diff options
| author | Eddie James <eajames@linux.ibm.com> | 2022-05-13 14:44:24 -0500 |
|---|---|---|
| committer | Joel Stanley <joel@jms.id.au> | 2022-09-28 21:10:57 +0930 |
| commit | d3e1e24604031b0d83b6c2d38f54eeea265cfcc0 (patch) | |
| tree | a439e95df47d7ad5d51a684b516705001b9a2c19 /drivers/fsi | |
| parent | dbed963ed62c4c2b8870a02c8b7dcb0c2af3ee0b (diff) | |
| download | lwn-d3e1e24604031b0d83b6c2d38f54eeea265cfcc0.tar.gz lwn-d3e1e24604031b0d83b6c2d38f54eeea265cfcc0.zip | |
fsi: occ: Prevent use after free
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.
Also, lock around the freeing of the device buffer and check the
buffer before using it in the submit function.
Signed-off-by: Eddie James <eajames@linux.ibm.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20220513194424.53468-1-eajames@linux.ibm.com
Signed-off-by: Joel Stanley <joel@jms.id.au>
Diffstat (limited to 'drivers/fsi')
| -rw-r--r-- | drivers/fsi/fsi-occ.c | 18 |
1 files changed, 15 insertions, 3 deletions
diff --git a/drivers/fsi/fsi-occ.c b/drivers/fsi/fsi-occ.c index 3d04e8baecbb..8f7f602b909d 100644 --- a/drivers/fsi/fsi-occ.c +++ b/drivers/fsi/fsi-occ.c @@ -94,6 +94,7 @@ 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); @@ -197,6 +198,7 @@ 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); @@ -493,12 +495,19 @@ int fsi_occ_submit(struct device *dev, const void *request, size_t req_len, for (i = 1; i < req_len - 2; ++i) checksum += byte_request[i]; - mutex_lock(&occ->occ_lock); + rc = mutex_lock_interruptible(&occ->occ_lock); + if (rc) + return rc; occ->client_buffer = response; occ->client_buffer_size = user_resp_len; occ->client_response_size = 0; + if (!occ->buffer) { + rc = -ENOENT; + goto done; + } + /* * Get a sequence number and update the counter. Avoid a sequence * number of 0 which would pass the response check below even if the @@ -674,10 +683,13 @@ static int occ_remove(struct platform_device *pdev) { struct occ *occ = platform_get_drvdata(pdev); - kvfree(occ->buffer); - misc_deregister(&occ->mdev); + mutex_lock(&occ->occ_lock); + kvfree(occ->buffer); + occ->buffer = NULL; + mutex_unlock(&occ->occ_lock); + device_for_each_child(&pdev->dev, NULL, occ_unregister_child); ida_simple_remove(&occ_ida, occ->idx); |