From: Peter Xu <peterx@redhat.com>
To: linux-kernel@vger.kernel.org,
Linus Torvalds <torvalds@linux-foundation.org>,
linux-mm@kvack.org
Cc: Andrew Morton <akpm@linux-foundation.org>,
peterx@redhat.com,
syzbot+693dc11fcb53120b5559@syzkaller.appspotmail.com
Subject: [PATCH 1/2] mm/mempolicy: Allow lookup_node() to handle fatal signal
Date: Tue, 7 Apr 2020 21:40:09 -0400 [thread overview]
Message-ID: <20200408014010.80428-2-peterx@redhat.com> (raw)
In-Reply-To: <20200408014010.80428-1-peterx@redhat.com>
lookup_node() uses gup to pin the page and get node information. It
checks against ret>=0 assuming the page will be filled in. However
it's also possible that gup will return zero, for example, when the
thread is quickly killed with a fatal signal. Teach lookup_node() to
gracefully return an error -EFAULT if it happens.
Meanwhile, initialize "page" to NULL to avoid potential risk of
exploiting the pointer.
Reported-by: syzbot+693dc11fcb53120b5559@syzkaller.appspotmail.com
Fixes: 4426e945df58 ("mm/gup: allow VM_FAULT_RETRY for multiple times")
Signed-off-by: Peter Xu <peterx@redhat.com>
---
mm/mempolicy.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 5fb427aed612..c7ca6a808fb1 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -897,12 +897,15 @@ static void get_policy_nodemask(struct mempolicy *p, nodemask_t *nodes)
static int lookup_node(struct mm_struct *mm, unsigned long addr)
{
- struct page *p;
+ struct page *p = NULL;
int err;
int locked = 1;
err = get_user_pages_locked(addr & PAGE_MASK, 1, 0, &p, &locked);
- if (err >= 0) {
+ if (err == 0) {
+ /* E.g. GUP interrupted by fatal signal */
+ err = -EFAULT;
+ } else if (err > 0) {
err = page_to_nid(p);
put_page(p);
}
--
2.24.1
next prev parent reply other threads:[~2020-04-08 1:40 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-08 1:40 [PATCH 0/2] mm: Two small fixes for recent syzbot reports Peter Xu
2020-04-08 1:40 ` Peter Xu [this message]
2020-04-08 10:21 ` [PATCH 1/2] mm/mempolicy: Allow lookup_node() to handle fatal signal Michal Hocko
2020-04-08 14:20 ` Peter Xu
2020-04-08 14:30 ` Michal Hocko
2020-04-08 15:24 ` Peter Xu
2020-04-08 15:26 ` Michal Hocko
2020-04-09 7:02 ` Michal Hocko
2020-04-09 12:52 ` Peter Xu
2020-04-09 13:00 ` Peter Xu
2020-04-09 13:53 ` Michal Hocko
2020-04-09 16:42 ` Linus Torvalds
2020-04-14 11:04 ` Michal Hocko
2020-04-14 13:49 ` Peter Xu
2020-04-14 14:18 ` Michal Hocko
2020-04-20 12:47 ` Michal Hocko
2020-04-20 17:31 ` Linus Torvalds
2020-04-21 7:09 ` Michal Hocko
2020-04-08 1:40 ` [PATCH 2/2] mm/gup: Mark lock taken only after a successful retake Peter Xu
2020-04-09 0:47 ` [PATCH 0/2] mm: Two small fixes for recent syzbot reports Andrew Morton
2020-04-09 11:49 ` Matthew Wilcox
2020-04-09 13:00 ` Dmitry Vyukov
2020-04-09 18:16 ` Andrew Morton
2020-04-09 18:53 ` Linus Torvalds
2020-04-09 19:12 ` Andrew Morton
2020-04-09 19:46 ` Linus Torvalds
2020-04-09 19:56 ` Matthew Wilcox
2020-04-09 19:58 ` Linus Torvalds
2020-04-09 20:27 ` Eric Biggers
2020-04-09 20:34 ` Linus Torvalds
2020-04-09 23:34 ` Stephen Rothwell
2020-04-10 1:11 ` Theodore Y. Ts'o
2020-04-09 12:55 ` Dmitry Vyukov
2020-04-09 16:32 ` Linus Torvalds
2020-04-09 16:58 ` Qian Cai
2020-04-09 17:05 ` Linus Torvalds
2020-04-09 17:58 ` Qian Cai
2020-04-09 18:06 ` Linus Torvalds
2020-04-09 21:14 ` Qian Cai
2020-04-10 13:12 ` Tetsuo Handa
2020-04-10 14:26 ` Qian Cai
2020-04-10 17:26 ` Andrew Morton
2020-04-10 19:46 ` Qian Cai
2020-04-09 23:29 ` Stephen Rothwell
2020-04-13 22:06 ` Qian Cai
2020-04-13 23:05 ` Jens Axboe
2020-04-14 11:12 ` Dmitry Vyukov
2020-04-14 11:59 ` Qian Cai
2020-04-14 12:05 ` Dmitry Vyukov
2020-04-14 19:28 ` Dan Rue
2020-04-15 11:09 ` Dmitry Vyukov
2020-04-15 16:23 ` Dan Rue
2020-04-16 0:34 ` Stephen Rothwell
2020-05-11 15:29 ` Dmitry Vyukov
2020-04-14 4:07 ` Hillf Danton
2020-04-14 4:31 ` Jens Axboe
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