Merge tag 'mm-hotfixes-stable-2022-12-10-1' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull misc fixes from Andrew Morton:
 "Nine hotfixes.

  Six for MM, three for other areas. Four of these patches address
  post-6.0 issues"

* tag 'mm-hotfixes-stable-2022-12-10-1' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm:
  memcg: fix possible use-after-free in memcg_write_event_control()
  MAINTAINERS: update Muchun Song's email
  mm/gup: fix gup_pud_range() for dax
  mmap: fix do_brk_flags() modifying obviously incorrect VMAs
  mm/swap: fix SWP_PFN_BITS with CONFIG_PHYS_ADDR_T_64BIT on 32bit
  tmpfs: fix data loss from failed fallocate
  kselftests: cgroup: update kmem test precision tolerance
  mm: do not BUG_ON missing brk mapping, because userspace can unmap it
  mailmap: update Matti Vaittinen's email address

1 files changed, 4 insertions, 10 deletions

diff --git a/mm/mmap.c b/mm/mmap.c
index a5eb2f175da0a..54abd46e60078 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -226,8 +226,7 @@ SYSCALL_DEFINE1(brk, unsigned long, brk)
 		/* Search one past newbrk */
 		mas_set(&mas, newbrk);
 		brkvma = mas_find(&mas, oldbrk);
-		BUG_ON(brkvma == NULL);
-		if (brkvma->vm_start >= oldbrk)
+		if (!brkvma || brkvma->vm_start >= oldbrk)
 			goto out; /* mapping intersects with an existing non-brk vma. */
 		/*
 		 * mm->brk must be protected by write mmap_lock.
@@ -2946,9 +2945,9 @@ static int do_brk_flags(struct ma_state *mas, struct vm_area_struct *vma,
 	 * Expand the existing vma if possible; Note that singular lists do not
 	 * occur after forking, so the expand will only happen on new VMAs.
 	 */
-	if (vma &&
-	    (!vma->anon_vma || list_is_singular(&vma->anon_vma_chain)) &&
-	    ((vma->vm_flags & ~VM_SOFTDIRTY) == flags)) {
+	if (vma && vma->vm_end == addr && !vma_policy(vma) &&
+	    can_vma_merge_after(vma, flags, NULL, NULL,
+				addr >> PAGE_SHIFT, NULL_VM_UFFD_CTX, NULL)) {
 		mas_set_range(mas, vma->vm_start, addr + len - 1);
 		if (mas_preallocate(mas, vma, GFP_KERNEL))
 			return -ENOMEM;
@@ -3035,11 +3034,6 @@ int vm_brk_flags(unsigned long addr, unsigned long request, unsigned long flags)
 		goto munmap_failed;
 
 	vma = mas_prev(&mas, 0);
-	if (!vma || vma->vm_end != addr || vma_policy(vma) ||
-	    !can_vma_merge_after(vma, flags, NULL, NULL,
-				 addr >> PAGE_SHIFT, NULL_VM_UFFD_CTX, NULL))
-		vma = NULL;
-
 	ret = do_brk_flags(&mas, vma, addr, len, flags);
 	populate = ((mm->def_flags & VM_LOCKED) != 0);
 	mmap_write_unlock(mm);