diff options
| author | Lorenzo Stoakes <lorenzo.stoakes@oracle.com> | 2025-08-03 12:11:22 +0100 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2025-08-19 16:35:55 -0700 |
| commit | d5f416c7c36456676c2cf5ab98776db2e7601f27 (patch) | |
| tree | 725dc4b0f025b1909ecce6b297a1056a54fd6d90 /mm/mremap.c | |
| parent | 7c91e0b91aaa3fa1f897efb06565af0ceb75195c (diff) | |
mm/mremap: catch invalid multi VMA moves earlier
Previously, any attempt to solely move a VMA would require that the
span specified reside within the span of that single VMA, with no gaps
before or afterwards.
After commit d23cb648e365 ("mm/mremap: permit mremap() move of multiple
VMAs"), the multi VMA move permitted a gap to exist only after VMAs.
This was done to provide maximum flexibility.
However, We have consequently permitted this behaviour for the move of
a single VMA including those not eligible for multi VMA move.
The change introduced here means that we no longer permit non-eligible
VMAs from being moved in this way.
This is consistent, as it means all eligible VMA moves are treated the
same, and all non-eligible moves are treated as they were before.
This change does not break previous behaviour, which equally would have
disallowed such a move (only in all cases).
[lorenzo.stoakes@oracle.com: do not incorrectly reference invalid VMA in VM_WARN_ON_ONCE()]
Link: https://lkml.kernel.org/r/b6dbda20-667e-4053-abae-8ed4fa84bb6c@lucifer.local
Link: https://lkml.kernel.org/r/2b5aad5681573be85b5b8fac61399af6fb6b68b6.1754218667.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jann Horn <jannh@google.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm/mremap.c')
| -rw-r--r-- | mm/mremap.c | 21 |
1 files changed, 13 insertions, 8 deletions
diff --git a/mm/mremap.c b/mm/mremap.c index eb37d1668770..33b642076205 100644 --- a/mm/mremap.c +++ b/mm/mremap.c @@ -1820,10 +1820,11 @@ static unsigned long remap_move(struct vma_remap_struct *vrm) unsigned long start = vrm->addr; unsigned long end = vrm->addr + vrm->old_len; unsigned long new_addr = vrm->new_addr; - bool allowed = true, seen_vma = false; unsigned long target_addr = new_addr; unsigned long res = -EFAULT; unsigned long last_end; + bool seen_vma = false; + VMA_ITERATOR(vmi, current->mm, start); /* @@ -1836,9 +1837,7 @@ static unsigned long remap_move(struct vma_remap_struct *vrm) unsigned long addr = max(vma->vm_start, start); unsigned long len = min(end, vma->vm_end) - addr; unsigned long offset, res_vma; - - if (!allowed) - return -EFAULT; + bool multi_allowed; /* No gap permitted at the start of the range. */ if (!seen_vma && start < vma->vm_start) @@ -1867,9 +1866,15 @@ static unsigned long remap_move(struct vma_remap_struct *vrm) vrm->new_addr = target_addr + offset; vrm->old_len = vrm->new_len = len; - allowed = vma_multi_allowed(vma); - if (seen_vma && !allowed) - return -EFAULT; + multi_allowed = vma_multi_allowed(vma); + if (!multi_allowed) { + /* This is not the first VMA, abort immediately. */ + if (seen_vma) + return -EFAULT; + /* This is the first, but there are more, abort. */ + if (vma->vm_end < end) + return -EFAULT; + } res_vma = check_prep_vma(vrm); if (!res_vma) @@ -1878,7 +1883,7 @@ static unsigned long remap_move(struct vma_remap_struct *vrm) return res_vma; if (!seen_vma) { - VM_WARN_ON_ONCE(allowed && res_vma != new_addr); + VM_WARN_ON_ONCE(multi_allowed && res_vma != new_addr); res = res_vma; } |