This is a note to let you know that I've just added the patch titled
mm/migrate: fix do_pages_move for compat pointers
to the 6.5-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
mm-migrate-fix-do_pages_move-for-compat-pointers.patch
and it can be found in the queue-6.5 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 229e2253766c7cdfe024f1fe280020cc4711087c Mon Sep 17 00:00:00 2001
From: Gregory Price <gourry.memverge@xxxxxxxxx>
Date: Tue, 3 Oct 2023 10:48:56 -0400
Subject: mm/migrate: fix do_pages_move for compat pointers
From: Gregory Price <gourry.memverge@xxxxxxxxx>
commit 229e2253766c7cdfe024f1fe280020cc4711087c upstream.
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@xxxxxxxxxxxx
Fixes: 5b1b561ba73c ("mm: simplify compat_sys_move_pages")
Signed-off-by: Gregory Price <gregory.price@xxxxxxxxxxxx>
Reported-by: Arnd Bergmann <arnd@xxxxxxxx>
Co-developed-by: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
mm/migrate.c | 14 ++++++++++++--
1 file changed, 12 insertions(+), 2 deletions(-)
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -2160,6 +2160,7 @@ 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;
@@ -2172,8 +2173,17 @@ 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 stable-queue which might be from gourry.memverge@xxxxxxxxx are
queue-6.5/mm-migrate-fix-do_pages_move-for-compat-pointers.patch
