| From bippy-1.1.0 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-2022-49771: dm ioctl: fix misbehavior if list_versions races with module loading |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| dm ioctl: fix misbehavior if list_versions races with module loading |
| |
| __list_versions will first estimate the required space using the |
| "dm_target_iterate(list_version_get_needed, &needed)" call and then will |
| fill the space using the "dm_target_iterate(list_version_get_info, |
| &iter_info)" call. Each of these calls locks the targets using the |
| "down_read(&_lock)" and "up_read(&_lock)" calls, however between the first |
| and second "dm_target_iterate" there is no lock held and the target |
| modules can be loaded at this point, so the second "dm_target_iterate" |
| call may need more space than what was the first "dm_target_iterate" |
| returned. |
| |
| The code tries to handle this overflow (see the beginning of |
| list_version_get_info), however this handling is incorrect. |
| |
| The code sets "param->data_size = param->data_start + needed" and |
| "iter_info.end = (char *)vers+len" - "needed" is the size returned by the |
| first dm_target_iterate call; "len" is the size of the buffer allocated by |
| userspace. |
| |
| "len" may be greater than "needed"; in this case, the code will write up |
| to "len" bytes into the buffer, however param->data_size is set to |
| "needed", so it may write data past the param->data_size value. The ioctl |
| interface copies only up to param->data_size into userspace, thus part of |
| the result will be truncated. |
| |
| Fix this bug by setting "iter_info.end = (char *)vers + needed;" - this |
| guarantees that the second "dm_target_iterate" call will write only up to |
| the "needed" buffer and it will exit with "DM_BUFFER_FULL_FLAG" if it |
| overflows the "needed" space - in this case, userspace will allocate a |
| larger buffer and retry. |
| |
| Note that there is also a bug in list_version_get_needed - we need to add |
| "strlen(tt->name) + 1" to the needed size, not "strlen(tt->name)". |
| |
| The Linux kernel CVE team has assigned CVE-2022-49771 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Fixed in 4.9.334 with commit 0c8d4112df329bf3dfbf27693f918c3b08676538 |
| Fixed in 4.14.300 with commit 6a818db0d5aecf80d4ba9e10ac153f60adc629ca |
| Fixed in 4.19.267 with commit 3a1c35d72dc0b34d1e746ed705790c0f630aa427 |
| Fixed in 5.4.225 with commit b545c0e1e4094d4de2bdfe9a3823f9154b0c0005 |
| Fixed in 5.10.156 with commit f59f5a269ca5e43c567aca7f1f52500a0186e9b7 |
| Fixed in 5.15.80 with commit 6ffce7a92ef5c68f7e5d6f4d722c2f96280c064b |
| Fixed in 6.0.10 with commit 5398b8e275bf81a2517b327d216c0f37ac9ac5ae |
| Fixed in 6.1 with commit 4fe1ec995483737f3d2a14c3fe1d8fe634972979 |
| |
| 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-2022-49771 |
| 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/md/dm-ioctl.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/0c8d4112df329bf3dfbf27693f918c3b08676538 |
| https://git.kernel.org/stable/c/6a818db0d5aecf80d4ba9e10ac153f60adc629ca |
| https://git.kernel.org/stable/c/3a1c35d72dc0b34d1e746ed705790c0f630aa427 |
| https://git.kernel.org/stable/c/b545c0e1e4094d4de2bdfe9a3823f9154b0c0005 |
| https://git.kernel.org/stable/c/f59f5a269ca5e43c567aca7f1f52500a0186e9b7 |
| https://git.kernel.org/stable/c/6ffce7a92ef5c68f7e5d6f4d722c2f96280c064b |
| https://git.kernel.org/stable/c/5398b8e275bf81a2517b327d216c0f37ac9ac5ae |
| https://git.kernel.org/stable/c/4fe1ec995483737f3d2a14c3fe1d8fe634972979 |
