Messages in this thread Patch in this message | | | From | Eddie James <> | Subject | [PATCH] fsi: occ: Prevent use after free | Date | Thu, 12 May 2022 16:00:34 -0500 |
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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
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