From: Arnd Bergmann <arnd@kernel.org>
To: linux-arch@vger.kernel.org
Cc: Arnd Bergmann <arnd@arndb.de>,
Alexander Viro <viro@zeniv.linux.org.uk>,
Andrew Morton <akpm@linux-foundation.org>,
Andy Lutomirski <luto@kernel.org>, Borislav Petkov <bp@alien8.de>,
Brian Gerst <brgerst@gmail.com>,
Christoph Hellwig <hch@infradead.org>,
Eric Biederman <ebiederm@xmission.com>,
Ingo Molnar <mingo@kernel.org>, "H . Peter Anvin" <hpa@zytor.com>,
Thomas Gleixner <tglx@linutronix.de>,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
kexec@lists.infradead.org
Subject: [PATCH v2 2/4] mm: simplify compat_sys_move_pages
Date: Mon, 2 Nov 2020 13:31:49 +0100 [thread overview]
Message-ID: <20201102123151.2860165-3-arnd@kernel.org> (raw)
In-Reply-To: <20201102123151.2860165-1-arnd@kernel.org>
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 5ca5842df5db..016e39809ca5 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1830,6 +1830,23 @@ 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.
@@ -1849,8 +1866,15 @@ 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);
@@ -1955,23 +1979,14 @@ 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 */
--
2.27.0
next prev parent reply other threads:[~2020-11-02 12:32 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-02 12:31 [PATCH v2 0/4] syscalls: remove compat_alloc_user_space callers Arnd Bergmann
2020-11-02 12:31 ` [PATCH v2 1/4] kexec: simplify compat_sys_kexec_load Arnd Bergmann
2020-11-03 8:35 ` Christoph Hellwig
2020-11-02 12:31 ` Arnd Bergmann [this message]
2020-11-03 8:36 ` [PATCH v2 2/4] mm: simplify compat_sys_move_pages Christoph Hellwig
2020-11-02 12:31 ` [PATCH v2 3/4] mm: simplify compat numa syscalls Arnd Bergmann
2020-11-02 12:31 ` [PATCH v2 4/4] compat: remove some compat entry points Arnd Bergmann
2020-11-03 8:37 ` Christoph Hellwig
2020-11-03 9:45 ` Arnd Bergmann
2020-12-08 15:06 ` Christoph Hellwig
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