linux-kernel - [PATCH AUTOSEL for 4.4 096/101] scsi: bfa: integer overflow in debugfs

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Message-ID: <20171207155005.5852-96-alexander.levin@verizon.com>
Date:   Thu, 7 Dec 2017 15:50:35 +0000
From:   alexander.levin@...izon.com
To:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>
Cc:     Dan Carpenter <dan.carpenter@...cle.com>,
        "Martin K . Petersen" <martin.petersen@...cle.com>,
        alexander.levin@...izon.com
Subject: [PATCH AUTOSEL for 4.4 096/101] scsi: bfa: integer overflow in
 debugfs

From: Dan Carpenter <dan.carpenter@...cle.com>

[ Upstream commit 3e351275655d3c84dc28abf170def9786db5176d ]

We could allocate less memory than intended because we do:

	bfad->regdata = kzalloc(len << 2, GFP_KERNEL);

The shift can overflow leading to a crash.  This is debugfs code so the
impact is very small.  I fixed the network version of this in March with
commit 13e2d5187f6b ("bna: integer overflow bug in debugfs").

Fixes: ab2a9ba189e8 ("[SCSI] bfa: add debugfs support")
Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>
Signed-off-by: Martin K. Petersen <martin.petersen@...cle.com>
Signed-off-by: Sasha Levin <alexander.levin@...izon.com>
---
 drivers/scsi/bfa/bfad_debugfs.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/scsi/bfa/bfad_debugfs.c b/drivers/scsi/bfa/bfad_debugfs.c
index 74a307c0a240..8f1c58d4d5b5 100644
--- a/drivers/scsi/bfa/bfad_debugfs.c
+++ b/drivers/scsi/bfa/bfad_debugfs.c
@@ -254,7 +254,8 @@ bfad_debugfs_write_regrd(struct file *file, const char __user *buf,
 	struct bfad_s *bfad = port->bfad;
 	struct bfa_s *bfa = &bfad->bfa;
 	struct bfa_ioc_s *ioc = &bfa->ioc;
-	int addr, len, rc, i;
+	int addr, rc, i;
+	u32 len;
 	u32 *regbuf;
 	void __iomem *rb, *reg_addr;
 	unsigned long flags;
@@ -265,7 +266,7 @@ bfad_debugfs_write_regrd(struct file *file, const char __user *buf,
 		return PTR_ERR(kern_buf);
 
 	rc = sscanf(kern_buf, "%x:%x", &addr, &len);
-	if (rc < 2) {
+	if (rc < 2 || len > (UINT_MAX >> 2)) {
 		printk(KERN_INFO
 			"bfad[%d]: %s failed to read user buf\n",
 			bfad->inst_no, __func__);
-- 
2.11.0