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SubjectRe: [PATCH] try_module_get(THIS_MODULE) is bogus
On Fri, Feb 21, 2003 at 06:18:43PM -0500, Christoph Hellwig wrote:
> In most cases the fix is to add an struct module * member to the operations
> vector instead and manipulate the refcounts in the callers context.
>
> For the ALSA cases it was completly superflous (when will people get it that
> using an exported symbol will make it's module unloadable?..)

This one had a use after free bug.. Fixed version below.


--- 1.2/drivers/char/ipmi/ipmi_kcs_intf.c Tue Feb 18 19:31:36 2003
+++ edited/drivers/char/ipmi/ipmi_kcs_intf.c Fri Feb 21 19:45:45 2003
@@ -613,18 +613,6 @@
atomic_set(&kcs_info->req_events, 1);
}

-static int new_user(void *send_info)
-{
- if (!try_module_get(THIS_MODULE))
- return -EBUSY;
- return 0;
-}
-
-static void user_left(void *send_info)
-{
- module_put(THIS_MODULE);
-}
-
/* Call every 10 ms. */
#define KCS_TIMEOUT_TIME_USEC 10000
#define KCS_USEC_PER_JIFFY (1000000/HZ)
@@ -718,11 +706,10 @@

static struct ipmi_smi_handlers handlers =
{
- sender: sender,
- request_events: request_events,
- new_user: new_user,
- user_left: user_left,
- set_run_to_completion: set_run_to_completion
+ .owner = THIS_MODULE,
+ .sender = sender,
+ .request_events = request_events,
+ .set_run_to_completion = set_run_to_completion,
};

static unsigned char ipmi_kcs_dev_rev;
===== drivers/char/ipmi/ipmi_msghandler.c 1.1 vs edited =====
--- 1.1/drivers/char/ipmi/ipmi_msghandler.c Mon Jan 13 13:07:12 2003
+++ edited/drivers/char/ipmi/ipmi_msghandler.c Fri Feb 21 19:45:45 2003
@@ -485,13 +485,14 @@
new_user->intf = ipmi_interfaces[if_num];
new_user->gets_events = 0;

- rv = new_user->intf->handlers->new_user(new_user->intf->send_info);
- if (rv)
+ if (!try_module_get(new_user->intf->handlers->owner)) {
+ rv = -ENODEV;
goto out_unlock;
+ }

- write_lock_irqsave(&(new_user->intf->users_lock), flags);
- list_add_tail(&(new_user->link), &(new_user->intf->users));
- write_unlock_irqrestore(&(new_user->intf->users_lock), flags);
+ write_lock_irqsave(&new_user->intf->users_lock, flags);
+ list_add_tail(&new_user->link, &new_user->intf->users);
+ write_unlock_irqrestore(&new_user->intf->users_lock, flags);

out_unlock:
if (rv) {
@@ -563,12 +564,12 @@
unsigned long flags;

down_read(&interfaces_sem);
- write_lock_irqsave(&(intf->users_lock), flags);
+ write_lock_irqsave(&intf->users_lock, flags);
rv = ipmi_destroy_user_nolock(user);
if (!rv)
- intf->handlers->user_left(intf->send_info);
+ module_put(intf->handlers->owner);

- write_unlock_irqrestore(&(intf->users_lock), flags);
+ write_unlock_irqrestore(&intf->users_lock, flags);
up_read(&interfaces_sem);
return rv;
}
===== drivers/ieee1394/hosts.c 1.13 vs edited =====
--- 1.13/drivers/ieee1394/hosts.c Sat Feb 1 17:43:09 2003
+++ edited/drivers/ieee1394/hosts.c Fri Feb 21 19:45:45 2003
@@ -11,6 +11,7 @@
*/

