| 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-2021-47469: spi: Fix deadlock when adding SPI controllers on SPI buses |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| spi: Fix deadlock when adding SPI controllers on SPI buses |
| |
| Currently we have a global spi_add_lock which we take when adding new |
| devices so that we can check that we're not trying to reuse a chip |
| select that's already controlled. This means that if the SPI device is |
| itself a SPI controller and triggers the instantiation of further SPI |
| devices we trigger a deadlock as we try to register and instantiate |
| those devices while in the process of doing so for the parent controller |
| and hence already holding the global spi_add_lock. Since we only care |
| about concurrency within a single SPI bus move the lock to be per |
| controller, avoiding the deadlock. |
| |
| This can be easily triggered in the case of spi-mux. |
| |
| The Linux kernel CVE team has assigned CVE-2021-47469 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Fixed in 5.4.286 with commit aa3f3d7bef59583f2d3234173105a27ff61ef8fe |
| Fixed in 5.10.230 with commit c8dce228db6f81dbc897a018dfc5c418e917cf64 |
| Fixed in 5.14.15 with commit 722ef19a161ce3fffb3d1b01ce2301c306639bdd |
| Fixed in 5.15 with commit 6098475d4cb48d821bdf453c61118c56e26294f0 |
| |
| 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-2021-47469 |
| 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/spi/spi.c |
| include/linux/spi/spi.h |
| |
| |
| 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/aa3f3d7bef59583f2d3234173105a27ff61ef8fe |
| https://git.kernel.org/stable/c/c8dce228db6f81dbc897a018dfc5c418e917cf64 |
| https://git.kernel.org/stable/c/722ef19a161ce3fffb3d1b01ce2301c306639bdd |
| https://git.kernel.org/stable/c/6098475d4cb48d821bdf453c61118c56e26294f0 |
