| Message ID | 20220415085631.3613813-1-luomeng12@huawei.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | dm mpath: fix UAF in multipath_message() | expand |
friendly ping. 在 2022/4/15 16:56, Luo Meng 写道: > If dm_get_device() create dd in multipath_message(), > and then call table_deps() after dm_put_table_device(), > it will lead to concurrency UAF bugs. > > One of the concurrency UAF can be shown as below: > > (USE) | (FREE) > | target_message > | multipath_message > | dm_put_device > | dm_put_table_device # > | kfree(td) # table_device *td > ioctl # DM_TABLE_DEPS_CMD | ... > table_deps | ... > dm_get_live_or_inactive_table | ... > retrieve_dep | ... > list_for_each_entry | ... > deps->dev[count++] = | ... > huge_encode_dev | ... > (dd->dm_dev->bdev->bd_dev) | list_del(&dd->list) > | kfree(dd) # dm_dev_internal > > The root cause of UAF bugs is that find_device() failed in > dm_get_device() and will create dd and refcount set 1, kfree() > in dm_put_table() is not protected. When td, which there are > still pointers point to, is released, the concurrency UAF bug > will happen. > > This patch add a flag to determine whether to create a new dd. > > Fixes: 8215d6ec5fee(dm table: remove unused dm_get_device range parameters) > Signed-off-by: Luo Meng <luomeng12@huawei.com> > --- > drivers/md/dm-mpath.c | 2 +- > drivers/md/dm-table.c | 43 +++++++++++++++++++++-------------- > include/linux/device-mapper.h | 2 ++ > 3 files changed, 29 insertions(+), 18 deletions(-) > > diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c > index 6ed9d2731254..ad63d729ff81 100644 > --- a/drivers/md/dm-mpath.c > +++ b/drivers/md/dm-mpath.c > @@ -1995,7 +1995,7 @@ static int multipath_message(struct dm_target *ti, unsigned argc, char **argv, > goto out; > } > > - r = dm_get_device(ti, argv[1], dm_table_get_mode(ti->table), &dev); > + r = __dm_get_device(ti, argv[1], dm_table_get_mode(ti->table), &dev, false); > if (r) { > DMWARN("message: error getting device %s", > argv[1]); > diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c > index 03541cfc2317..9dbc0ba37ae6 100644 > --- a/drivers/md/dm-table.c > +++ b/drivers/md/dm-table.c > @@ -339,12 +339,8 @@ dev_t dm_get_dev_t(const char *path) > } > EXPORT_SYMBOL_GPL(dm_get_dev_t); > > -/* > - * Add a device to the list, or just increment the usage count if > - * it's already present. > - */ > -int dm_get_device(struct dm_target *ti, const char *path, fmode_t mode, > - struct dm_dev **result) > +int __dm_get_device(struct dm_target *ti, const char *path, fmode_t mode, > + struct dm_dev **result, bool create_dd) > { > int r; > dev_t dev; > @@ -368,19 +364,21 @@ int dm_get_device(struct dm_target *ti, const char *path, fmode_t mode, > > dd = find_device(&t->devices, dev); > if (!dd) { > - dd = kmalloc(sizeof(*dd), GFP_KERNEL); > - if (!dd) > - return -ENOMEM; > - > - if ((r = dm_get_table_device(t->md, dev, mode, &dd->dm_dev))) { > - kfree(dd); > - return r; > - } > + if (create_dd) { > + dd = kmalloc(sizeof(*dd), GFP_KERNEL); > + if (!dd) > + return -ENOMEM; > > - refcount_set(&dd->count, 1); > - list_add(&dd->list, &t->devices); > - goto out; > + if ((r = dm_get_table_device(t->md, dev, mode, &dd->dm_dev))) { > + kfree(dd); > + return r; > + } > > + refcount_set(&dd->count, 1); > + list_add(&dd->list, &t->devices); > + goto out; > + } else > + return -ENODEV; > } else if (dd->dm_dev->mode != (mode | dd->dm_dev->mode)) { > r = upgrade_mode(dd, mode, t->md); > if (r) > @@ -391,6 +389,17 @@ int dm_get_device(struct dm_target *ti, const char *path, fmode_t mode, > *result = dd->dm_dev; > return 0; > } > +EXPORT_SYMBOL(__dm_get_device); > + > +/* > + * Add a device to the list, or just increment the usage count if > + * it's already present. > + */ > +int dm_get_device(struct