+ mm-mmap-use-advanced-maple-tree-api-for-mmap_region-fix.patch added to mm-unstable branch

[Andrew Morton <akpm@linux-foundation.org>]

The patch titled
     Date: Wed, 13 Apr 2022 23:07:16 -0700
has been added to the -mm mm-unstable branch.  Its filename is
     mm-mmap-use-advanced-maple-tree-api-for-mmap_region-fix.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-mmap-use-advanced-maple-tree-api-for-mmap_region-fix.patch

This patch will later appear in the mm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: "Liam R. Howlett" <Liam.Howlett@Oracle.com>
Date: Wed, 13 Apr 2022 23:07:16 -0700
Subject: mm/mmap: fix advanced maple tree API for mmap_region()

Overwriting next pointer in mmap_region() breaks the error path in a
future patch.

Link: https://lkml.kernel.org/r/20220519020341.rr3s6b4dr7o36cqb@revolver
Signed-off-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Reported-by: <syzbot+ee1fdd8dcc770a3a169a@syzkaller.appspotmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/mmap.c |   12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

--- a/mm/mmap.c~mm-mmap-use-advanced-maple-tree-api-for-mmap_region-fix
+++ a/mm/mmap.c
@@ -1765,7 +1765,7 @@ unsigned long mmap_region(struct file *f
 {
 	struct mm_struct *mm = current->mm;
 	struct vm_area_struct *vma = NULL;
-	struct vm_area_struct *prev, *next;
+	struct vm_area_struct *next, *prev, *merge;
 	pgoff_t pglen = len >> PAGE_SHIFT;
 	unsigned long charged = 0;
 	unsigned long end = addr + len;
@@ -1883,19 +1883,17 @@ cannot_expand:
 		 * as we may succeed this time.
 		 */
 		if (unlikely(vm_flags != vma->vm_flags && prev)) {
-			next = vma_merge(mm, prev, vma->vm_start, vma->vm_end, vma->vm_flags,
+			merge = vma_merge(mm, prev, vma->vm_start, vma->vm_end, vma->vm_flags,
 				NULL, vma->vm_file, vma->vm_pgoff, NULL, NULL_VM_UFFD_CTX, NULL);
-			if (next) {
+			if (merge) {
 				/* ->mmap() can change vma->vm_file and fput the original file. So
 				 * fput the vma->vm_file here or we would add an extra fput for file
 				 * and cause general protection fault ultimately.
 				 */
 				fput(vma->vm_file);
 				vm_area_free(vma);
-				vma = prev;
-				/* Update vm_flags and possible addr to pick up the change. We don't
-				 * warn here if addr changed as the vma is not linked by vma_link().
-				 */
+				vma = merge;
+				/* Update vm_flags to pick up the change. */
 				addr = vma->vm_start;
 				vm_flags = vma->vm_flags;
 				goto unmap_writable;
_

Patches currently in -mm which might be from Liam.Howlett@Oracle.com are

mips-rename-mt_init-to-mips_mt_init.patch
maple-tree-add-new-data-structure.patch
radix-tree-test-suite-add-pr_err-define.patch
radix-tree-test-suite-add-kmem_cache_set_non_kernel.patch
radix-tree-test-suite-add-allocation-counts-and-size-to-kmem_cache.patch
radix-tree-test-suite-add-support-for-slab-bulk-apis.patch
radix-tree-test-suite-add-lockdep_is_held-to-header.patch
lib-test_maple_tree-add-testing-for-maple-tree.patch
mm-start-tracking-vmas-with-maple-tree.patch
mm-mmap-use-the-maple-tree-in-find_vma-instead-of-the-rbtree.patch
mm-mmap-use-the-maple-tree-for-find_vma_prev-instead-of-the-rbtree.patch
mm-mmap-use-maple-tree-for-unmapped_area_topdown.patch
kernel-fork-use-maple-tree-for-dup_mmap-during-forking.patch
damon-convert-__damon_va_three_regions-to-use-the-vma-iterator.patch
mm-remove-rb-tree.patch
mmap-change-zeroing-of-maple-tree-in-__vma_adjust.patch
xen-use-vma_lookup-in-privcmd_ioctl_mmap.patch
mm-optimize-find_exact_vma-to-use-vma_lookup.patch
mm-khugepaged-optimize-collapse_pte_mapped_thp-by-using-vma_lookup.patch
mm-mmap-change-do_brk_flags-to-expand-existing-vma-and-add-do_brk_munmap.patch
mm-use-maple-tree-operations-for-find_vma_intersection.patch
mm-mmap-use-advanced-maple-tree-api-for-mmap_region.patch
mm-mmap-use-advanced-maple-tree-api-for-mmap_region-fix.patch
mm-remove-vmacache.patch
mm-convert-vma_lookup-to-use-mtree_load.patch
mm-mmap-move-mmap_region-below-do_munmap.patch
mm-mmap-reorganize-munmap-to-use-maple-states.patch
mm-mmap-change-do_brk_munmap-to-use-do_mas_align_munmap.patch
arm64-change-elfcore-for_each_mte_vma-to-use-vma-iterator.patch
fs-proc-base-use-maple-tree-iterators-in-place-of-linked-list.patch
userfaultfd-use-maple-tree-iterator-to-iterate-vmas.patch
ipc-shm-use-vma-iterator-instead-of-linked-list.patch
bpf-remove-vma-linked-list.patch
mm-gup-use-maple-tree-navigation-instead-of-linked-list.patch
mm-madvise-use-vma_find-instead-of-vma-linked-list.patch
mm-memcontrol-stop-using-mm-highest_vm_end.patch
mm-mempolicy-use-vma-iterator-maple-state-instead-of-vma-linked-list.patch
mm-mprotect-use-maple-tree-navigation-instead-of-vma-linked-list.patch
mm-mremap-use-vma_find_intersection-instead-of-vma-linked-list.patch
mm-msync-use-vma_find-instead-of-vma-linked-list.patch
mm-oom_kill-use-maple-tree-iterators-instead-of-vma-linked-list.patch
mm-swapfile-use-vma-iterator-instead-of-vma-linked-list.patch
riscv-use-vma-iterator-for-vdso.patch
mm-remove-the-vma-linked-list.patch
mm-mmap-drop-range_has_overlap-function.patch
mm-mmapc-pass-in-mapping-to-__vma_link_file.patch