| 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-2022-49554: zsmalloc: fix races between asynchronous zspage free and page migration |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| zsmalloc: fix races between asynchronous zspage free and page migration |
| |
| The asynchronous zspage free worker tries to lock a zspage's entire page |
| list without defending against page migration. Since pages which haven't |
| yet been locked can concurrently migrate off the zspage page list while |
| lock_zspage() churns away, lock_zspage() can suffer from a few different |
| lethal races. |
| |
| It can lock a page which no longer belongs to the zspage and unsafely |
| dereference page_private(), it can unsafely dereference a torn pointer to |
| the next page (since there's a data race), and it can observe a spurious |
| NULL pointer to the next page and thus not lock all of the zspage's pages |
| (since a single page migration will reconstruct the entire page list, and |
| create_page_chain() unconditionally zeroes out each list pointer in the |
| process). |
| |
| Fix the races by using migrate_read_lock() in lock_zspage() to synchronize |
| with page migration. |
| |
| The Linux kernel CVE team has assigned CVE-2022-49554 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 4.14 with commit 77ff465799c60294e248000cd22ae8171da3304c and fixed in 4.14.282 with commit 3674d8a8dadd03a447dd21069d4dacfc3399b63b |
| Issue introduced in 4.14 with commit 77ff465799c60294e248000cd22ae8171da3304c and fixed in 4.19.246 with commit 645996efc2ae391246d595832aaa6f9d3cc338c7 |
| Issue introduced in 4.14 with commit 77ff465799c60294e248000cd22ae8171da3304c and fixed in 5.4.197 with commit fc658c083904427abbf8f18280d517ee2668677c |
| Issue introduced in 4.14 with commit 77ff465799c60294e248000cd22ae8171da3304c and fixed in 5.10.120 with commit fae05b2314b147a78fbed1dc4c645d9a66313758 |
| Issue introduced in 4.14 with commit 77ff465799c60294e248000cd22ae8171da3304c and fixed in 5.15.45 with commit 3ec459c8810e658401be428d3168eacfc380bdd0 |
| Issue introduced in 4.14 with commit 77ff465799c60294e248000cd22ae8171da3304c and fixed in 5.17.13 with commit 8ba7b7c1dad1f6503c541778f31b33f7f62eb966 |
| Issue introduced in 4.14 with commit 77ff465799c60294e248000cd22ae8171da3304c and fixed in 5.18.2 with commit c5402fb5f71f1a725f1e55d9c6799c0c7bec308f |
| Issue introduced in 4.14 with commit 77ff465799c60294e248000cd22ae8171da3304c and fixed in 5.19 with commit 2505a981114dcb715f8977b8433f7540854851d8 |
| |
| 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-2022-49554 |
| 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: |
| mm/zsmalloc.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/3674d8a8dadd03a447dd21069d4dacfc3399b63b |
| https://git.kernel.org/stable/c/645996efc2ae391246d595832aaa6f9d3cc338c7 |
| https://git.kernel.org/stable/c/fc658c083904427abbf8f18280d517ee2668677c |
| https://git.kernel.org/stable/c/fae05b2314b147a78fbed1dc4c645d9a66313758 |
| https://git.kernel.org/stable/c/3ec459c8810e658401be428d3168eacfc380bdd0 |
| https://git.kernel.org/stable/c/8ba7b7c1dad1f6503c541778f31b33f7f62eb966 |
| https://git.kernel.org/stable/c/c5402fb5f71f1a725f1e55d9c6799c0c7bec308f |
| https://git.kernel.org/stable/c/2505a981114dcb715f8977b8433f7540854851d8 |
