The patch titled
Subject: mmap: fix do_brk_flags() modifying obviously incorrect VMAs
has been added to the -mm mm-unstable branch. Its filename is
mmap-fix-do_brk_flags-modifying-obviously-incorrect-vmas.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mmap-fix-do_brk_flags-modifying-obviously-incorrect-vmas.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 Howlett <liam.howlett@xxxxxxxxxx>
Subject: mmap: fix do_brk_flags() modifying obviously incorrect VMAs
Date: Mon, 5 Dec 2022 19:23:17 +0000
Add more sanity checks to the VMA that do_brk_flags() will expand. Ensure
the VMA matches basic merge requirements within the function before
calling can_vma_merge_after().
Drop the duplicate checks from vm_brk_flags() since they will be enforced
later.
Link: https://lkml.kernel.org/r/20221205192304.1957418-1-Liam.Howlett@xxxxxxxxxx
Fixes: 2e7ce7d354f2 ("mm/mmap: change do_brk_flags() to expand existing VMA and add do_brk_munmap()")
Signed-off-by: Liam R. Howlett <Liam.Howlett@xxxxxxxxxx>
Suggested-by: Jann Horn <jannh@xxxxxxxxxx>
Cc: Jason A. Donenfeld <Jason@xxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: SeongJae Park <sj@xxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Yu Zhao <yuzhao@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/mmap.c | 11 +++--------
1 file changed, 3 insertions(+), 8 deletions(-)
--- a/mm/mmap.c~mmap-fix-do_brk_flags-modifying-obviously-incorrect-vmas
+++ a/mm/mmap.c
@@ -2945,9 +2945,9 @@ static int do_brk_flags(struct ma_state
* 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))
goto unacct_fail;
@@ -3034,11 +3034,6 @@ int vm_brk_flags(unsigned long addr, uns
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);
_
Patches currently in -mm which might be from liam.howlett@xxxxxxxxxx are
mmap-fix-do_brk_flags-modifying-obviously-incorrect-vmas.patch
maple_tree-fix-mas_find_rev-comment.patch
maple_tree-update-copyright-dates-for-test-code.patch
