| 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-2023-52497: erofs: fix lz4 inplace decompression |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| erofs: fix lz4 inplace decompression |
| |
| Currently EROFS can map another compressed buffer for inplace |
| decompression, that was used to handle the cases that some pages of |
| compressed data are actually not in-place I/O. |
| |
| However, like most simple LZ77 algorithms, LZ4 expects the compressed |
| data is arranged at the end of the decompressed buffer and it |
| explicitly uses memmove() to handle overlapping: |
| __________________________________________________________ |
| |_ direction of decompression --> ____ |_ compressed data _| |
| |
| Although EROFS arranges compressed data like this, it typically maps two |
| individual virtual buffers so the relative order is uncertain. |
| Previously, it was hardly observed since LZ4 only uses memmove() for |
| short overlapped literals and x86/arm64 memmove implementations seem to |
| completely cover it up and they don't have this issue. Juhyung reported |
| that EROFS data corruption can be found on a new Intel x86 processor. |
| After some analysis, it seems that recent x86 processors with the new |
| FSRM feature expose this issue with "rep movsb". |
| |
| Let's strictly use the decompressed buffer for lz4 inplace |
| decompression for now. Later, as an useful improvement, we could try |
| to tie up these two buffers together in the correct order. |
| |
| The Linux kernel CVE team has assigned CVE-2023-52497 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 5.3 with commit 0ffd71bcc3a03ebb3551661a36052488369c4de9 and fixed in 5.4.285 with commit 9ff2d260b25df6fe1341a79113d88fecf6bd553e |
| Issue introduced in 5.3 with commit 0ffd71bcc3a03ebb3551661a36052488369c4de9 and fixed in 5.10.211 with commit a0180e940cf1aefa7d516e20b259ad34f7a8b379 |
| Issue introduced in 5.3 with commit 0ffd71bcc3a03ebb3551661a36052488369c4de9 and fixed in 5.15.150 with commit 77cbc04a1a8610e303a0e0d74f2676667876a184 |
| Issue introduced in 5.3 with commit 0ffd71bcc3a03ebb3551661a36052488369c4de9 and fixed in 6.1.76 with commit 33bf23c9940dbd3a22aad7f0cda4c84ed5701847 |
| Issue introduced in 5.3 with commit 0ffd71bcc3a03ebb3551661a36052488369c4de9 and fixed in 6.6.15 with commit f36d200a80a3ca025532ed60dd1ac21b620e14ae |
| Issue introduced in 5.3 with commit 0ffd71bcc3a03ebb3551661a36052488369c4de9 and fixed in 6.7.3 with commit bffc4cc334c5bb31ded54bc3cfd651735a3cb79e |
| Issue introduced in 5.3 with commit 0ffd71bcc3a03ebb3551661a36052488369c4de9 and fixed in 6.8 with commit 3c12466b6b7bf1e56f9b32c366a3d83d87afb4de |
| |
| 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-2023-52497 |
| 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: |
| fs/erofs/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/9ff2d260b25df6fe1341a79113d88fecf6bd553e |
| https://git.kernel.org/stable/c/a0180e940cf1aefa7d516e20b259ad34f7a8b379 |
| https://git.kernel.org/stable/c/77cbc04a1a8610e303a0e0d74f2676667876a184 |
| https://git.kernel.org/stable/c/33bf23c9940dbd3a22aad7f0cda4c84ed5701847 |
| https://git.kernel.org/stable/c/f36d200a80a3ca025532ed60dd1ac21b620e14ae |
| https://git.kernel.org/stable/c/bffc4cc334c5bb31ded54bc3cfd651735a3cb79e |
| https://git.kernel.org/stable/c/3c12466b6b7bf1e56f9b32c366a3d83d87afb4de |
