| 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-2021-47561: i2c: virtio: disable timeout handling |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| i2c: virtio: disable timeout handling |
| |
| If a timeout is hit, it can result is incorrect data on the I2C bus |
| and/or memory corruptions in the guest since the device can still be |
| operating on the buffers it was given while the guest has freed them. |
| |
| Here is, for example, the start of a slub_debug splat which was |
| triggered on the next transfer after one transfer was forced to timeout |
| by setting a breakpoint in the backend (rust-vmm/vhost-device): |
| |
| BUG kmalloc-1k (Not tainted): Poison overwritten |
| First byte 0x1 instead of 0x6b |
| Allocated in virtio_i2c_xfer+0x65/0x35c age=350 cpu=0 pid=29 |
| __kmalloc+0xc2/0x1c9 |
| virtio_i2c_xfer+0x65/0x35c |
| __i2c_transfer+0x429/0x57d |
| i2c_transfer+0x115/0x134 |
| i2cdev_ioctl_rdwr+0x16a/0x1de |
| i2cdev_ioctl+0x247/0x2ed |
| vfs_ioctl+0x21/0x30 |
| sys_ioctl+0xb18/0xb41 |
| Freed in virtio_i2c_xfer+0x32e/0x35c age=244 cpu=0 pid=29 |
| kfree+0x1bd/0x1cc |
| virtio_i2c_xfer+0x32e/0x35c |
| __i2c_transfer+0x429/0x57d |
| i2c_transfer+0x115/0x134 |
| i2cdev_ioctl_rdwr+0x16a/0x1de |
| i2cdev_ioctl+0x247/0x2ed |
| vfs_ioctl+0x21/0x30 |
| sys_ioctl+0xb18/0xb41 |
| |
| There is no simple fix for this (the driver would have to always create |
| bounce buffers and hold on to them until the device eventually returns |
| the buffers), so just disable the timeout support for now. |
| |
| The Linux kernel CVE team has assigned CVE-2021-47561 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 5.15 with commit 3cfc88380413d20f777dc6648a38f683962e52bf and fixed in 5.15.6 with commit cc432b0727ce404cc13e8f6b5ce29f412c3f9f1f |
| Issue introduced in 5.15 with commit 3cfc88380413d20f777dc6648a38f683962e52bf and fixed in 5.16 with commit 84e1d0bf1d7121759622dabf8fbef4c99ad597c5 |
| |
| 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-2021-47561 |
| 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/i2c/busses/i2c-virtio.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/cc432b0727ce404cc13e8f6b5ce29f412c3f9f1f |
| https://git.kernel.org/stable/c/84e1d0bf1d7121759622dabf8fbef4c99ad597c5 |
