linux-kernel - [PATCH 3.2 09/79] scsi: bfa: integer overflow in debugfs

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Message-ID: <lsq.1518322806.863275890@decadent.org.uk>
Date:   Sun, 11 Feb 2018 04:20:06 +0000
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        "Dan Carpenter" <dan.carpenter@...cle.com>
Subject: [PATCH 3.2 09/79] scsi: bfa: integer overflow in debugfs

3.2.99-rc1 review patch.  If anyone has any objections, please let me know.

------------------

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

commit 3e351275655d3c84dc28abf170def9786db5176d upstream.

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: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/scsi/bfa/bfad_debugfs.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

--- a/drivers/scsi/bfa/bfad_debugfs.c
+++ b/drivers/scsi/bfa/bfad_debugfs.c
@@ -276,7 +276,8 @@ bfad_debugfs_write_regrd(struct file *fi
 	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;
@@ -296,7 +297,7 @@ bfad_debugfs_write_regrd(struct file *fi
 	}
 
 	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__);