#include <linux/config.h>
+#include <linux/module.h>
#include <linux/types.h>
#include <linux/list.h>
#include <linux/init.h>
@@ -69,8 +70,10 @@
spin_lock_irqsave(&hosts_lock, flags);
list_for_each(lh, &hosts) {
if (host == list_entry(lh, struct hpsb_host, host_list)) {
- if (host->driver->devctl(host, MODIFY_USAGE, 1)) {
- host->driver->devctl(host, MODIFY_USAGE, 1);
+ if (try_module_get(host->driver->owner)) {
+ /* we're doing this twice and don't seem
+ to undo it.. --hch */
+ (void)try_module_get(host->driver->owner);
host->refcount++;
retval = 1;
}
@@ -95,7 +98,7 @@
{
unsigned long flags;

- host->driver->devctl(host, MODIFY_USAGE, 0);
+ module_put(host->driver->owner);

spin_lock_irqsave(&hosts_lock, flags);
host->refcount--;
===== drivers/ieee1394/hosts.h 1.11 vs edited =====
--- 1.11/drivers/ieee1394/hosts.h Fri Jan 31 01:48:22 2003
+++ edited/drivers/ieee1394/hosts.h Fri Feb 21 19:45:45 2003
@@ -92,12 +92,6 @@
* Return void. */
CANCEL_REQUESTS,

- /* Decrease host usage count if arg == 0, increase otherwise. Return
- * 1 for success, 0 for failure. Increase usage may fail if the driver
- * is in the process of shutting itself down. Decrease usage can not
- * fail. */
- MODIFY_USAGE,
-
/* Start or stop receiving isochronous channel in arg. Return void.
* This acts as an optimization hint, hosts are not required not to
* listen on unrequested channels. */
@@ -147,6 +141,7 @@
};

struct hpsb_host_driver {
+ struct module *owner;
const char *name;

/* This function must store a pointer to the configuration ROM into the
===== drivers/ieee1394/ohci1394.c 1.19 vs edited =====
--- 1.19/drivers/ieee1394/ohci1394.c Sun Feb 2 08:01:36 2003
+++ edited/drivers/ieee1394/ohci1394.c Fri Feb 21 19:45:45 2003
@@ -966,16 +966,6 @@
dma_trm_reset(&ohci->at_resp_context);
break;

- case MODIFY_USAGE:
- if (arg) {
- if (try_module_get(THIS_MODULE))
- retval = 1;
- } else {
- module_put(THIS_MODULE);
- retval = 1;
- }
- break;
-
case ISO_LISTEN_CHANNEL:
{
u64 mask;
@@ -3202,6 +3192,7 @@
}

static struct hpsb_host_driver ohci1394_driver = {
+ .owner = THIS_MODULE,
.name = OHCI1394_DRIVER_NAME,
.get_rom = ohci_get_rom,
.transmit_packet = ohci_transmit,
===== drivers/ieee1394/pcilynx.c 1.24 vs edited =====
--- 1.24/drivers/ieee1394/pcilynx.c Tue Feb 11 00:00:08 2003
+++ edited/drivers/ieee1394/pcilynx.c Fri Feb 21 19:45:45 2003
@@ -801,17 +801,6 @@

break;

- case MODIFY_USAGE:
- if (arg) {
- if (try_module_get(THIS_MODULE))
- retval = 1;
- } else {
- module_put(THIS_MODULE);
- retval = 1;
- }
-
- break;
-
case ISO_LISTEN_CHANNEL:
spin_lock_irqsave(&lynx->iso_rcv.lock, flags);

@@ -1904,6 +1893,7 @@
};

static struct hpsb_host_driver lynx_driver = {
+ .owner = THIS_MODULE,
.name = PCILYNX_DRIVER_NAME,
.get_rom = get_lynx_rom,
.transmit_packet = lynx_transmit,
===== drivers/pci/hotplug.c 1.10 vs edited =====
--- 1.10/drivers/pci/hotplug.c Thu Feb 6 10:58:43 2003
+++ edited/drivers/pci/hotplug.c Fri Feb 21 19:43:17 2003
@@ -173,44 +173,6 @@
EXPORT_SYMBOL(pci_visit_dev);

