| From 12fd148b9e54b095dcf0338d501d8d8f62a6e7e9 Mon Sep 17 00:00:00 2001 |
| From: Sasha Levin <sashal@kernel.org> |
| Date: Sat, 10 Jul 2021 11:16:35 +0800 |
| Subject: xdp, net: Fix use-after-free in bpf_xdp_link_release |
| |
| From: Xuan Zhuo <xuanzhuo@linux.alibaba.com> |
| |
| [ Upstream commit 5acc7d3e8d342858405fbbc671221f676b547ce7 ] |
| |
| The problem occurs between dev_get_by_index() and dev_xdp_attach_link(). |
| At this point, dev_xdp_uninstall() is called. Then xdp link will not be |
| detached automatically when dev is released. But link->dev already |
| points to dev, when xdp link is released, dev will still be accessed, |
| but dev has been released. |
| |
| dev_get_by_index() | |
| link->dev = dev | |
| | rtnl_lock() |
| | unregister_netdevice_many() |
| | dev_xdp_uninstall() |
| | rtnl_unlock() |
| rtnl_lock(); | |
| dev_xdp_attach_link() | |
| rtnl_unlock(); | |
| | netdev_run_todo() // dev released |
| bpf_xdp_link_release() | |
| /* access dev. | |
| use-after-free */ | |
| |
| [ 45.966867] BUG: KASAN: use-after-free in bpf_xdp_link_release+0x3b8/0x3d0 |
| [ 45.967619] Read of size 8 at addr ffff00000f9980c8 by task a.out/732 |
| [ 45.968297] |
| [ 45.968502] CPU: 1 PID: 732 Comm: a.out Not tainted 5.13.0+ #22 |
| [ 45.969222] Hardware name: linux,dummy-virt (DT) |
| [ 45.969795] Call trace: |
| [ 45.970106] dump_backtrace+0x0/0x4c8 |
| [ 45.970564] show_stack+0x30/0x40 |
| [ 45.970981] dump_stack_lvl+0x120/0x18c |
| [ 45.971470] print_address_description.constprop.0+0x74/0x30c |
| [ 45.972182] kasan_report+0x1e8/0x200 |
| [ 45.972659] __asan_report_load8_noabort+0x2c/0x50 |
| [ 45.973273] bpf_xdp_link_release+0x3b8/0x3d0 |
| [ 45.973834] bpf_link_free+0xd0/0x188 |
| [ 45.974315] bpf_link_put+0x1d0/0x218 |
| [ 45.974790] bpf_link_release+0x3c/0x58 |
| [ 45.975291] __fput+0x20c/0x7e8 |
| [ 45.975706] ____fput+0x24/0x30 |
| [ 45.976117] task_work_run+0x104/0x258 |
| [ 45.976609] do_notify_resume+0x894/0xaf8 |
| [ 45.977121] work_pending+0xc/0x328 |
| [ 45.977575] |
| [ 45.977775] The buggy address belongs to the page: |
| [ 45.978369] page:fffffc00003e6600 refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x4f998 |
| [ 45.979522] flags: 0x7fffe0000000000(node=0|zone=0|lastcpupid=0x3ffff) |
| [ 45.980349] raw: 07fffe0000000000 fffffc00003e6708 ffff0000dac3c010 0000000000000000 |
| [ 45.981309] raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000 |
| [ 45.982259] page dumped because: kasan: bad access detected |
| [ 45.982948] |
| [ 45.983153] Memory state around the buggy address: |
| [ 45.983753] ffff00000f997f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc |
| [ 45.984645] ffff00000f998000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff |
| [ 45.985533] >ffff00000f998080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff |
| [ 45.986419] ^ |
| [ 45.987112] ffff00000f998100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff |
| [ 45.988006] ffff00000f998180: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff |
| [ 45.988895] ================================================================== |
| [ 45.989773] Disabling lock debugging due to kernel taint |
