| 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-2022-49810: netfs: Fix missing xas_retry() calls in xarray iteration |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| netfs: Fix missing xas_retry() calls in xarray iteration |
| |
| netfslib has a number of places in which it performs iteration of an xarray |
| whilst being under the RCU read lock. It *should* call xas_retry() as the |
| first thing inside of the loop and do "continue" if it returns true in case |
| the xarray walker passed out a special value indicating that the walk needs |
| to be redone from the root[*]. |
| |
| Fix this by adding the missing retry checks. |
| |
| [*] I wonder if this should be done inside xas_find(), xas_next_node() and |
| suchlike, but I'm told that's not an simple change to effect. |
| |
| This can cause an oops like that below. Note the faulting address - this |
| is an internal value (|0x2) returned from xarray. |
| |
| BUG: kernel NULL pointer dereference, address: 0000000000000402 |
| ... |
| RIP: 0010:netfs_rreq_unlock+0xef/0x380 [netfs] |
| ... |
| Call Trace: |
| netfs_rreq_assess+0xa6/0x240 [netfs] |
| netfs_readpage+0x173/0x3b0 [netfs] |
| ? init_wait_var_entry+0x50/0x50 |
| filemap_read_page+0x33/0xf0 |
| filemap_get_pages+0x2f2/0x3f0 |
| filemap_read+0xaa/0x320 |
| ? do_filp_open+0xb2/0x150 |
| ? rmqueue+0x3be/0xe10 |
| ceph_read_iter+0x1fe/0x680 [ceph] |
| ? new_sync_read+0x115/0x1a0 |
| new_sync_read+0x115/0x1a0 |
| vfs_read+0xf3/0x180 |
| ksys_read+0x5f/0xe0 |
| do_syscall_64+0x38/0x90 |
| entry_SYSCALL_64_after_hwframe+0x44/0xae |
| |
| Changes: |
| ======== |
| ver #2) |
| - Changed an unsigned int to a size_t to reduce the likelihood of an |
| overflow as per Willy's suggestion. |
| - Added an additional patch to fix the maths. |
| |
| The Linux kernel CVE team has assigned CVE-2022-49810 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 5.13 with commit 3d3c95046742e4eebaa4b891b0b01cbbed94ebbd and fixed in 6.0.10 with commit b2cc07a76f1eb12de3b22caf5fdbf856a7bef16d |
| Issue introduced in 5.13 with commit 3d3c95046742e4eebaa4b891b0b01cbbed94ebbd and fixed in 6.1 with commit 7e043a80b5dae5c2d2cf84031501de7827fd6c00 |
| |
| 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-2022-49810 |
| 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/netfs/buffered_read.c |
| fs/netfs/io.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/b2cc07a76f1eb12de3b22caf5fdbf856a7bef16d |
| https://git.kernel.org/stable/c/7e043a80b5dae5c2d2cf84031501de7827fd6c00 |
