mm-mempolicy-fix-migrate_to_node-assuming-there-is-at-least-one-vma-in-a-mm.patch removed from -mm tree

The quilt patch titled
Subject: mm/mempolicy: fix migrate_to_node() assuming there is at least one VMA in a MM
has been removed from the -mm tree. Its filename was
mm-mempolicy-fix-migrate_to_node-assuming-there-is-at-least-one-vma-in-a-mm.patch

This patch was dropped because it was merged into the mm-hotfixes-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

------------------------------------------------------
From: David Hildenbrand <[email protected]>
Subject: mm/mempolicy: fix migrate_to_node() assuming there is at least one VMA in a MM
Date: Wed, 20 Nov 2024 21:11:51 +0100

We currently assume that there is at least one VMA in a MM, which isn't true.

So we might end up having find_vma() return NULL, to then de-reference NULL. So properly handle find_vma() returning NULL.

This fixes the report:

Oops: general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
CPU: 1 UID: 0 PID: 6021 Comm: syz-executor284 Not tainted 6.12.0-rc7-syzkaller-00187-gf868cd251776 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/30/2024
RIP: 0010:migrate_to_node mm/mempolicy.c:1090 [inline]
RIP: 0010:do_migrate_pages+0x403/0x6f0 mm/mempolicy.c:1194
Code: ...
RSP: 0018:ffffc9000375fd08 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffffc9000375fd78 RCX: 0000000000000000
RDX: ffff88807e171300 RSI: dffffc0000000000 RDI: ffff88803390c044
RBP: ffff88807e171428 R08: 0000000000000014 R09: fffffbfff2039ef1
R10: ffffffff901cf78f R11: 0000000000000000 R12: 0000000000000003
R13: ffffc9000375fe90 R14: ffffc9000375fe98 R15: ffffc9000375fdf8
FS:  00005555919e1380(0000) GS:ffff8880b8700000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005555919e1ca8 CR3: 000000007f12a000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 kernel_migrate_pages+0x5b2/0x750 mm/mempolicy.c:1709
 __do_sys_migrate_pages mm/mempolicy.c:1727 [inline]
 __se_sys_migrate_pages mm/mempolicy.c:1723 [inline]
 __x64_sys_migrate_pages+0x96/0x100 mm/mempolicy.c:1723
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

---

 mm/mempolicy.c |    4 ++++
 1 file changed, 4 insertions(+)

@@ -1080,6 +1080,10 @@ static long migrate_to_node(struct mm_st
 
 	mmap_read_lock(mm);
 	vma = find_vma(mm, 0);
+	if (unlikely(!vma)) {
+		mmap_read_unlock(mm);
+		return 0;
+	}
 
 	/*
 	 * This does not migrate the range, but isolates all pages that

_

Patches currently in -mm which might be from [email protected] are

docs-tmpfs-update-the-large-folios-policy-for-tmpfs-and-shmem.patch mm-memory_hotplug-move-debug_pagealloc_map_pages-into-online_pages_range.patch mm-page_isolation-dont-pass-gfp-flags-to-isolate_single_pageblock.patch mm-page_isolation-dont-pass-gfp-flags-to-start_isolate_page_range.patch mm-page_alloc-make-__alloc_contig_migrate_range-static.patch mm-page_alloc-sort-out-the-alloc_contig_range-gfp-flags-mess.patch mm-page_alloc-forward-the-gfp-flags-from-alloc_contig_range-to-post_alloc_hook.patch powernv-memtrace-use-__gfp_zero-with-alloc_contig_pages.patch mm-hugetlb-dont-map-folios-writable-without-vm_write-when-copying-during-fork.patch fs-proc-vmcore-convert-vmcore_cb_lock-into-vmcore_mutex.patch fs-proc-vmcore-replace-vmcoredd_mutex-by-vmcore_mutex.patch fs-proc-vmcore-disallow-vmcore-modifications-while-the-vmcore-is-open.patch fs-proc-vmcore-prefix-all-pr_-with-vmcore.patch fs-proc-vmcore-move-vmcore-definitions-out-of-kcoreh.patch fs-proc-vmcore-factor-out-allocating-a-vmcore-range-and-adding-it-to-a-list.patch fs-proc-vmcore-factor-out-freeing-a-list-of-vmcore-ranges.patch fs-proc-vmcore-introduce-proc_vmcore_device_ram-to-detect-device-ram-ranges-in-2nd-kernel.patch virtio-mem-mark-device-ready-before-registering-callbacks-in-kdump-mode.patch virtio-mem-remember-usable-region-size.patch virtio-mem-support-config_proc_vmcore_device_ram.patch s390-kdump-virtio-mem-kdump-support-config_proc_vmcore_device_ram.patch