The patch titled Subject: mmap: fix error paths with dup_anon_vma() has been added to the -mm mm-hotfixes-unstable branch. Its filename is mmap-fix-error-paths-with-dup_anon_vma.patch

This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches...

This patch will later appear in the mm-hotfixes-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 Subject: mmap: fix error paths with dup_anon_vma() Date: Wed, 27 Sep 2023 12:07:45 -0400

When the calling function fails after the dup_anon_vma(), the duplication of the anon_vma is not being undone. Add the necessary unlink_anon_vma() call to the error paths that are missing them.

This issue showed up during inspection of the error path in vma_merge() for an unrelated vma iterator issue.

Users may experience increased memory usage, which may be problematic as the failure would likely be caused by a low memory situation.

Link: https://lkml.kernel.org/r/20230927160746.1928098-3-Liam.Howlett@oracle.com Fixes: d4af56c5c7c6 ("mm: start tracking VMAs with maple tree") Cc: Jann Horn jannh@google.com Signed-off-by: Liam R. Howlett Liam.Howlett@oracle.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

mm/mmap.c | 20 ++++++++++++++------ 1 file changed, 14 insertions(+), 6 deletions(-)

--- a/mm/mmap.c~mmap-fix-error-paths-with-dup_anon_vma +++ a/mm/mmap.c @@ -587,7 +587,7 @@ again: * Returns: 0 on success. */ static inline int dup_anon_vma(struct vm_area_struct *dst, - struct vm_area_struct *src) + struct vm_area_struct *src, struct vm_area_struct **dup) { /* * Easily overlooked: when mprotect shifts the boundary, make sure the @@ -597,6 +597,7 @@ static inline int dup_anon_vma(struct vm if (src->anon_vma && !dst->anon_vma) { vma_assert_write_locked(dst); dst->anon_vma = src->anon_vma; + *dup = dst; return anon_vma_clone(dst, src); }

@@ -624,6 +625,7 @@ int vma_expand(struct vma_iterator *vmi, unsigned long start, unsigned long end, pgoff_t pgoff, struct vm_area_struct *next) { + struct vm_area_struct *anon_dup = NULL; bool remove_next = false; struct vma_prepare vp;

@@ -633,7 +635,7 @@ int vma_expand(struct vma_iterator *vmi,

remove_next = true; vma_start_write(next); - ret = dup_anon_vma(vma, next); + ret = dup_anon_vma(vma, next, &anon_dup); if (ret) return ret; } @@ -661,6 +663,8 @@ int vma_expand(struct vma_iterator *vmi, return 0;

nomem: + if (anon_dup) + unlink_anon_vmas(anon_dup); return -ENOMEM; }

@@ -860,6 +864,7 @@ struct vm_area_struct *vma_merge(struct { struct vm_area_struct *curr, *next, *res; struct vm_area_struct *vma, *adjust, *remove, *remove2; + struct vm_area_struct *anon_dup = NULL; struct vma_prepare vp; pgoff_t vma_pgoff; int err = 0; @@ -927,18 +932,18 @@ struct vm_area_struct *vma_merge(struct vma_start_write(next); remove = next; /* case 1 */ vma_end = next->vm_end; - err = dup_anon_vma(prev, next); + err = dup_anon_vma(prev, next, &anon_dup); if (curr) { /* case 6 */ vma_start_write(curr); remove = curr; remove2 = next; if (!next->anon_vma) - err = dup_anon_vma(prev, curr); + err = dup_anon_vma(prev, curr, &anon_dup); } } else if (merge_prev) { /* case 2 */ if (curr) { vma_start_write(curr); - err = dup_anon_vma(prev, curr); + err = dup_anon_vma(prev, curr, &anon_dup); if (end == curr->vm_end) { /* case 7 */ remove = curr; } else { /* case 5 */ @@ -954,7 +959,7 @@ struct vm_area_struct *vma_merge(struct vma_end = addr; adjust = next; adj_start = -(prev->vm_end - addr); - err = dup_anon_vma(next, prev); + err = dup_anon_vma(next, prev, &anon_dup); } else { /* * Note that cases 3 and 8 are the ONLY ones where prev @@ -1018,6 +1023,9 @@ struct vm_area_struct *vma_merge(struct return res;

prealloc_fail: + if (anon_dup) + unlink_anon_vmas(anon_dup); + anon_vma_fail: if (merge_prev) vma_next(vmi); _

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

maple_tree-add-mas_active-to-detect-in-tree-walks.patch maple_tree-add-mas_underflow-and-mas_overflow-states.patch mmap-fix-vma_iterator-in-error-path-of-vma_merge.patch mmap-fix-error-paths-with-dup_anon_vma.patch mmap-add-clarifying-comment-to-vma_merge-code.patch