From: Eddie James <eajames@linux.ibm.com>
To: linux-fsi@lists.ozlabs.org
Cc: linux-kernel@vger.kernel.org, joel@jms.id.au,
alistair@popple.id.au, jk@ozlabs.org,
Eddie James <eajames@linux.ibm.com>
Subject: [PATCH] fsi: occ: Prevent use after free
Date: Thu, 12 May 2022 16:00:34 -0500 [thread overview]
Message-ID: <20220512210034.59907-1-eajames@linux.ibm.com> (raw)
Use get_device and put_device in the open and close functions to
make sure the device doesn't get freed while a file descriptor is
open.
Signed-off-by: Eddie James <eajames@linux.ibm.com>
---
drivers/fsi/fsi-occ.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/drivers/fsi/fsi-occ.c b/drivers/fsi/fsi-occ.c
index c9cc75fbdfb9..9e48dc62b1c5 100644
--- a/drivers/fsi/fsi-occ.c
+++ b/drivers/fsi/fsi-occ.c
@@ -82,6 +82,9 @@ static int occ_open(struct inode *inode, struct file *file)
struct miscdevice *mdev = file->private_data;
struct occ *occ = to_occ(mdev);
+ if (!occ->buffer)
+ return -ENOENT;
+
if (!client)
return -ENOMEM;
@@ -94,6 +97,7 @@ static int occ_open(struct inode *inode, struct file *file)
client->occ = occ;
mutex_init(&client->lock);
file->private_data = client;
+ get_device(occ->dev);
/* We allocate a 1-page buffer, make sure it all fits */
BUILD_BUG_ON((OCC_CMD_DATA_BYTES + 3) > PAGE_SIZE);
@@ -143,7 +147,7 @@ static ssize_t occ_write(struct file *file, const char __user *buf,
ssize_t rc;
u8 *cmd;
- if (!client)
+ if (!client || !client->occ->buffer)
return -ENODEV;
if (len > (OCC_CMD_DATA_BYTES + 3) || len < 3)
@@ -197,6 +201,7 @@ static int occ_release(struct inode *inode, struct file *file)
{
struct occ_client *client = file->private_data;
+ put_device(client->occ->dev);
free_page((unsigned long)client->buffer);
kfree(client);
@@ -672,6 +677,7 @@ static int occ_remove(struct platform_device *pdev)
struct occ *occ = platform_get_drvdata(pdev);
kvfree(occ->buffer);
+ occ->buffer = NULL;
misc_deregister(&occ->mdev);
--
2.27.0
next reply other threads:[~2022-05-12 21:01 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-05-12 21:00 Eddie James [this message]
2022-05-12 23:10 ` [PATCH] fsi: occ: Prevent use after free Guenter Roeck
2022-05-13 15:54 ` Eddie James
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20220512210034.59907-1-eajames@linux.ibm.com \
--to=eajames@linux.ibm.com \
--cc=alistair@popple.id.au \
--cc=jk@ozlabs.org \
--cc=joel@jms.id.au \
--cc=linux-fsi@lists.ozlabs.org \
--cc=linux-kernel@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).