From: Miles Chen <miles.chen@mediatek.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: <linux-mm@kvack.org>, <linux-kernel@vger.kernel.org>,
<linux-mediatek@lists.infradead.org>, <wsd_upstream@mediatek.com>,
Miles Chen <miles.chen@mediatek.com>
Subject: [PATCH] mm/gup: fix null pointer dereference detected by coverity
Date: Tue, 7 Apr 2020 17:51:07 +0800 [thread overview]
Message-ID: <20200407095107.1988-1-miles.chen@mediatek.com> (raw)
In fixup_user_fault(), it is possible that unlocked is NULL,
so we should test unlocked before using it.
For example, in arch/arc/kernel/process.c, NULL is passed
to fixup_user_fault().
SYSCALL_DEFINE3(arc_usr_cmpxchg, int *, uaddr, int, expected, int, new)
{
...
ret = fixup_user_fault(current, current->mm, (unsigned long) uaddr,
FAULT_FLAG_WRITE, NULL);
...
}
Fixes: 4a9e1cda2748 ("mm: bring in additional flag for fixup_user_fault to signal unlock")
Signed-off-by: Miles Chen <miles.chen@mediatek.com>
---
mm/gup.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/mm/gup.c b/mm/gup.c
index da3e03185144..a68d11dc232d 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -1230,7 +1230,8 @@ int fixup_user_fault(struct task_struct *tsk, struct mm_struct *mm,
if (ret & VM_FAULT_RETRY) {
down_read(&mm->mmap_sem);
if (!(fault_flags & FAULT_FLAG_TRIED)) {
- *unlocked = true;
+ if (unlocked)
+ *unlocked = true;
fault_flags |= FAULT_FLAG_TRIED;
goto retry;
}
--
2.18.0
next reply other threads:[~2020-04-07 9:51 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-07 9:51 Miles Chen [this message]
2020-04-07 18:19 ` [PATCH] mm/gup: fix null pointer dereference detected by coverity Ira Weiny
2020-04-14 19:55 ` Souptick Joarder
2020-04-15 0:08 ` Andrew Morton
2020-04-15 1:53 ` Miles Chen
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