From e0f81ab1e4f42ffece6440dc78f583eb352b9a71 Mon Sep 17 00:00:00 2001 From: Sebastian Ott Date: Fri, 29 Sep 2023 10:19:41 -0700 Subject: mm: fix vm_brk_flags() to not bail out while holding lock Calling vm_brk_flags() with flags set other than VM_EXEC will exit the function without releasing the mmap_write_lock. Just do the sanity check before the lock is acquired. This doesn't fix an actual issue since no caller sets a flag other than VM_EXEC. Link: https://lkml.kernel.org/r/20230929171937.work.697-kees@kernel.org Fixes: 2e7ce7d354f2 ("mm/mmap: change do_brk_flags() to expand existing VMA and add do_brk_munmap()") Signed-off-by: Sebastian Ott Signed-off-by: Kees Cook Reviewed-by: Liam R. Howlett Cc: Yu Zhao Signed-off-by: Andrew Morton --- mm/mmap.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'mm/mmap.c') diff --git a/mm/mmap.c b/mm/mmap.c index b56a7f0c9f85..7ed286662839 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -3143,13 +3143,13 @@ int vm_brk_flags(unsigned long addr, unsigned long request, unsigned long flags) if (!len) return 0; - if (mmap_write_lock_killable(mm)) - return -EINTR; - /* Until we need other flags, refuse anything except VM_EXEC. */ if ((flags & (~VM_EXEC)) != 0) return -EINVAL; + if (mmap_write_lock_killable(mm)) + return -EINTR; + ret = check_brk_limits(addr, len); if (ret) goto limits_failed; -- cgit From 1419430c8abb5a00590169068590dd54d86590ba Mon Sep 17 00:00:00 2001 From: "Liam R. Howlett" Date: Fri, 29 Sep 2023 14:30:39 -0400 Subject: mmap: fix vma_iterator in error path of vma_merge() During the error path, the vma iterator may not be correctly positioned or set to the correct range. Undo the vma_prev() call by resetting to the passed in address. Re-walking to the same range will fix the range to the area previously passed in. Users would notice increased cycles as vma_merge() would be called an extra time with vma == prev, and thus would fail to merge and return. Link: https://lore.kernel.org/linux-mm/CAG48ez12VN1JAOtTNMY+Y2YnsU45yL5giS-Qn=ejtiHpgJAbdQ@mail.gmail.com/ Link: https://lkml.kernel.org/r/20230929183041.2835469-2-Liam.Howlett@oracle.com Fixes: 18b098af2890 ("vma_merge: set vma iterator to correct position.") Signed-off-by: Liam R. Howlett Reported-by: Jann Horn Closes: https://lore.kernel.org/linux-mm/CAG48ez12VN1JAOtTNMY+Y2YnsU45yL5giS-Qn=ejtiHpgJAbdQ@mail.gmail.com/ Reviewed-by: Lorenzo Stoakes Acked-by: Vlastimil Babka Cc: Matthew Wilcox (Oracle) Cc: Suren Baghdasaryan Cc: Signed-off-by: Andrew Morton --- mm/mmap.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) (limited to 'mm/mmap.c') diff --git a/mm/mmap.c b/mm/mmap.c index 7ed286662839..a0917ed26057 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -975,7 +975,7 @@ struct vm_area_struct *vma_merge(struct vma_iterator *vmi, struct mm_struct *mm, /* Error in anon_vma clone. */ if (err) - return NULL; + goto anon_vma_fail; if (vma_start < vma->vm_start || vma_end > vma->vm_end) vma_expanded = true; @@ -988,7 +988,7 @@ struct vm_area_struct *vma_merge(struct vma_iterator *vmi, struct mm_struct *mm, } if (vma_iter_prealloc(vmi, vma)) - return NULL; + goto prealloc_fail; init_multi_vma_prep(&vp, vma, adjust, remove, remove2); VM_WARN_ON(vp.anon_vma && adjust && adjust->anon_vma && @@ -1016,6 +1016,12 @@ struct vm_area_struct *vma_merge(struct vma_iterator *vmi, struct mm_struct *mm, vma_complete(&vp, vmi, mm); khugepaged_enter_vma(res, vm_flags); return res; + +prealloc_fail: +anon_vma_fail: + vma_iter_set(vmi, addr); + vma_iter_load(vmi); + return NULL; } /* -- cgit From 824135c46b00df7fb369ec7f1f8607427bbebeb0 Mon Sep 17 00:00:00 2001 From: "Liam R. Howlett" Date: Fri, 29 Sep 2023 14:30:40 -0400 Subject: mmap: fix error paths with dup_anon_vma() 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/20230929183041.2835469-3-Liam.Howlett@oracle.com Fixes: d4af56c5c7c6 ("mm: start tracking VMAs with maple tree") Signed-off-by: Liam R. Howlett Reviewed-by: Lorenzo Stoakes Acked-by: Vlastimil Babka Cc: Jann Horn Cc: Matthew Wilcox (Oracle) Cc: Suren Baghdasaryan Cc: Signed-off-by: Andrew Morton --- mm/mmap.c | 30 ++++++++++++++++++++++-------- 1 file changed, 22 insertions(+), 8 deletions(-) (limited to 'mm/mmap.c') diff --git a/mm/mmap.c b/mm/mmap.c index a0917ed26057..9e018d8dd7d6 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -583,11 +583,12 @@ again: * dup_anon_vma() - Helper function to duplicate anon_vma * @dst: The destination VMA * @src: The source VMA + * @dup: Pointer to the destination VMA when successful. * * 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 @@ -595,9 +596,15 @@ static inline int dup_anon_vma(struct vm_area_struct *dst, * anon pages imported. */ if (src->anon_vma && !dst->anon_vma) { + int ret; + vma_assert_write_locked(dst); dst->anon_vma = src->anon_vma; - return anon_vma_clone(dst, src); + ret = anon_vma_clone(dst, src); + if (ret) + return ret; + + *dup = dst; } return 0; @@ -624,6 +631,7 @@ int vma_expand(struct vma_iterator *vmi, struct vm_area_struct *vma, 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 +641,7 @@ int vma_expand(struct vma_iterator *vmi, struct vm_area_struct *vma, 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 +669,8 @@ int vma_expand(struct vma_iterator *vmi, struct vm_area_struct *vma, return 0; nomem: + if (anon_dup) + unlink_anon_vmas(anon_dup); return -ENOMEM; } @@ -860,6 +870,7 @@ struct vm_area_struct *vma_merge(struct vma_iterator *vmi, struct mm_struct *mm, { 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 +938,18 @@ struct vm_area_struct *vma_merge(struct vma_iterator *vmi, struct mm_struct *mm, 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 +965,7 @@ struct vm_area_struct *vma_merge(struct vma_iterator *vmi, struct mm_struct *mm, 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 @@ -968,7 +979,7 @@ struct vm_area_struct *vma_merge(struct vma_iterator *vmi, struct mm_struct *mm, vma_pgoff = curr->vm_pgoff; vma_start_write(curr); remove = curr; - err = dup_anon_vma(next, curr); + err = dup_anon_vma(next, curr, &anon_dup); } } } @@ -1018,6 +1029,9 @@ struct vm_area_struct *vma_merge(struct vma_iterator *vmi, struct mm_struct *mm, return res; prealloc_fail: + if (anon_dup) + unlink_anon_vmas(anon_dup); + anon_vma_fail: vma_iter_set(vmi, addr); vma_iter_load(vmi); -- cgit