| From bippy-5f407fcff5a0 Mon Sep 17 00:00:00 2001 |
| From: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| To: <linux-cve-announce@vger.kernel.org> |
| Reply-to: <cve@kernel.org>, <linux-kernel@vger.kernel.org> |
| Subject: CVE-2021-47299: xdp, net: Fix use-after-free in bpf_xdp_link_release |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| xdp, net: Fix use-after-free in bpf_xdp_link_release |
| |
| 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 |
| |
| The Linux kernel CVE team has assigned CVE-2021-47299 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 5.9 with commit aa8d3a716b59db6c1ad6c68fb8aa05e31980da60 and fixed in 5.10.54 with commit ca9ba1de8f09976b45ccc8e655c51c6201992139 |
| Issue introduced in 5.9 with commit aa8d3a716b59db6c1ad6c68fb8aa05e31980da60 and fixed in 5.13.6 with commit a7537dc73e69ad9c0b67ad24ad3ebee954ed0af6 |
| Issue introduced in 5.9 with commit aa8d3a716b59db6c1ad6c68fb8aa05e31980da60 and fixed in 5.14 with commit 5acc7d3e8d342858405fbbc671221f676b547ce7 |
| |
| Please see https://www.kernel.org for a full list of currently supported |
| kernel versions by the kernel community. |
| |
| Unaffected versions might change over time as fixes are backported to |
| older supported kernel versions. The official CVE entry at |
| https://cve.org/CVERecord/?id=CVE-2021-47299 |
| will be updated if fixes are backported, please check that for the most |
| up to date information about this issue. |
| |
| |
| Affected files |
| ============== |
| |
| The file(s) affected by this issue are: |
| net/core/dev.c |
| |
| |
| Mitigation |
| ========== |
| |
| The Linux kernel CVE team recommends that you update to the latest |
| stable kernel version for this, and many other bugfixes. Individual |
| changes are never tested alone, but rather are part of a larger kernel |
| release. Cherry-picking individual commits is not recommended or |
| supported by the Linux kernel community at all. If however, updating to |
| the latest release is impossible, the individual changes to resolve this |
| issue can be found at these commits: |
| https://git.kernel.org/stable/c/ca9ba1de8f09976b45ccc8e655c51c6201992139 |
| https://git.kernel.org/stable/c/a7537dc73e69ad9c0b67ad24ad3ebee954ed0af6 |
| https://git.kernel.org/stable/c/5acc7d3e8d342858405fbbc671221f676b547ce7 |
