| From bippy-1.1.0 Mon Sep 17 00:00:00 2001 |
| From: Greg Kroah-Hartman <gregkh@kernel.org> |
| To: <linux-cve-announce@vger.kernel.org> |
| Reply-to: <cve@kernel.org>, <linux-kernel@vger.kernel.org> |
| Subject: CVE-2023-53045: usb: gadget: u_audio: don't let userspace block driver unbind |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| usb: gadget: u_audio: don't let userspace block driver unbind |
| |
| In the unbind callback for f_uac1 and f_uac2, a call to snd_card_free() |
| via g_audio_cleanup() will disconnect the card and then wait for all |
| resources to be released, which happens when the refcount falls to zero. |
| Since userspace can keep the refcount incremented by not closing the |
| relevant file descriptor, the call to unbind may block indefinitely. |
| This can cause a deadlock during reboot, as evidenced by the following |
| blocked task observed on my machine: |
| |
| task:reboot state:D stack:0 pid:2827 ppid:569 flags:0x0000000c |
| Call trace: |
| __switch_to+0xc8/0x140 |
| __schedule+0x2f0/0x7c0 |
| schedule+0x60/0xd0 |
| schedule_timeout+0x180/0x1d4 |
| wait_for_completion+0x78/0x180 |
| snd_card_free+0x90/0xa0 |
| g_audio_cleanup+0x2c/0x64 |
| afunc_unbind+0x28/0x60 |
| ... |
| kernel_restart+0x4c/0xac |
| __do_sys_reboot+0xcc/0x1ec |
| __arm64_sys_reboot+0x28/0x30 |
| invoke_syscall+0x4c/0x110 |
| ... |
| |
| The issue can also be observed by opening the card with arecord and |
| then stopping the process through the shell before unbinding: |
| |
| # arecord -D hw:UAC2Gadget -f S32_LE -c 2 -r 48000 /dev/null |
| Recording WAVE '/dev/null' : Signed 32 bit Little Endian, Rate 48000 Hz, Stereo |
| ^Z[1]+ Stopped arecord -D hw:UAC2Gadget -f S32_LE -c 2 -r 48000 /dev/null |
| # echo gadget.0 > /sys/bus/gadget/drivers/configfs-gadget/unbind |
| (observe that the unbind command never finishes) |
| |
| Fix the problem by using snd_card_free_when_closed() instead, which will |
| still disconnect the card as desired, but defer the task of freeing the |
| resources to the core once userspace closes its file descriptor. |
| |
| The Linux kernel CVE team has assigned CVE-2023-53045 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 3.4 with commit 132fcb460839a876f5bc8b71bede60f8d0875757 and fixed in 4.14.312 with commit 3e016ef2e72da93a2ea7afbb45de1b481b44d761 |
| Issue introduced in 3.4 with commit 132fcb460839a876f5bc8b71bede60f8d0875757 and fixed in 4.19.280 with commit 3256e152b645fc1e788ba44c2d8ced690113e3e6 |
| Issue introduced in 3.4 with commit 132fcb460839a876f5bc8b71bede60f8d0875757 and fixed in 5.4.240 with commit 0eda2004f38d95ef5715d62be884cd344260535b |
| Issue introduced in 3.4 with commit 132fcb460839a876f5bc8b71bede60f8d0875757 and fixed in 5.10.177 with commit 33f341c1fc60e172a3515c51bdabee11e83d1ee9 |
| Issue introduced in 3.4 with commit 132fcb460839a876f5bc8b71bede60f8d0875757 and fixed in 5.15.105 with commit b131989797f7287d7fdadb2bababc05a15d44750 |
| Issue introduced in 3.4 with commit 132fcb460839a876f5bc8b71bede60f8d0875757 and fixed in 6.1.22 with commit 3bc7324e4911351e39c54a62e6ca46321cb10faf |
| Issue introduced in 3.4 with commit 132fcb460839a876f5bc8b71bede60f8d0875757 and fixed in 6.2.9 with commit 43ca70753dfffd517d2af126da28690f8f615605 |
| Issue introduced in 3.4 with commit 132fcb460839a876f5bc8b71bede60f8d0875757 and fixed in 6.3 with commit 6c67ed9ad9b83e453e808f9b31a931a20a25629b |
| |
| 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-2023-53045 |
| 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: |
| drivers/usb/gadget/function/u_audio.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/3e016ef2e72da93a2ea7afbb45de1b481b44d761 |
| https://git.kernel.org/stable/c/3256e152b645fc1e788ba44c2d8ced690113e3e6 |
| https://git.kernel.org/stable/c/0eda2004f38d95ef5715d62be884cd344260535b |
| https://git.kernel.org/stable/c/33f341c1fc60e172a3515c51bdabee11e83d1ee9 |
| https://git.kernel.org/stable/c/b131989797f7287d7fdadb2bababc05a15d44750 |
| https://git.kernel.org/stable/c/3bc7324e4911351e39c54a62e6ca46321cb10faf |
| https://git.kernel.org/stable/c/43ca70753dfffd517d2af126da28690f8f615605 |
| https://git.kernel.org/stable/c/6c67ed9ad9b83e453e808f9b31a931a20a25629b |
