| 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-2022-49171: ext4: don't BUG if someone dirty pages without asking ext4 first |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| ext4: don't BUG if someone dirty pages without asking ext4 first |
| |
| [un]pin_user_pages_remote is dirtying pages without properly warning |
| the file system in advance. A related race was noted by Jan Kara in |
| 2018[1]; however, more recently instead of it being a very hard-to-hit |
| race, it could be reliably triggered by process_vm_writev(2) which was |
| discovered by Syzbot[2]. |
| |
| This is technically a bug in mm/gup.c, but arguably ext4 is fragile in |
| that if some other kernel subsystem dirty pages without properly |
| notifying the file system using page_mkwrite(), ext4 will BUG, while |
| other file systems will not BUG (although data will still be lost). |
| |
| So instead of crashing with a BUG, issue a warning (since there may be |
| potential data loss) and just mark the page as clean to avoid |
| unprivileged denial of service attacks until the problem can be |
| properly fixed. More discussion and background can be found in the |
| thread starting at [2]. |
| |
| [1] https://lore.kernel.org/linux-mm/20180103100430.GE4911@quack2.suse.cz |
| [2] https://lore.kernel.org/r/Yg0m6IjcNmfaSokM@google.com |
| |
| The Linux kernel CVE team has assigned CVE-2022-49171 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Fixed in 4.9.311 with commit 5db60e76edf5680ff1f3a7221036fc44b308f146 |
| Fixed in 4.14.276 with commit d666dfaa571465a19f014534a214c255ea33f301 |
| Fixed in 4.19.238 with commit 0d3a6926f7e8be3c897fa46216ce13b119a9f56a |
| Fixed in 5.4.189 with commit 5a016c053f426a73752c3b41b60b497b58694d48 |
| Fixed in 5.10.110 with commit 330d0e44fc5a47c27df958ecdd4693a3cb1d8b81 |
| Fixed in 5.15.33 with commit a0856764dc1276ad2dc7891288c2e9246bf11a37 |
| Fixed in 5.16.19 with commit 343117559ef41e992e326f7a92da1a8f254dfa8c |
| Fixed in 5.17.2 with commit 677c9d30e8487bee6c8e3b034070319d98f6e203 |
| Fixed in 5.18 with commit cc5095747edfb054ca2068d01af20be3fcc3634f |
| |
| 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-2022-49171 |
| 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/ext4/inode.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/5db60e76edf5680ff1f3a7221036fc44b308f146 |
| https://git.kernel.org/stable/c/d666dfaa571465a19f014534a214c255ea33f301 |
| https://git.kernel.org/stable/c/0d3a6926f7e8be3c897fa46216ce13b119a9f56a |
| https://git.kernel.org/stable/c/5a016c053f426a73752c3b41b60b497b58694d48 |
| https://git.kernel.org/stable/c/330d0e44fc5a47c27df958ecdd4693a3cb1d8b81 |
| https://git.kernel.org/stable/c/a0856764dc1276ad2dc7891288c2e9246bf11a37 |
| https://git.kernel.org/stable/c/343117559ef41e992e326f7a92da1a8f254dfa8c |
| https://git.kernel.org/stable/c/677c9d30e8487bee6c8e3b034070319d98f6e203 |
| https://git.kernel.org/stable/c/cc5095747edfb054ca2068d01af20be3fcc3634f |
