| 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-2024-50100: USB: gadget: dummy-hcd: Fix "task hung" problem |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| USB: gadget: dummy-hcd: Fix "task hung" problem |
| |
| The syzbot fuzzer has been encountering "task hung" problems ever |
| since the dummy-hcd driver was changed to use hrtimers instead of |
| regular timers. It turns out that the problems are caused by a subtle |
| difference between the timer_pending() and hrtimer_active() APIs. |
| |
| The changeover blindly replaced the first by the second. However, |
| timer_pending() returns True when the timer is queued but not when its |
| callback is running, whereas hrtimer_active() returns True when the |
| hrtimer is queued _or_ its callback is running. This difference |
| occasionally caused dummy_urb_enqueue() to think that the callback |
| routine had not yet started when in fact it was almost finished. As a |
| result the hrtimer was not restarted, which made it impossible for the |
| driver to dequeue later the URB that was just enqueued. This caused |
| usb_kill_urb() to hang, and things got worse from there. |
| |
| Since hrtimers have no API for telling when they are queued and the |
| callback isn't running, the driver must keep track of this for itself. |
| That's what this patch does, adding a new "timer_pending" flag and |
| setting or clearing it at the appropriate times. |
| |
| The Linux kernel CVE team has assigned CVE-2024-50100 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 6.10 with commit a7f3813e589fd8e2834720829a47b5eb914a9afe and fixed in 6.11.5 with commit f828205ee3e4ddc712a13fba6c9902d51e91ddaf |
| Issue introduced in 6.10 with commit a7f3813e589fd8e2834720829a47b5eb914a9afe and fixed in 6.12 with commit 5189df7b8088268012882c220d6aca4e64981348 |
| |
| 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-2024-50100 |
| 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/udc/dummy_hcd.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/cf7ee2291da551fc4b109fda1f6a332cb8212065 |
| https://git.kernel.org/stable/c/7d85884576a3be3616c260fc1fa862a59579d1ab |
| https://git.kernel.org/stable/c/f828205ee3e4ddc712a13fba6c9902d51e91ddaf |
| https://git.kernel.org/stable/c/5189df7b8088268012882c220d6aca4e64981348 |
