linux-kernel - [PATCH 3.19.y-ckt 055/170] quota: Fix possible GPF due to uninitialised pointers

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Message-Id: <1459558456-24452-56-git-send-email-kamal@canonical.com>
Date:	Fri,  1 Apr 2016 17:52:21 -0700
From:	Kamal Mostafa <kamal@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	Nikolay Borisov <kernel@...p.com>, Jan Kara <jack@...e.cz>,
	Kamal Mostafa <kamal@...onical.com>
Subject: [PATCH 3.19.y-ckt 055/170] quota: Fix possible GPF due to uninitialised pointers

3.19.8-ckt18 -stable review patch.  If anyone has any objections, please let me know.

---8<------------------------------------------------------------

From: Nikolay Borisov <kernel@...p.com>

commit ab73ef46398e2c0159f3a71de834586422d2a44a upstream.

When dqget() in __dquot_initialize() fails e.g. due to IO error,
__dquot_initialize() will pass an array of uninitialized pointers to
dqput_all() and thus can lead to deference of random data. Fix the
problem by properly initializing the array.

Signed-off-by: Nikolay Borisov <kernel@...p.com>
Signed-off-by: Jan Kara <jack@...e.cz>
[ kamal: backport to 3.19-stable: context ]
Signed-off-by: Kamal Mostafa <kamal@...onical.com>
---
 fs/quota/dquot.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/fs/quota/dquot.c b/fs/quota/dquot.c
index ca035a2..208ffd1 100644
--- a/fs/quota/dquot.c
+++ b/fs/quota/dquot.c
@@ -1389,7 +1389,7 @@ static int dquot_active(const struct inode *inode)
 static void __dquot_initialize(struct inode *inode, int type)
 {
 	int cnt, init_needed = 0;
-	struct dquot *got[MAXQUOTAS];
+	struct dquot *got[MAXQUOTAS] = {};
 	struct super_block *sb = inode->i_sb;
 	qsize_t rsv;
 
@@ -1399,7 +1399,6 @@ static void __dquot_initialize(struct inode *inode, int type)
 	/* First get references to structures we might need. */
 	for (cnt = 0; cnt < MAXQUOTAS; cnt++) {
 		struct kqid qid;
-		got[cnt] = NULL;
 		if (type != -1 && cnt != type)
 			continue;
 		/*
-- 
2.7.4