[PATCH v3 2/4] mm: simplify compat_sys_move_pages
From: Arnd Bergmann <arnd@kernel.org>
Date: 2021-05-17 20:34:56
Also in:
kexec, linux-arch, linux-arm-kernel, lkml
Subsystem:
memory management, memory management - memory policy and migration, the rest · Maintainers:
Andrew Morton, David Hildenbrand, Linus Torvalds
From: Arnd Bergmann <arnd@arndb.de> The compat move_pages() implementation uses compat_alloc_user_space() for converting the pointer array. Moving the compat handling into the function itself is a bit simpler and lets us avoid the compat_alloc_user_space() call. Signed-off-by: Arnd Bergmann <arnd@arndb.de> --- mm/migrate.c | 45 ++++++++++++++++++++++++++++++--------------- 1 file changed, 30 insertions(+), 15 deletions(-)
diff --git a/mm/migrate.c b/mm/migrate.c
index b234c3f3acb7..a68d07f19a1a 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c@@ -1855,6 +1855,23 @@ static void do_pages_stat_array(struct mm_struct *mm, unsigned long nr_pages, mmap_read_unlock(mm); } +static int put_compat_pages_array(const void __user *chunk_pages[], + const void __user * __user *pages, + unsigned long chunk_nr) +{ + compat_uptr_t __user *pages32 = (compat_uptr_t __user *)pages; + compat_uptr_t p; + int i; + + for (i = 0; i < chunk_nr; i++) { + if (get_user(p, pages32 + i)) + return -EFAULT; + chunk_pages[i] = compat_ptr(p); + } + + return 0; +} + /* * Determine the nodes of a user array of pages and store it in * a user array of status.
@@ -1874,8 +1891,15 @@ static int do_pages_stat(struct mm_struct *mm, unsigned long nr_pages, if (chunk_nr > DO_PAGES_STAT_CHUNK_NR) chunk_nr = DO_PAGES_STAT_CHUNK_NR; - if (copy_from_user(chunk_pages, pages, chunk_nr * sizeof(*chunk_pages))) - break; + if (in_compat_syscall()) { + if (put_compat_pages_array(chunk_pages, pages, + chunk_nr)) + break; + } else { + if (copy_from_user(chunk_pages, pages, + chunk_nr * sizeof(*chunk_pages))) + break; + } do_pages_stat_array(mm, chunk_nr, chunk_pages, chunk_status);
@@ -1980,23 +2004,14 @@ SYSCALL_DEFINE6(move_pages, pid_t, pid, unsigned long, nr_pages, #ifdef CONFIG_COMPAT COMPAT_SYSCALL_DEFINE6(move_pages, pid_t, pid, compat_ulong_t, nr_pages, - compat_uptr_t __user *, pages32, + compat_uptr_t __user *, pages, const int __user *, nodes, int __user *, status, int, flags) { - const void __user * __user *pages; - int i; - - pages = compat_alloc_user_space(nr_pages * sizeof(void *)); - for (i = 0; i < nr_pages; i++) { - compat_uptr_t p; - - if (get_user(p, pages32 + i) || - put_user(compat_ptr(p), pages + i)) - return -EFAULT; - } - return kernel_move_pages(pid, nr_pages, pages, nodes, status, flags); + return kernel_move_pages(pid, nr_pages, + (const void __user *__user *)pages, + nodes, status, flags); } #endif /* CONFIG_COMPAT */
--
2.29.2