linux-kernel - [PATCH 3.19 093/123] PCI: Dont read past the end of sysfs "driver

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Date:	Tue, 24 Mar 2015 16:46:42 +0100
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, Sasha Levin <sasha.levin@...cle.com>,
	Bjorn Helgaas <bhelgaas@...gle.com>,
	Alex Williamson <alex.williamson@...hat.com>,
	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
	Alexander Graf <agraf@...e.de>
Subject: [PATCH 3.19 093/123] PCI: Dont read past the end of sysfs "driver_override" buffer

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

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

From: Sasha Levin <sasha.levin@...cle.com>

commit 4efe874aace57dba967624ce1c48322da2447b75 upstream.

When printing the driver_override parameter when it is 4095 and 4094 bytes
long, the printing code would access invalid memory because we need count+1
bytes for printing.

Fixes: 782a985d7af2 ("PCI: Introduce new device binding path using pci_dev.driver_override")
Signed-off-by: Sasha Levin <sasha.levin@...cle.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@...gle.com>
Acked-by: Alex Williamson <alex.williamson@...hat.com>
CC: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
CC: Alexander Graf <agraf@...e.de>
CC: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/pci/pci-sysfs.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

--- a/drivers/pci/pci-sysfs.c
+++ b/drivers/pci/pci-sysfs.c
@@ -521,7 +521,8 @@ static ssize_t driver_override_store(str
 	struct pci_dev *pdev = to_pci_dev(dev);
 	char *driver_override, *old = pdev->driver_override, *cp;
 
-	if (count > PATH_MAX)
+	/* We need to keep extra room for a newline */
+	if (count >= (PAGE_SIZE - 1))
 		return -EINVAL;
 
 	driver_override = kstrndup(buf, count, GFP_KERNEL);
@@ -549,7 +550,7 @@ static ssize_t driver_override_show(stru
 {
 	struct pci_dev *pdev = to_pci_dev(dev);
 
-	return sprintf(buf, "%s\n", pdev->driver_override);
+	return snprintf(buf, PAGE_SIZE, "%s\n", pdev->driver_override);
 }
 static DEVICE_ATTR_RW(driver_override);
 


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