| 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-2021-47383: tty: Fix out-of-bound vmalloc access in imageblit |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| tty: Fix out-of-bound vmalloc access in imageblit |
| |
| This issue happens when a userspace program does an ioctl |
| FBIOPUT_VSCREENINFO passing the fb_var_screeninfo struct |
| containing only the fields xres, yres, and bits_per_pixel |
| with values. |
| |
| If this struct is the same as the previous ioctl, the |
| vc_resize() detects it and doesn't call the resize_screen(), |
| leaving the fb_var_screeninfo incomplete. And this leads to |
| the updatescrollmode() calculates a wrong value to |
| fbcon_display->vrows, which makes the real_y() return a |
| wrong value of y, and that value, eventually, causes |
| the imageblit to access an out-of-bound address value. |
| |
| To solve this issue I made the resize_screen() be called |
| even if the screen does not need any resizing, so it will |
| "fix and fill" the fb_var_screeninfo independently. |
| |
| The Linux kernel CVE team has assigned CVE-2021-47383 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Fixed in 4.4.286 with commit 7e71fcedfda6f7de18f850a6b36e78d78b04476f |
| Fixed in 4.9.285 with commit 70aed03b1d5a5df974f456cdc8eedb213c94bb8b |
| Fixed in 4.14.249 with commit 067c694d06040db6f0c65281bb358452ca6d85b9 |
| Fixed in 4.19.209 with commit 8a6a240f52e14356386030d8958ae8b1761d2325 |
| Fixed in 5.4.151 with commit 883f7897a25e3ce14a7f274ca4c73f49ac84002a |
| Fixed in 5.10.71 with commit d570c48dd37dbe8fc6875d4461d01a9554ae2560 |
| Fixed in 5.14.10 with commit 699d926585daa6ec44be556cdc1ab89e5d54557b |
| Fixed in 5.15 with commit 3b0c406124719b625b1aba431659f5cdc24a982c |
| |
| 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-2021-47383 |
| 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/tty/vt/vt.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/7e71fcedfda6f7de18f850a6b36e78d78b04476f |
| https://git.kernel.org/stable/c/70aed03b1d5a5df974f456cdc8eedb213c94bb8b |
| https://git.kernel.org/stable/c/067c694d06040db6f0c65281bb358452ca6d85b9 |
| https://git.kernel.org/stable/c/8a6a240f52e14356386030d8958ae8b1761d2325 |
| https://git.kernel.org/stable/c/883f7897a25e3ce14a7f274ca4c73f49ac84002a |
| https://git.kernel.org/stable/c/d570c48dd37dbe8fc6875d4461d01a9554ae2560 |
| https://git.kernel.org/stable/c/699d926585daa6ec44be556cdc1ab89e5d54557b |
| https://git.kernel.org/stable/c/3b0c406124719b625b1aba431659f5cdc24a982c |
