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authorPeter Xu <peterx@redhat.com>2020-04-08 04:40:10 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2020-04-08 05:34:31 +0300
commitc7b6a566b98524baea6a244186e665d22b633545 (patch)
tree00b778f01a2928b56a1221a1e291b06089ff8833
parentba841078cd0557b43b59c63f5c048b12168f0db2 (diff)
downloadlinux-c7b6a566b98524baea6a244186e665d22b633545.tar.xz
mm/gup: Mark lock taken only after a successful retake
It's definitely incorrect to mark the lock as taken even if down_read_killable() failed. This wass overlooked when we switched from down_read() to down_read_killable() because down_read() won't fail while down_read_killable() could. Fixes: 71335f37c5e8 ("mm/gup: allow to react to fatal signals") Reported-by: syzbot+a8c70b7f3579fc0587dc@syzkaller.appspotmail.com Signed-off-by: Peter Xu <peterx@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/gup.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/mm/gup.c b/mm/gup.c
index a21230569520..afce0bc47e70 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -1329,7 +1329,6 @@ retry:
if (fatal_signal_pending(current))
break;
- *locked = 1;
ret = down_read_killable(&mm->mmap_sem);
if (ret) {
BUG_ON(ret > 0);
@@ -1338,6 +1337,7 @@ retry:
break;
}
+ *locked = 1;
ret = __get_user_pages(tsk, mm, start, 1, flags | FOLL_TRIED,
pages, NULL, locked);
if (!*locked) {