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mm/migrate: fix do_pages_stat in compat mode

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For arrays with more than 16 entries, the old code would incorrectly
advance the pages pointer by 16 words instead of 16 compat_uptr_t.  Fix by
doing the pointer arithmetic inside get_compat_pages_array where pages32
is already a correctly-typed pointer.

Discovered while working on PostgreSQL 18's new NUMA introspection code.

Link: https://lkml.kernel.org/r/aGREU0XTB48w9CwN@msg.df7cb.de
Fixes: 5b1b561ba7 ("mm: simplify compat_sys_move_pages")
Signed-off-by: Christoph Berg <myon@debian.org>
Acked-by: David Hildenbrand <david@redhat.com>
Suggested-by: David Hildenbrand <david@redhat.com>
Reported-by: Bertrand Drouvot <bertranddrouvot.pg@gmail.com>
Reported-by: Tomas Vondra <tomas@vondra.me>
Closes: https://www.postgresql.org/message-id/flat/6342f601-77de-4ee0-8c2a-3deb50ceac5b%40vondra.me#86402e3d80c031788f5f55b42c459471
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Byungchul Park <byungchul@sk.com>
Cc: Gregory Price <gourry@gourry.net>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
Cc: Mathew Brost <matthew.brost@intel.com>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Christoph Berg 2025-06-24 16:44:27 +02:00 committed by Andrew Morton
parent bb1b5929b4
commit 10d04c26ab
1 changed files with 8 additions and 6 deletions
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14
mm/migrate.c
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@ -2399,6 +2399,7 @@ static void do_pages_stat_array(struct mm_struct *mm, unsigned long nr_pages,
static int get_compat_pages_array(const void __user *chunk_pages[],
const void __user * __user *pages,
unsigned long chunk_offset,
unsigned long chunk_nr)
{
compat_uptr_t __user *pages32 = (compat_uptr_t __user *)pages;
@ -2406,7 +2407,7 @@ static int get_compat_pages_array(const void __user *chunk_pages[],
int i;
for (i = 0; i < chunk_nr; i++) {
if (get_user(p, pages32 + i))
if (get_user(p, pages32 + chunk_offset + i))
return -EFAULT;
chunk_pages[i] = compat_ptr(p);
}
@ -2425,27 +2426,28 @@ static int do_pages_stat(struct mm_struct *mm, unsigned long nr_pages,
#define DO_PAGES_STAT_CHUNK_NR 16UL
const void __user *chunk_pages[DO_PAGES_STAT_CHUNK_NR];
int chunk_status[DO_PAGES_STAT_CHUNK_NR];
unsigned long chunk_offset = 0;
while (nr_pages) {
unsigned long chunk_nr = min(nr_pages, DO_PAGES_STAT_CHUNK_NR);
if (in_compat_syscall()) {
if (get_compat_pages_array(chunk_pages, pages,
chunk_nr))
chunk_offset, chunk_nr))
break;
} else {
if (copy_from_user(chunk_pages, pages,
if (copy_from_user(chunk_pages, pages + chunk_offset,
chunk_nr * sizeof(*chunk_pages)))
break;
}
do_pages_stat_array(mm, chunk_nr, chunk_pages, chunk_status);
if (copy_to_user(status, chunk_status, chunk_nr * sizeof(*status)))
if (copy_to_user(status + chunk_offset, chunk_status,
chunk_nr * sizeof(*status)))
break;
pages += chunk_nr;
status += chunk_nr;
chunk_offset += chunk_nr;
nr_pages -= chunk_nr;
}
return nr_pages ? -EFAULT : 0;