All of lore.kernel.org
 help / color / mirror / Atom feed
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

WARNING: multiple messages have this Message-ID (diff)
From: Miles Chen <miles.chen@mediatek.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mm@kvack.org, Miles Chen <miles.chen@mediatek.com>,
	linux-mediatek@lists.infradead.org, linux-kernel@vger.kernel.org,
	wsd_upstream@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
_______________________________________________
Linux-mediatek mailing list
Linux-mediatek@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-mediatek

             reply	other threads:[~2020-04-07  9:51 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-07  9:51 Miles Chen [this message]
2020-04-07  9:51 ` [PATCH] mm/gup: fix null pointer dereference detected by coverity Miles Chen
2020-04-07 18:19 ` Ira Weiny
2020-04-07 18:19   ` Ira Weiny
2020-04-14 19:55   ` Souptick Joarder
2020-04-14 19:55     ` Souptick Joarder
2020-04-14 19:55     ` Souptick Joarder
2020-04-15  0:08 ` Andrew Morton
2020-04-15  0:08   ` Andrew Morton
2020-04-15  1:53   ` Miles Chen
2020-04-15  1:53     ` Miles Chen

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20200407095107.1988-1-miles.chen@mediatek.com \
    --to=miles.chen@mediatek.com \
    --cc=akpm@linux-foundation.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mediatek@lists.infradead.org \
    --cc=linux-mm@kvack.org \
    --cc=wsd_upstream@mediatek.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body. 
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.