/**
- * pci_is_dev_in_use - query devices' usage
- * @dev: PCI device to query
- *
- * Queries whether a given PCI device is in use by a driver or not.
- * Returns 1 if the device is in use, 0 if it is not.
- */
-int pci_is_dev_in_use(struct pci_dev *dev)
-{
- /*
- * dev->driver will be set if the device is in use by a new-style
- * driver -- otherwise, check the device's regions to see if any
- * driver has claimed them.
- */
-
- int i;
- int inuse = 0;
-
- if (dev->driver) {
- /* Assume driver feels responsible */
- return 1;
- }
-
- for (i = 0; !dev->driver && !inuse && (i < 6); i++) {
- if (!pci_resource_start(dev, i))
- continue;
- if (pci_resource_flags(dev, i) & IORESOURCE_IO) {
- inuse = check_region(pci_resource_start(dev, i),
- pci_resource_len(dev, i));
- } else if (pci_resource_flags(dev, i) & IORESOURCE_MEM) {
- inuse = check_mem_region(pci_resource_start(dev, i),
- pci_resource_len(dev, i));
- }
- }
- return inuse;
-}
-EXPORT_SYMBOL(pci_is_dev_in_use);
-
-/**
* pci_remove_device_safe - remove an unused hotplug device
* @dev: the device to remove
*
@@ -221,9 +183,8 @@
*/
int pci_remove_device_safe(struct pci_dev *dev)
{
- if (pci_is_dev_in_use(dev)) {
+ if (pci_dev_driver(dev))
return -EBUSY;
- }
pci_remove_device(dev);
return 0;
}
===== include/linux/ipmi_smi.h 1.1 vs edited =====
--- 1.1/include/linux/ipmi_smi.h Tue Nov 26 23:06:25 2002
+++ edited/include/linux/ipmi_smi.h Fri Feb 21 19:45:47 2003
@@ -78,6 +78,8 @@

struct ipmi_smi_handlers
{
+ struct module *owner;
+
/* Called to enqueue an SMI message to be sent. This
operation is not allowed to fail. If an error occurs, it
should report back the error in a received message. It may
@@ -92,15 +94,6 @@
/* Called by the upper layer to request that we try to get
events from the BMC we are attached to. */
void (*request_events)(void *send_info);
-
- /* Called when someone is using the interface, so the module can
- adjust it's use count. Return zero if successful, or an
- errno if not. */
- int (*new_user)(void *send_info);
-
- /* Called when someone is no longer using the interface, so the
- module can adjust it's use count. */
- void (*user_left)(void *send_info);

/* Called when the interface should go into "run to
completion" mode. If this call sets the value to true, the
===== include/linux/sunrpc/auth.h 1.7 vs edited =====
--- 1.7/include/linux/sunrpc/auth.h Sun Jan 12 22:40:31 2003
+++ edited/include/linux/sunrpc/auth.h Fri Feb 21 19:45:47 2003
@@ -84,6 +84,7 @@
* Client authentication ops
*/
struct rpc_authops {
+ struct module *owner;
rpc_authflavor_t au_flavor; /* flavor (RPC_AUTH_*) */
#ifdef RPC_DEBUG
char * au_name;
+++ edited/net/sunrpc/auth.c Fri Feb 21 22:12:30 2003
@@ -8,6 +8,7 @@

#include <linux/types.h>
#include <linux/sched.h>
+#include <linux/module.h>
#include <linux/slab.h>
#include <linux/errno.h>
#include <linux/socket.h>
@@ -65,6 +66,8 @@

if (flavor >= RPC_AUTH_MAXFLAVOR || !(ops = auth_flavors[flavor]))
return NULL;
+ if (!try_module_get(ops->owner))
+ return NULL;
clnt->cl_auth = ops->create(clnt, pseudoflavor);
return clnt->cl_auth;
}
@@ -73,6 +76,8 @@
rpcauth_destroy(struct rpc_auth *auth)
{
auth->au_ops->destroy(auth);
+ module_put(auth->au_ops->owner);
+ kfree(auth);
}

static spinlock_t rpc_credcache_lock = SPIN_LOCK_UNLOCKED;
===== net/sunrpc/auth_null.c 1.9 vs edited =====
--- 1.9/net/sunrpc/auth_null.c Sun Jan 12 22:40:13 2003
+++ edited/net/sunrpc/auth_null.c Fri Feb 21 22:12:51 2003
@@ -8,6 +8,7 @@

