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userfaultfd: fix PTE unmapping stack-allocated PTE copies 

Current implementation of move_pages_pte() copies source and destination
PTEs in order to detect concurrent changes to PTEs involved in the move. 
However these copies are also used to unmap the PTEs, which will fail if
CONFIG_HIGHPTE is enabled because the copies are allocated on the stack. 
Fix this by using the actual PTEs which were kmap()ed.

Link: https://lkml.kernel.org/r/20250226185510.2732648-3-surenb@google.com
Fixes: adef440691 ("userfaultfd: UFFDIO_MOVE uABI")
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Reported-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Barry Song <21cnbao@gmail.com>
Cc: Barry Song <v-songbaohua@oppo.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: Kalesh Singh <kaleshsingh@google.com>
Cc: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Lokesh Gidra <lokeshgidra@google.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Matthew Wilcow (Oracle) <willy@infradead.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Suren Baghdasaryan 2025-02-26 10:55:09 -08:00 committed by Andrew Morton
parent 37b338eed1
commit 927e926d72
1 changed files with 10 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

20
mm/userfaultfd.c
View File

@ -1290,8 +1290,8 @@ retry:
spin_unlock(src_ptl);
if (!locked) {
pte_unmap(&orig_src_pte);
pte_unmap(&orig_dst_pte);
pte_unmap(src_pte);
pte_unmap(dst_pte);
src_pte = dst_pte = NULL;
/* now we can block and wait */
folio_lock(src_folio);
@ -1307,8 +1307,8 @@ retry:
/* at this point we have src_folio locked */
if (folio_test_large(src_folio)) {
/* split_folio() can block */
pte_unmap(&orig_src_pte);
pte_unmap(&orig_dst_pte);
pte_unmap(src_pte);
pte_unmap(dst_pte);
src_pte = dst_pte = NULL;
err = split_folio(src_folio);
if (err)
@ -1333,8 +1333,8 @@ retry:
goto out;
}
if (!anon_vma_trylock_write(src_anon_vma)) {
pte_unmap(&orig_src_pte);
pte_unmap(&orig_dst_pte);
pte_unmap(src_pte);
pte_unmap(dst_pte);
src_pte = dst_pte = NULL;
/* now we can block and wait */
anon_vma_lock_write(src_anon_vma);
@ -1352,8 +1352,8 @@ retry:
entry = pte_to_swp_entry(orig_src_pte);
if (non_swap_entry(entry)) {
if (is_migration_entry(entry)) {
pte_unmap(&orig_src_pte);
pte_unmap(&orig_dst_pte);
pte_unmap(src_pte);
pte_unmap(dst_pte);
src_pte = dst_pte = NULL;
migration_entry_wait(mm, src_pmd, src_addr);
err = -EAGAIN;
@ -1396,8 +1396,8 @@ retry:
src_folio = folio;
src_folio_pte = orig_src_pte;
if (!folio_trylock(src_folio)) {
pte_unmap(&orig_src_pte);
pte_unmap(&orig_dst_pte);
pte_unmap(src_pte);
pte_unmap(dst_pte);
src_pte = dst_pte = NULL;
put_swap_device(si);
si = NULL;