| 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-2021-47617: PCI: pciehp: Fix infinite loop in IRQ handler upon power fault |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| PCI: pciehp: Fix infinite loop in IRQ handler upon power fault |
| |
| The Power Fault Detected bit in the Slot Status register differs from |
| all other hotplug events in that it is sticky: It can only be cleared |
| after turning off slot power. Per PCIe r5.0, sec. 6.7.1.8: |
| |
| If a power controller detects a main power fault on the hot-plug slot, |
| it must automatically set its internal main power fault latch [...]. |
| The main power fault latch is cleared when software turns off power to |
| the hot-plug slot. |
| |
| The stickiness used to cause interrupt storms and infinite loops which |
| were fixed in 2009 by commits 5651c48cfafe ("PCI pciehp: fix power fault |
| interrupt storm problem") and 99f0169c17f3 ("PCI: pciehp: enable |
| software notification on empty slots"). |
| |
| Unfortunately in 2020 the infinite loop issue was inadvertently |
| reintroduced by commit 8edf5332c393 ("PCI: pciehp: Fix MSI interrupt |
| race"): The hardirq handler pciehp_isr() clears the PFD bit until |
| pciehp's power_fault_detected flag is set. That happens in the IRQ |
| thread pciehp_ist(), which never learns of the event because the hardirq |
| handler is stuck in an infinite loop. Fix by setting the |
| power_fault_detected flag already in the hardirq handler. |
| |
| The Linux kernel CVE team has assigned CVE-2021-47617 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 4.19.149 with commit a8cc52270f3d8e8f4faf01ffd6c4a95bbfb55ba4 and fixed in 4.19.233 with commit ff27f7d0333cff89ec85c419f431aca1b38fb16a |
| Issue introduced in 5.4.69 with commit 4667358dab9cc07da044d5bc087065545b1000df and fixed in 5.4.177 with commit 464da38ba827f670deac6500a1de9a4f0f44c41d |
| Issue introduced in 5.7 with commit 8edf5332c39340b9583cf9cba659eb7ec71f75b5 and fixed in 5.10.97 with commit 3b4c966fb156ff3e70b2526d964952ff7c1574d9 |
| Issue introduced in 5.7 with commit 8edf5332c39340b9583cf9cba659eb7ec71f75b5 and fixed in 5.15.20 with commit 1db58c6584a72102e98af2e600ea184ddaf2b8af |
| Issue introduced in 5.7 with commit 8edf5332c39340b9583cf9cba659eb7ec71f75b5 and fixed in 5.16.6 with commit 6d6f1f0dac3e3441ecdb1103d4efb11b9ed24dd5 |
| Issue introduced in 5.7 with commit 8edf5332c39340b9583cf9cba659eb7ec71f75b5 and fixed in 5.17 with commit 23584c1ed3e15a6f4bfab8dc5a88d94ab929ee12 |
| |
| 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-2021-47617 |
| 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/pci/hotplug/pciehp_hpc.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/ff27f7d0333cff89ec85c419f431aca1b38fb16a |
| https://git.kernel.org/stable/c/464da38ba827f670deac6500a1de9a4f0f44c41d |
| https://git.kernel.org/stable/c/3b4c966fb156ff3e70b2526d964952ff7c1574d9 |
| https://git.kernel.org/stable/c/1db58c6584a72102e98af2e600ea184ddaf2b8af |
| https://git.kernel.org/stable/c/6d6f1f0dac3e3441ecdb1103d4efb11b9ed24dd5 |
| https://git.kernel.org/stable/c/23584c1ed3e15a6f4bfab8dc5a88d94ab929ee12 |
