<div dir="ltr">Looks correct.<div>Could you, please, also change the order of `list_del` and `kni_dev_remove` in `kni_release`? It suffers from the same problem.</div><div> </div><div>Igor</div></div> <div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Fri, Jan 28, 2022 at 5:43 AM Min Hu (Connor) <<a href="mailto:humin29@huawei.com">humin29@huawei.com</a>> wrote: </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-style:solid;border-left-color:rgb(204,204,204);padding-left:1ex">From: Huisong Li <<a href="mailto:lihuisong@huawei.com" target="_blank">lihuisong@huawei.com</a>> The "kni_dev" is the private data of the "net_device" in kni, and allocated with the "net_device" by calling "alloc_netdev()". The "net_device" is freed by calling "free_netdev()" when kni release. The freed memory includes the "kni_dev". So After "kni_dev" should not be accessed after "net_device" is released. Fixes: e77fec694936 ("kni: fix possible mbuf leaks and speed up port release") Cc: <a href="mailto:stable@dpdk.org" target="_blank">stable@dpdk.org</a> KASAN trace: [ 85.263717] ========================================================== [ 85.264418] BUG: KASAN: use-after-free in kni_net_release_fifo_phy+ 0x30/0x84 [rte_kni] [ 85.265139] Read of size 8 at addr ffff000260668d60 by task kni/341 [ 85.265703] [ 85.265857] CPU: 0 PID: 341 Comm: kni Tainted: G U O 5.15.0-rc4+ #1 [ 85.266525] Hardware name: linux,dummy-virt (DT) [ 85.266968] Call trace: [ 85.267220] dump_backtrace+0x0/0x2d0 [ 85.267591] show_stack+0x24/0x30 [ 85.267924] dump_stack_lvl+0x8c/0xb8 [ 85.268294] print_address_description.constprop.0+0x74/0x2b8 [ 85.268855] kasan_report+0x1e4/0x200 [ 85.269224] __asan_load8+0x98/0xd4 [ 85.269577] kni_net_release_fifo_phy+0x30/0x84 [rte_kni] [ 85.270116] kni_dev_remove.isra.0+0x50/0x64 [rte_kni] [ 85.270630] kni_ioctl_release+0x254/0x320 [rte_kni] [ 85.271136] kni_ioctl+0x64/0xb0 [rte_kni] [ 85.271553] __arm64_sys_ioctl+0xdc/0x120 [ 85.271955] invoke_syscall+0x68/0x1a0 [ 85.272332] el0_svc_common.constprop.0+0x90/0x200 [ 85.272807] do_el0_svc+0x94/0xa4 [ 85.273144] el0_svc+0x78/0x240 [ 85.273463] el0t_64_sync_handler+0x1a8/0x1b0 [ 85.273895] el0t_64_sync+0x1a0/0x1a4 [ 85.274264] [ 85.274427] Allocated by task 341: [ 85.274767] kasan_save_stack+0x2c/0x60 [ 85.275157] __kasan_kmalloc+0x90/0xb4 [ 85.275533] __kmalloc_node+0x230/0x594 [ 85.275917] kvmalloc_node+0x8c/0x190 [ 85.276286] alloc_netdev_mqs+0x70/0x6b0 [ 85.276678] kni_ioctl_create+0x224/0xf40 [rte_kni] [ 85.277166] kni_ioctl+0x9c/0xb0 [rte_kni] [ 85.277581] __arm64_sys_ioctl+0xdc/0x120 [ 85.277980] invoke_syscall+0x68/0x1a0 [ 85.278357] el0_svc_common.constprop.0+0x90/0x200 [ 85.278830] do_el0_svc+0x94/0xa4 [ 85.279172] el0_svc+0x78/0x240 [ 85.279491] el0t_64_sync_handler+0x1a8/0x1b0 [ 85.279925] el0t_64_sync+0x1a0/0x1a4 [ 85.280292] [ 85.280454] Freed by task 341: [ 85.280763] kasan_save_stack+0x2c/0x60 [ 85.281147] kasan_set_track+0x2c/0x40 [ 85.281522] kasan_set_free_info+0x2c/0x50 [ 85.281930] __kasan_slab_free+0xdc/0x140 [ 85.282331] slab_free_freelist_hook+0x90/0x250 [ 85.282782] kfree+0x128/0x580 [ 85.283099] kvfree+0x48/0x60 [ 85.283402] netdev_freemem+0x34/0x44 [ 85.283770] netdev_release+0x50/0x64 [ 85.284138] device_release+0xa0/0x120 [ 85.284516] kobject_put+0xf8/0x160 [ 85.284867] put_device+0x20/0x30 [ 85.285204] free_netdev+0x22c/0x310 [ 85.285562] kni_dev_remove.isra.0+0x48/0x64 [rte_kni] [ 85.286076] kni_ioctl_release+0x254/0x320 [rte_kni] [ 85.286573] kni_ioctl+0x64/0xb0 [rte_kni] [ 85.286992] __arm64_sys_ioctl+0xdc/0x120 [ 85.287392] invoke_syscall+0x68/0x1a0 [ 85.287769] el0_svc_common.constprop.0+0x90/0x200 [ 85.288243] do_el0_svc+0x94/0xa4 [ 85.288579] el0_svc+0x78/0x240 [ 85.288899] el0t_64_sync_handler+0x1a8/0x1b0 [ 85.289332] el0t_64_sync+0x1a0/0x1a4 [ 85.289699] [ 85.289862] The buggy address belongs to the object at ffff000260668000 [ 85.289862] which belongs to the cache kmalloc-cg-8k of size 8192 [ 85.291079] The buggy address is located 3424 bytes inside of [ 85.291079] 8192-byte region [ffff000260668000, ffff00026066a000) [ 85.292213] The buggy address belongs to the page: [ 85.292684] page:(____ptrval____) refcount:1 mapcount:0 mapping: 0000000000000000 index:0x0 pfn:0x2a0668 [ 85.293585] head:(____ptrval____) order:3 compound_mapcount:0 compound_pincount:0 [ 85.294305] flags: 0xbfff80000010200(slab|head|node=0|zone=2| lastcpupid=0x7fff) [ 85.295020] raw: 0bfff80000010200 0000000000000000 dead000000000122 ffff0000c000d680 [ 85.295767] raw: 0000000000000000 0000000080020002 00000001ffffffff 0000000000000000 [ 85.296512] page dumped because: kasan: bad access detected [ 85.297054] [ 85.297217] Memory state around the buggy address: [ 85.297688] ffff000260668c00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 85.298384] ffff000260668c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 85.299088] >ffff000260668d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 85.299781] ^ [ 85.300396] ffff000260668d80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 85.301092] ffff000260668e00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb [ 85.301787] =========================================================== Signed-off-by: Huisong Li <<a href="mailto:lihuisong@huawei.com" target="_blank">lihuisong@huawei.com</a>> Signed-off-by: Min Hu (Connor) <<a href="mailto:humin29@huawei.com" target="_blank">humin29@huawei.com</a>> --- kernel/linux/kni/kni_misc.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/kernel/linux/kni/kni_misc.c b/kernel/linux/kni/kni_misc.c index f10dcd069d..b3684c4fa6 100644 --- a/kernel/linux/kni/kni_misc.c +++ b/kernel/linux/kni/kni_misc.c @@ -184,13 +184,17 @@ kni_dev_remove(struct kni_dev *dev) if (!dev) return -ENODEV; + /* + * The memory of kni device is allocated and released together + * with net device. Release mbuf before freeing net device. + */ + kni_net_release_fifo_phy(dev); + if (dev->net_dev) { unregister_netdev(dev->net_dev); free_netdev(dev->net_dev); } - kni_net_release_fifo_phy(dev); - return 0; } @@ -470,8 +474,8 @@ kni_ioctl_release(struct net *net, uint32_t ioctl_num, dev->pthread = NULL; } - kni_dev_remove(dev); list_del(&dev->list); + kni_dev_remove(dev); ret = 0; break; } -- 2.33.0 </blockquote></div>