[merged mm-hotfixes-stable] mm-migrate-fix-do_pages_move-for-compat-pointers.patch removed from -mm tree

[merged mm-hotfixes-stable] mm-migrate-fix-do_pages_move-for-compat-pointers.patch removed from -mm tree

[Andrew Morton]

The quilt patch titled
     Subject: mm/migrate: fix do_pages_move for compat pointers
has been removed from the -mm tree.  Its filename was
     mm-migrate-fix-do_pages_move-for-compat-pointers.patch

This patch was dropped because it was merged into the mm-hotfixes-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

------------------------------------------------------
From: Gregory Price <gourry.memverge@gmail.com>
Subject: mm/migrate: fix do_pages_move for compat pointers
Date: Tue, 3 Oct 2023 10:48:56 -0400

do_pages_move does not handle compat pointers for the page list. 
correctly.  Add in_compat_syscall check and appropriate get_user fetch
when iterating the page list.

It makes the syscall in compat mode (32-bit userspace, 64-bit kernel)
work the same way as the native 32-bit syscall again, restoring the
behavior before my broken commit 5b1b561ba73c ("mm: simplify
compat_sys_move_pages").

More specifically, my patch moved the parsing of the 'pages' array from
the main entry point into do_pages_stat(), which left the syscall
working correctly for the 'stat' operation (nodes = NULL), while the
'move' operation (nodes != NULL) is now missing the conversion and
interprets 'pages' as an array of 64-bit pointers instead of the
intended 32-bit userspace pointers.

It is possible that nobody noticed this bug because the few
applications that actually call move_pages are unlikely to run in
compat mode because of their large memory requirements, but this
clearly fixes a user-visible regression and should have been caught by
ltp.

Link: https://lkml.kernel.org/r/20231003144857.752952-1-gregory.price@memverge.com
Fixes: 5b1b561ba73c ("mm: simplify compat_sys_move_pages")
Signed-off-by: Gregory Price <gregory.price@memverge.com>
Reported-by: Arnd Bergmann <arnd@arndb.de>
Co-developed-by: Arnd Bergmann <arnd@arndb.de>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/migrate.c |   14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

--- a/mm/migrate.c~mm-migrate-fix-do_pages_move-for-compat-pointers
+++ a/mm/migrate.c
@@ -2162,6 +2162,7 @@ static int do_pages_move(struct mm_struc
 			 const int __user *nodes,
 			 int __user *status, int flags)
 {
+	compat_uptr_t __user *compat_pages = (void __user *)pages;
 	int current_node = NUMA_NO_NODE;
 	LIST_HEAD(pagelist);
 	int start, i;
@@ -2174,8 +2175,17 @@ static int do_pages_move(struct mm_struc
 		int node;
 
 		err = -EFAULT;
-		if (get_user(p, pages + i))
-			goto out_flush;
+		if (in_compat_syscall()) {
+			compat_uptr_t cp;
+
+			if (get_user(cp, compat_pages + i))
+				goto out_flush;
+
+			p = compat_ptr(cp);
+		} else {
+			if (get_user(p, pages + i))
+				goto out_flush;
+		}
 		if (get_user(node, nodes + i))
 			goto out_flush;
 
_

Patches currently in -mm which might be from gourry.memverge@gmail.com are

mm-migrate-remove-unused-mm-argument-from-do_move_pages_to_node.patch