linux-kernel - [PATCH] drivers/misc/sgi-gru: fix possible NULL dereference

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Date:	Thu, 10 Sep 2015 16:22:03 +0530
From:	Sudip Mukherjee <sudipm.mukherjee@...il.com>
To:	Dimitri Sivanich <sivanich@....com>, Arnd Bergmann <arnd@...db.de>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:	linux-kernel@...r.kernel.org,
	Sudip Mukherjee <sudipm.mukherjee@...il.com>
Subject: [PATCH] drivers/misc/sgi-gru: fix possible NULL dereference

If mmu_find_ops() returns NULL then we are allocating memory for gms
using kzalloc. But kzalloc can return NULL and we were dereferencing gms
in gru_dbg().

Signed-off-by: Sudip Mukherjee <sudip@...torindia.org>
---
 drivers/misc/sgi-gru/grutlbpurge.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/misc/sgi-gru/grutlbpurge.c b/drivers/misc/sgi-gru/grutlbpurge.c
index 2129274..757a8e9 100644
--- a/drivers/misc/sgi-gru/grutlbpurge.c
+++ b/drivers/misc/sgi-gru/grutlbpurge.c
@@ -317,8 +317,9 @@ struct gru_mm_struct *gru_register_mmu_notifier(void)
 				goto error;
 		}
 	}
-	gru_dbg(grudev, "gms %p, refcnt %d\n", gms,
-		atomic_read(&gms->ms_refcnt));
+	if (gms)
+		gru_dbg(grudev, "gms %p, refcnt %d\n", gms,
+			atomic_read(&gms->ms_refcnt));
 	return gms;
 error:
 	kfree(gms);
-- 
1.9.1

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