_skb_cache_put()) to free. > To fix, add the function napi_free_frags_defer() to use __kfree_skb_defer > to free skb. > > Fixes: cfb8ec659521 ("skbuff: allow to use NAPI cache from __napi_alloc_skb()") > Signed-off-by: Wang Yufen <wangyufen@huawei.com> > --- > include/linux/netdevice.h | 8 ++++++++ > net/core/skbuff.c | 3 ++- > 2 files changed, 10 insertions(+), 1 deletion(-) > > diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h > index eddf8ee..0811663 100644 > --- a/include/linux/netdevice.h > +++ b/include/linux/netdevice.h > @@ -3833,6 +3833,14 @@ static inline void napi_free_frags(struct napi_struct *napi) > napi->skb = NULL; > } > > +static inline void napi_free_frags_defer(struct napi_struct *napi) > +{ > + if (!skb_unref(napi->skb)) > + return; > + __kfree_skb_defer(napi->skb); > + napi->skb = NULL; > +} > + > bool netdev_is_rx_handler_busy(struct net_device *dev); > int netdev_rx_handler_register(struct net_device *dev, > rx_handler_func_t *rx_handler, > diff --git a/net/core/skbuff.c b/net/core/skbuff.c > index d1a3fa6..1db3634 100644 > --- a/net/core/skbuff.c > +++ b/net/core/skbuff.c > @@ -214,7 +214,7 @@ void napi_get_frags_check(struct napi_struct *napi) > local_bh_disable(); > skb = napi_get_frags(napi); > WARN_ON_ONCE(!NAPI_HAS_SMALL_PAGE_FRAG && skb && skb->head_frag); > - napi_free_frags(napi); > + napi_free_frags_defer(napi); > local_bh_enable(); > } > > @@ -1073,6 +1073,7 @@ void __kfree_skb_defer(struct sk_buff *skb) > skb_release_all(skb); > napi_skb_cache_put(skb); > } > +EXPORT_SYMBOL(__kfree_skb_defer); > > void napi_skb_free_stolen_head(struct sk_buff *skb) > {
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index eddf8ee..0811663 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -3833,6 +3833,14 @@ static inline void napi_free_frags(struct napi_struct *napi) napi->skb = NULL; } +static inline void napi_free_frags_defer(struct napi_struct *napi) +{ + if (!skb_unref(napi->skb)) + return; + __kfree_skb_defer(napi->skb); + napi->skb = NULL; +} + bool netdev_is_rx_handler_busy(struct net_device *dev); int netdev_rx_handler_register(struct net_device *dev, rx_handler_func_t *rx_handler, diff --git a/net/core/skbuff.c b/net/core/skbuff.c index d1a3fa6..1db3634 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -214,7 +214,7 @@ void napi_get_frags_check(struct napi_struct *napi) local_bh_disable(); skb = napi_get_frags(napi); WARN_ON_ONCE(!NAPI_HAS_SMALL_PAGE_FRAG && skb && skb->head_frag); - napi_free_frags(napi); + napi_free_frags_defer(napi); local_bh_enable(); } @@ -1073,6 +1073,7 @@ void __kfree_skb_defer(struct sk_buff *skb) skb_release_all(skb); napi_skb_cache_put(skb); } +EXPORT_SYMBOL(__kfree_skb_defer); void napi_skb_free_stolen_head(struct sk_buff *skb) {
kmemleak reports this issue: unreferenced object 0xffff88819b8c97c0 (size 232): comm "ip", pid 2915, jiffies 4295153830 (age 408.877s) hex dump (first 32 bytes): 00 80 8c 9b 81 88 ff ff e0 24 f7 12 81 88 ff ff .........$...... 00 40 05 c0 81 88 ff ff 00 00 00 00 00 00 00 00 .@.............. backtrace: [<0000000009fc179a>] napi_skb_cache_get+0xd4/0x150 [<00000000b4383b46>] __napi_build_skb+0x15/0x50 [<000000004902d9a0>] __napi_alloc_skb+0x26e/0x540 [<00000000f9542b96>] napi_get_frags+0x59/0x140 [<0000000002214936>] napi_get_frags_check+0x23/0xa0 [<00000000c9a8df5a>] netif_napi_add_weight+0x443/0x910 [<000000008f3a2156>] gro_cells_init+0x13f/0x230 [<000000006f5f87fd>] vxlan_init+0x125/0x210 [vxlan] [<00000000f9d7479b>] register_netdevice+0x271/0xeb0 [<000000003eb98c8e>] __vxlan_dev_create+0x2f2/0x780 [vxlan] [<00000000c5cdebe0>] vxlan_newlink+0xa0/0xf0 [vxlan] [<000000004a0b0607>] __rtnl_newlink+0xcae/0x1490 [<0000000037188a06>] rtnl_newlink+0x5f/0x90 [<00000000b2d4e2b2>] rtnetlink_rcv_msg+0x31a/0x980 [<00000000613a7411>] netlink_rcv_skb+0x120/0x380 [<00000000836c6e0e>] netlink_unicast+0x439/0x660 The root case here is: napi_get_frags_check() napi_get_frags() napi_alloc_skb() __alloc_skb() <-- with flag SKB_ALLOC_NAPI napi_skb_cache_get() ... napi_free_frags() kfree_skb() __kfree_skb() In function napi_get_frags(), the skb is alloced by napi_skb_cache_get(). So, the skb should use __kfree_skb_defer (which called napi_skb_cache_put()) to free. To fix, add the function napi_free_frags_defer() to use __kfree_skb_defer to free skb. Fixes: cfb8ec659521 ("skbuff: allow to use NAPI cache from __napi_alloc_skb()") Signed-off-by: Wang Yufen <wangyufen@huawei.com> --- include/linux/netdevice.h | 8 ++++++++ net/core/skbuff.c | 3 ++- 2 files changed, 10 insertions(+), 1 deletion(-)