| [ 45.990552] Kernel panic - not syncing: panic_on_warn set ... |
| [ 45.991166] CPU: 1 PID: 732 Comm: a.out Tainted: G B 5.13.0+ #22 |
| [ 45.991929] Hardware name: linux,dummy-virt (DT) |
| [ 45.992448] Call trace: |
| [ 45.992753] dump_backtrace+0x0/0x4c8 |
| [ 45.993208] show_stack+0x30/0x40 |
| [ 45.993627] dump_stack_lvl+0x120/0x18c |
| [ 45.994113] dump_stack+0x1c/0x34 |
| [ 45.994530] panic+0x3a4/0x7d8 |
| [ 45.994930] end_report+0x194/0x198 |
| [ 45.995380] kasan_report+0x134/0x200 |
| [ 45.995850] __asan_report_load8_noabort+0x2c/0x50 |
| [ 45.996453] bpf_xdp_link_release+0x3b8/0x3d0 |
| [ 45.997007] bpf_link_free+0xd0/0x188 |
| [ 45.997474] bpf_link_put+0x1d0/0x218 |
| [ 45.997942] bpf_link_release+0x3c/0x58 |
| [ 45.998429] __fput+0x20c/0x7e8 |
| [ 45.998833] ____fput+0x24/0x30 |
| [ 45.999247] task_work_run+0x104/0x258 |
| [ 45.999731] do_notify_resume+0x894/0xaf8 |
| [ 46.000236] work_pending+0xc/0x328 |
| [ 46.000697] SMP: stopping secondary CPUs |
| [ 46.001226] Dumping ftrace buffer: |
| [ 46.001663] (ftrace buffer empty) |
| [ 46.002110] Kernel Offset: disabled |
| [ 46.002545] CPU features: 0x00000001,23202c00 |
| [ 46.003080] Memory Limit: none |
| |
| Fixes: aa8d3a716b59db6c ("bpf, xdp: Add bpf_link-based XDP attachment API") |
| Reported-by: Abaci <abaci@linux.alibaba.com> |
| Signed-off-by: Xuan Zhuo <xuanzhuo@linux.alibaba.com> |
| Signed-off-by: Alexei Starovoitov <ast@kernel.org> |
| Reviewed-by: Dust Li <dust.li@linux.alibaba.com> |
| Acked-by: Andrii Nakryiko <andrii@kernel.org> |
| Link: https://lore.kernel.org/bpf/20210710031635.41649-1-xuanzhuo@linux.alibaba.com |
| Signed-off-by: Sasha Levin <sashal@kernel.org> |
| --- |
| net/core/dev.c | 14 ++++++++++---- |
| 1 file changed, 10 insertions(+), 4 deletions(-) |
| |
| diff --git a/net/core/dev.c b/net/core/dev.c |
| index 4f29dde4ed0a..0dcedcdf6d7e 100644 |
| --- a/net/core/dev.c |
| +++ b/net/core/dev.c |
| @@ -9659,14 +9659,17 @@ int bpf_xdp_link_attach(const union bpf_attr *attr, struct bpf_prog *prog) |
| struct net_device *dev; |
| int err, fd; |
| |
| + rtnl_lock(); |
| dev = dev_get_by_index(net, attr->link_create.target_ifindex); |
| - if (!dev) |
| + if (!dev) { |
| + rtnl_unlock(); |
| return -EINVAL; |
| + } |
| |
| link = kzalloc(sizeof(*link), GFP_USER); |
| if (!link) { |
| err = -ENOMEM; |
| - goto out_put_dev; |
| + goto unlock; |
| } |
| |
| bpf_link_init(&link->link, BPF_LINK_TYPE_XDP, &bpf_xdp_link_lops, prog); |
| @@ -9676,14 +9679,14 @@ int bpf_xdp_link_attach(const union bpf_attr *attr, struct bpf_prog *prog) |
| err = bpf_link_prime(&link->link, &link_primer); |
| if (err) { |
| kfree(link); |
| - goto out_put_dev; |
| + goto unlock; |
| } |
| |
| - rtnl_lock(); |
| err = dev_xdp_attach_link(dev, NULL, link); |
| rtnl_unlock(); |
| |
| if (err) { |
| + link->dev = NULL; |
| bpf_link_cleanup(&link_primer); |
| goto out_put_dev; |
| } |
| @@ -9693,6 +9696,9 @@ int bpf_xdp_link_attach(const union bpf_attr *attr, struct bpf_prog *prog) |
| dev_put(dev); |
| return fd; |
| |
| +unlock: |
| + rtnl_unlock(); |
| + |
| out_put_dev: |
| dev_put(dev); |
| return err; |
| -- |
| 2.30.2 |
| |