#include <linux/types.h>
#include <linux/socket.h>
+#include <linux/module.h>
#include <linux/in.h>
#include <linux/utsname.h>
#include <linux/sunrpc/clnt.h>
@@ -41,7 +42,6 @@
{
dprintk("RPC: destroying NULL authenticator %p\n", auth);
rpcauth_free_credcache(auth);
- kfree(auth);
}

/*
@@ -125,6 +125,7 @@
}

struct rpc_authops authnull_ops = {
+ .owner = THIS_MODULE,
.au_flavor = RPC_AUTH_NULL,
#ifdef RPC_DEBUG
.au_name = "NULL",
===== net/sunrpc/auth_unix.c 1.9 vs edited =====
--- 1.9/net/sunrpc/auth_unix.c Sun Jan 12 22:40:13 2003
+++ edited/net/sunrpc/auth_unix.c Fri Feb 21 22:12:35 2003
@@ -8,6 +8,7 @@

#include <linux/types.h>
#include <linux/sched.h>
+#include <linux/module.h>
#include <linux/socket.h>
#include <linux/in.h>
#include <linux/sunrpc/clnt.h>
@@ -60,7 +61,6 @@
{
dprintk("RPC: destroying UNIX authenticator %p\n", auth);
rpcauth_free_credcache(auth);
- kfree(auth);
}

static struct rpc_cred *
@@ -219,6 +219,7 @@
}

struct rpc_authops authunix_ops = {
+ .owner = THIS_MODULE,
.au_flavor = RPC_AUTH_UNIX,
#ifdef RPC_DEBUG
.au_name = "UNIX",
===== net/sunrpc/auth_gss/auth_gss.c 1.2 vs edited =====
--- 1.2/net/sunrpc/auth_gss/auth_gss.c Sun Jan 12 22:40:31 2003
+++ edited/net/sunrpc/auth_gss/auth_gss.c Fri Feb 21 22:13:20 2003
@@ -438,8 +438,6 @@
struct rpc_auth * auth;

dprintk("RPC: creating GSS authenticator for client %p\n",clnt);
- if (!try_module_get(THIS_MODULE))
- return NULL;
if (!(gss_auth = kmalloc(sizeof(*gss_auth), GFP_KERNEL)))
goto out_dec;
gss_auth->mech = gss_pseudoflavor_to_mech(flavor);
@@ -470,7 +468,6 @@
err_free:
kfree(gss_auth);
out_dec:
- module_put(THIS_MODULE);
return NULL;
}

@@ -485,9 +482,6 @@
rpc_unlink(gss_auth->path);

rpcauth_free_credcache(auth);
-
- kfree(auth);
- module_put(THIS_MODULE);
}

/* gss_destroy_cred (and gss_destroy_ctx) are used to clean up after failure
@@ -691,6 +685,7 @@
}

static struct rpc_authops authgss_ops = {
+ .owner = THIS_MODULE,
.au_flavor = RPC_AUTH_GSS,
#ifdef RPC_DEBUG
.au_name = "RPCSEC_GSS",
===== sound/pci/rme9652/hammerfall_mem.c 1.11 vs edited =====
--- 1.11/sound/pci/rme9652/hammerfall_mem.c Mon Jan 27 18:30:54 2003
+++ edited/sound/pci/rme9652/hammerfall_mem.c Fri Feb 21 19:45:47 2003
@@ -150,8 +150,6 @@
for (i = 0; i < NBUFS; i++) {
rbuf = &hammerfall_buffers[i];
if (rbuf->flags == HAMMERFALL_BUF_ALLOCATED) {
- if (! try_module_get(THIS_MODULE))
- return NULL;
rbuf->flags |= HAMMERFALL_BUF_USED;
rbuf->pci = pcidev;
*dmaaddr = rbuf->addr;
@@ -171,7 +169,6 @@
rbuf = &hammerfall_buffers[i];
if (rbuf->buf == addr && rbuf->pci == pcidev) {
rbuf->flags &= ~HAMMERFALL_BUF_USED;
- module_put(THIS_MODULE);
return;
}
}
-
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