| 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-2024-57982: xfrm: state: fix out-of-bounds read during lookup |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| xfrm: state: fix out-of-bounds read during lookup |
| |
| lookup and resize can run in parallel. |
| |
| The xfrm_state_hash_generation seqlock ensures a retry, but the hash |
| functions can observe a hmask value that is too large for the new hlist |
| array. |
| |
| rehash does: |
| rcu_assign_pointer(net->xfrm.state_bydst, ndst) [..] |
| net->xfrm.state_hmask = nhashmask; |
| |
| While state lookup does: |
| h = xfrm_dst_hash(net, daddr, saddr, tmpl->reqid, encap_family); |
| hlist_for_each_entry_rcu(x, net->xfrm.state_bydst + h, bydst) { |
| |
| This is only safe in case the update to state_bydst is larger than |
| net->xfrm.xfrm_state_hmask (or if the lookup function gets |
| serialized via state spinlock again). |
| |
| Fix this by prefetching state_hmask and the associated pointers. |
| The xfrm_state_hash_generation seqlock retry will ensure that the pointer |
| and the hmask will be consistent. |
| |
| The existing helpers, like xfrm_dst_hash(), are now unsafe for RCU side, |
| add lockdep assertions to document that they are only safe for insert |
| side. |
| |
| xfrm_state_lookup_byaddr() uses the spinlock rather than RCU. |
| AFAICS this is an oversight from back when state lookup was converted to |
| RCU, this lock should be replaced with RCU in a future patch. |
| |
| The Linux kernel CVE team has assigned CVE-2024-57982 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 4.9 with commit c2f672fc94642bae96821a393f342edcfa9794a6 and fixed in 6.12.13 with commit a16871c7832ea6435abb6e0b58289ae7dcb7e4fc |
| Issue introduced in 4.9 with commit c2f672fc94642bae96821a393f342edcfa9794a6 and fixed in 6.13.2 with commit dd4c2a174994238d55ab54da2545543d36f4e0d0 |
| Issue introduced in 4.9 with commit c2f672fc94642bae96821a393f342edcfa9794a6 and fixed in 6.14 with commit e952837f3ddb0ff726d5b582aa1aad9aa38d024d |
| |
| 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-2024-57982 |
| 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: |
| net/xfrm/xfrm_state.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/a16871c7832ea6435abb6e0b58289ae7dcb7e4fc |
| https://git.kernel.org/stable/c/dd4c2a174994238d55ab54da2545543d36f4e0d0 |
| https://git.kernel.org/stable/c/e952837f3ddb0ff726d5b582aa1aad9aa38d024d |
