On Mon, Oct 28, 2024 at 09:12:05PM -0700, Andrew Morton wrote:

The patch titled Subject: mm/mlock: set the correct prev on failure has been added to the -mm mm-unstable branch. Its filename is mm-mlock-set-the-correct-prev-on-failure.patch

Hi Andrew,

This patch needs to be applied as a hotfix as it fixes a bug in released kernels.

Thanks!

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-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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---

From: Wei Yang richard.weiyang@gmail.com Subject: mm/mlock: set the correct prev on failure Date: Sun, 27 Oct 2024 12:33:21 +0000

After commit 94d7d9233951 ("mm: abstract the vma_merge()/split_vma() pattern for mprotect() et al."), if vma_modify_flags() return error, the vma is set to an error code. This will lead to an invalid prev be returned.

Generally this shouldn't matter as the caller should treat an error as indicating state is now invalidated, however unfortunately apply_mlockall_flags() does not check for errors and assumes that mlock_fixup() correctly maintains prev even if an error were to occur.

This patch fixes that assumption.

[lorenzo.stoakes@oracle.com: provide a better fix and rephrase the log] Link: https://lkml.kernel.org/r/20241027123321.19511-1-richard.weiyang@gmail.com Fixes: 94d7d9233951 ("mm: abstract the vma_merge()/split_vma() pattern for mprotect() et al.") Signed-off-by: Wei Yang richard.weiyang@gmail.com Reviewed-by: Lorenzo Stoakes lorenzo.stoakes@oracle.com Reviewed-by: Liam R. Howlett Liam.Howlett@Oracle.com Cc: Vlastimil Babka vbabka@suse.cz Cc: Jann Horn jannh@google.com Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org

---

mm/mlock.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-)

--- a/mm/mlock.c~mm-mlock-set-the-correct-prev-on-failure +++ a/mm/mlock.c @@ -725,14 +725,17 @@ static int apply_mlockall_flags(int flag }

for_each_vma(vmi, vma) {

• int error;
  

  vm_flags_t newflags;

  newflags = vma->vm_flags & ~VM_LOCKED_MASK; newflags |= to_add;

• /* Ignore errors */
  

• mlock_fixup(&vmi, vma, &prev, vma->vm_start, vma->vm_end,
  

• 	    newflags);
  

• error = mlock_fixup(&vmi, vma, &prev, vma->vm_start, vma->vm_end,
  

• 		    newflags);
  

• /* Ignore errors, but prev needs fixing up. */
  

• if (error)
  

• 	prev = vma;
  

  cond_resched(); }

out: _

Patches currently in -mm which might be from richard.weiyang@gmail.com are

maple_tree-i-is-always-less-than-or-equal-to-mas_end.patch maple_tree-goto-complete-directly-on-a-pivot-of-0.patch maple_tree-remove-maple_big_nodeparent.patch maple_tree-memset-maple_big_node-as-a-whole.patch maple_tree-root-node-could-be-handled-by-p_slot-too.patch maple_tree-clear-request_count-for-new-allocated-one.patch maple_tree-total-is-not-changed-for-nomem_one-case.patch maple_tree-simplify-mas_push_node.patch maple_tree-calculate-new_end-when-needed.patch maple_tree-remove-sanity-check-from-mas_wr_slot_store.patch mm-vma-the-pgoff-is-correct-if-can_merge_right.patch mm-mlock-set-the-correct-prev-on-failure.patch