| From bippy-1.2.0 Mon Sep 17 00:00:00 2001 |
| From: Greg Kroah-Hartman <gregkh@kernel.org> |
| To: <linux-cve-announce@vger.kernel.org> |
| Reply-to: <cve@kernel.org>, <linux-kernel@vger.kernel.org> |
| Subject: CVE-2023-52733: s390/decompressor: specify __decompress() buf len to avoid overflow |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| s390/decompressor: specify __decompress() buf len to avoid overflow |
| |
| Historically calls to __decompress() didn't specify "out_len" parameter |
| on many architectures including s390, expecting that no writes beyond |
| uncompressed kernel image are performed. This has changed since commit |
| 2aa14b1ab2c4 ("zstd: import usptream v1.5.2") which includes zstd library |
| commit 6a7ede3dfccb ("Reduce size of dctx by reutilizing dst buffer |
| (#2751)"). Now zstd decompression code might store literal buffer in |
| the unwritten portion of the destination buffer. Since "out_len" is |
| not set, it is considered to be unlimited and hence free to use for |
| optimization needs. On s390 this might corrupt initrd or ipl report |
| which are often placed right after the decompressor buffer. Luckily the |
| size of uncompressed kernel image is already known to the decompressor, |
| so to avoid the problem simply specify it in the "out_len" parameter. |
| |
| The Linux kernel CVE team has assigned CVE-2023-52733 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 6.2 with commit 2aa14b1ab2c41a4fe41efae80d58bb77da91f19f and fixed in 5.4.232 with commit 16409f7d9ca5bb8220e1049ea9aae0d3c94d2dfb |
| Issue introduced in 6.2 with commit 2aa14b1ab2c41a4fe41efae80d58bb77da91f19f and fixed in 5.10.169 with commit 55dbd6f4ea954751340f4f73d5dcd7c8f12208b2 |
| Issue introduced in 6.2 with commit 2aa14b1ab2c41a4fe41efae80d58bb77da91f19f and fixed in 5.15.95 with commit 9ed522143f959630f8b7782ddc212900d8f609a9 |
| Issue introduced in 6.2 with commit 2aa14b1ab2c41a4fe41efae80d58bb77da91f19f and fixed in 6.1.13 with commit f1eb22d0ff064ad458b3b1a1eaa84ac3996206c2 |
| |
| 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-2023-52733 |
| 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: |
| arch/s390/boot/decompressor.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/16409f7d9ca5bb8220e1049ea9aae0d3c94d2dfb |
| https://git.kernel.org/stable/c/55dbd6f4ea954751340f4f73d5dcd7c8f12208b2 |
| https://git.kernel.org/stable/c/9ed522143f959630f8b7782ddc212900d8f609a9 |
| https://git.kernel.org/stable/c/f1eb22d0ff064ad458b3b1a1eaa84ac3996206c2 |
| https://git.kernel.org/stable/c/7ab41c2c08a32132ba8c14624910e2fe8ce4ba4b |
