Commit 10d04c26 authored by Christoph Berg's avatar Christoph Berg Committed by Andrew Morton
Browse files

mm/migrate: fix do_pages_stat in compat mode 

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: 5b1b561b ("mm: simplify compat_sys_move_pages")
Signed-off-by: default avatarChristoph Berg <myon@debian.org>
Acked-by: default avatarDavid Hildenbrand <david@redhat.com>
Suggested-by: default avatarDavid Hildenbrand <david@redhat.com>
Reported-by: default avatarBertrand Drouvot <bertranddrouvot.pg@gmail.com>
Reported-by: default avatarTomas 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: default avatarAndrew Morton <akpm@linux-foundation.org>
parent bb1b5929

mm/migrate.c

+8 −6
Original line number Diff line number Diff line
@@ -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;