| From bippy-1.2.0 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-2025-37834: mm/vmscan: don't try to reclaim hwpoison folio |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| mm/vmscan: don't try to reclaim hwpoison folio |
| |
| Syzkaller reports a bug as follows: |
| |
| Injecting memory failure for pfn 0x18b00e at process virtual address 0x20ffd000 |
| Memory failure: 0x18b00e: dirty swapcache page still referenced by 2 users |
| Memory failure: 0x18b00e: recovery action for dirty swapcache page: Failed |
| page: refcount:2 mapcount:0 mapping:0000000000000000 index:0x20ffd pfn:0x18b00e |
| memcg:ffff0000dd6d9000 |
| anon flags: 0x5ffffe00482011(locked|dirty|arch_1|swapbacked|hwpoison|node=0|zone=2|lastcpupid=0xfffff) |
| raw: 005ffffe00482011 dead000000000100 dead000000000122 ffff0000e232a7c9 |
| raw: 0000000000020ffd 0000000000000000 00000002ffffffff ffff0000dd6d9000 |
| page dumped because: VM_BUG_ON_FOLIO(!folio_test_uptodate(folio)) |
| ------------[ cut here ]------------ |
| kernel BUG at mm/swap_state.c:184! |
| Internal error: Oops - BUG: 00000000f2000800 [#1] SMP |
| Modules linked in: |
| CPU: 0 PID: 60 Comm: kswapd0 Not tainted 6.6.0-gcb097e7de84e #3 |
| Hardware name: linux,dummy-virt (DT) |
| pstate: 80400005 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) |
| pc : add_to_swap+0xbc/0x158 |
| lr : add_to_swap+0xbc/0x158 |
| sp : ffff800087f37340 |
| x29: ffff800087f37340 x28: fffffc00052c0380 x27: ffff800087f37780 |
| x26: ffff800087f37490 x25: ffff800087f37c78 x24: ffff800087f377a0 |
| x23: ffff800087f37c50 x22: 0000000000000000 x21: fffffc00052c03b4 |
| x20: 0000000000000000 x19: fffffc00052c0380 x18: 0000000000000000 |
| x17: 296f696c6f662865 x16: 7461646f7470755f x15: 747365745f6f696c |
| x14: 6f6621284f494c4f x13: 0000000000000001 x12: ffff600036d8b97b |
| x11: 1fffe00036d8b97a x10: ffff600036d8b97a x9 : dfff800000000000 |
| x8 : 00009fffc9274686 x7 : ffff0001b6c5cbd3 x6 : 0000000000000001 |
| x5 : ffff0000c25896c0 x4 : 0000000000000000 x3 : 0000000000000000 |
| x2 : 0000000000000000 x1 : ffff0000c25896c0 x0 : 0000000000000000 |
| Call trace: |
| add_to_swap+0xbc/0x158 |
| shrink_folio_list+0x12ac/0x2648 |
| shrink_inactive_list+0x318/0x948 |
| shrink_lruvec+0x450/0x720 |
| shrink_node_memcgs+0x280/0x4a8 |
| shrink_node+0x128/0x978 |
| balance_pgdat+0x4f0/0xb20 |
| kswapd+0x228/0x438 |
| kthread+0x214/0x230 |
| ret_from_fork+0x10/0x20 |
| |
| I can reproduce this issue with the following steps: |
| |
| 1) When a dirty swapcache page is isolated by reclaim process and the |
| page isn't locked, inject memory failure for the page. |
| me_swapcache_dirty() clears uptodate flag and tries to delete from lru, |
| but fails. Reclaim process will put the hwpoisoned page back to lru. |
| |
| 2) The process that maps the hwpoisoned page exits, the page is deleted |
| the page will never be freed and will be in the lru forever. |
| |
| 3) If we trigger a reclaim again and tries to reclaim the page, |
| add_to_swap() will trigger VM_BUG_ON_FOLIO due to the uptodate flag is |
| cleared. |
| |
| To fix it, skip the hwpoisoned page in shrink_folio_list(). Besides, the |
| hwpoison folio may not be unmapped by hwpoison_user_mappings() yet, unmap |
| it in shrink_folio_list(), otherwise the folio will fail to be unmaped by |
| hwpoison_user_mappings() since the folio isn't in lru list. |
| |
| The Linux kernel CVE team has assigned CVE-2025-37834 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Fixed in 6.12.26 with commit 1c9798bf8145a92abf45aa9d38a6406d9eb8bdf0 |
| Fixed in 6.14.5 with commit 912e9f0300c3564b72a8808db406e313193a37ad |
| Fixed in 6.15 with commit 1b0449544c6482179ac84530b61fc192a6527bfd |
| |
| 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-2025-37834 |
| 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/vmscan.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/1c9798bf8145a92abf45aa9d38a6406d9eb8bdf0 |
| https://git.kernel.org/stable/c/912e9f0300c3564b72a8808db406e313193a37ad |
| https://git.kernel.org/stable/c/1b0449544c6482179ac84530b61fc192a6527bfd |