dm_target *ti, const char *path, fmode_t mode, > + struct dm_dev **result) > +{ > + return __dm_get_device(ti, path, mode, result, true); > +} > EXPORT_SYMBOL(dm_get_device); > > static int dm_set_device_limits(struct dm_target *ti, struct dm_dev *dev, > diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h > index c2a3758c4aaa..6ea542e18048 100644 > --- a/include/linux/device-mapper.h > +++ b/include/linux/device-mapper.h > @@ -168,6 +168,8 @@ dev_t dm_get_dev_t(const char *path); > int dm_get_device(struct dm_target *ti, const char *path, fmode_t mode, > struct dm_dev **result); > void dm_put_device(struct dm_target *ti, struct dm_dev *d); > +int __dm_get_device(struct dm_target *ti, const char *path, fmode_t mode, > + struct dm_dev **result, bool create_dd); > > /* > * Information about a target type > -- dm-devel mailing list dm-devel@redhat.com https://listman.redhat.com/mailman/listinfo/dm-devel
ping... 在 2022/4/15 16:56, Luo Meng 写道: > If dm_get_device() create dd in multipath_message(), > and then call table_deps() after dm_put_table_device(), > it will lead to concurrency UAF bugs. > > One of the concurrency UAF can be shown as below: > > (USE) | (FREE) > | target_message > | multipath_message > | dm_put_device > | dm_put_table_device # > | kfree(td) # table_device *td > ioctl # DM_TABLE_DEPS_CMD | ... > table_deps | ... > dm_get_live_or_inactive_table | ... > retrieve_dep | ... > list_for_each_entry | ... > deps->dev[count++] = | ... > huge_encode_dev | ... > (dd->dm_dev->bdev->bd_dev) | list_del(&dd->list) > | kfree(dd) # dm_dev_internal > > The root cause of UAF bugs is that find_device() failed in > dm_get_device() and will create dd and refcount set 1, kfree() > in dm_put_table() is not protected. When td, which there are > still pointers point to, is released, the concurrency UAF bug > will happen. > > This patch add a flag to determine whether to create a new dd. > > Fixes: 8215d6ec5fee(dm table: remove unused dm_get_device range parameters) > Signed-off-by: Luo Meng <luomeng12@huawei.com> > --- > drivers/md/dm-mpath.c | 2 +- > drivers/md/dm-table.c | 43 +++++++++++++++++++++-------------- > include/linux/device-mapper.h | 2 ++ > 3 files changed, 29 insertions(+), 18 deletions(-) > > diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c > index 6ed9d2731254..ad63d729ff81 100644 > --- a/drivers/md/dm-mpath.c > +++ b/drivers/md/dm-mpath.c > @@ -1995,7 +1995,7 @@ static int multipath_message(struct dm_target *ti, unsigned argc, char **argv, > goto out; > } > > - r = dm_get_device(ti, argv[1], dm_table_get_mode(ti->table), &dev); > + r = __dm_get_device(ti, argv[1], dm_table_get_mode(ti->table), &dev, false); > if (r) { > DMWARN("message: error getting device %s", > argv[1]); > diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c > index 03541cfc2317..9dbc0ba37ae6 100644 > --- a/drivers/md/dm-table.c > +++ b/drivers/md/dm-table.c > @@ -339,12 +339,8 @@ dev_t dm_get_dev_t(const char *path) > } > EXPORT_SYMBOL_GPL(dm_get_dev_t); > > -/* > - * Add a device to the list, or just increment the usage count if > - * it's already present. > - */ > -int dm_get_device(struct dm_target *ti, const char *path, fmode_t mode, > - struct dm_dev **result) > +int __dm_get_device(struct dm_target *ti, const char *path, fmode_t mode, > + struct dm_dev **result, bool create_dd) > { > int r; > dev_t dev; > @@ -368,19 +364,21 @@ int dm_get_device(struct dm_target *ti, const char *path, fmode_t mode, > > dd = find_device(&t->devices, dev); > if (!dd) { > - dd = kmalloc(sizeof(*dd), GFP_KERNEL); > - if (!dd) > - return -ENOMEM; > - > - if ((r = dm_get_table_device(t->md, dev, mode, &dd->dm_dev))) { > - kfree(dd); > - return r; > - } > + if (create_dd) { > + dd = kmalloc(sizeof(*dd), GFP_KERNEL); > + if (!dd) > + return -ENOMEM; > > - refcount_set(&dd->count, 1); > - list_add(&dd->list, &t->devices); > - goto out; > + if ((r = dm_get_table_device(t->md, dev, mode, &dd->dm_dev))) { > + kfree(dd); > + return r; > + } > > + refcount_set(&dd->count, 1); > + list_add(&dd->list, &t->devices); > + goto out; > + } else > + return -ENODEV; > } else if (dd->dm_dev->mode != (mode | dd->dm_dev->mode)) { > r = upgrade_mode(dd, mode, t->md); > if (r) > @@ -391,6 +389,17 @@ int dm_get_device(struct dm_target *ti, const char *path, fmode_t mode, > *result = dd->dm_dev; > return 0; > } > +EXPORT_SYMBOL(__dm_get_device); > + > +/* > + * Add a device to the list, or just increment the usage count if > + * it's already present. > + */ > +int dm_get_device(struct dm_target *ti, const char *path, fmode_t mode, > + struct dm_dev **result) > +{ > + return __dm_get_device(ti, path, mode, result, true); > +} > EXPORT_SYMBOL(dm_get_device); > > static int dm_set_device_limits(struct dm_target *ti, struct dm_dev *dev, > diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h > index c2a3758c4aaa..6ea542e18048 100644 > --- a/include/linux/device-mapper.h > +++ b/include/linux/device-mapper.h > @@ -168,6 +168,8 @@ dev_t dm_get_dev_t(const char *path); > int dm_get_device(struct dm_target *ti, const char *path, fmode_t mode, > struct dm_dev **result); > void dm_put_device(struct dm_target *ti, struct dm_dev *d); > +int __dm_get_device(struct dm_target *ti, const char *path, fmode_t mode, > + struct dm_dev **result, bool create_dd); > > /* > * Information about a target type > -- dm-devel mailing list dm-devel@redhat.com https://listman.redhat.com/mailman/listinfo/dm-devel
diff --git a/drivers/md/dm-mpath.c b/drivers/md/dm-mpath.c index 6ed9d2731254..ad63d729ff81 100644 --- a/drivers/md/dm-mpath.c +++ b/drivers/md/dm-mpath.c @@ -1995,7 +1995,7 @@ static int multipath_message(struct dm_target *ti, unsigned argc, char **argv, goto out; } - r = dm_get_device(ti, argv[1], dm_table_get_mode(ti->table), &dev); + r = __dm_get_device(ti, argv[1], dm_table_get_mode(ti->table), &dev, false); if (r) { DMWARN("message: error getting device %s", argv[1]); diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c index 03541cfc2317..9dbc0ba37ae6 100644 --- a/drivers/md/dm-table.c +++ b/drivers/md/dm-table.c @@ -339,12 +339,8 @@ dev_t dm_get_dev_t(const char *path) } EXPORT_SYMBOL_GPL(dm_get_dev_t); -/* - * Add a device to the list, or just increment the usage count if - * it's already present. - */ -int dm_get_device(struct dm_target *ti, const char *path, fmode_t mode, - struct dm_dev **result) +int __dm_get_device(struct dm_target *ti, const char *path, fmode_t mode, + struct dm_dev **result, bool create_dd) { int r; dev_t dev; @@ -368,19 +364,21 @@ int dm_get_device(struct dm_target *ti, const char *path, fmode_t mode, dd = find_device(&t->devices, dev); if (!dd) { - dd = kmalloc(sizeof(*dd), GFP_KERNEL); - if (!dd) - return -ENOMEM; - - if ((r = dm_get_table_device(t->md, dev, mode, &dd->dm_dev))) { - kfree(dd); - return r; - } + if (create_dd) { + dd = kmalloc(sizeof(*dd), GFP_KERNEL); + if (!dd) + return -ENOMEM; - refcount_set(&dd->count, 1); - list_add(&dd->list, &t->devices); - goto out; + if ((r = dm_get_table_device(t->md, dev, mode, &dd->dm_dev))) { + kfree(dd); + return r; + } + refcount_set(&dd->count, 1); + list_add(&dd->list, &t->devices); + goto out; + } else + return -ENODEV; } else if (dd->dm_dev->mode != (mode | dd->dm_dev->mode)) { r = upgrade_mode(dd, mode, t->md); if (r) @@ -391,6 +389,17 @@ int dm_get_device(struct dm_target *ti, const char *path, fmode_t mode, *result = dd->dm_dev; return 0; } +EXPORT_SYMBOL(__dm_get_device); + +/* + * Add a device to the list, or just increment the usage count if + * it's already present. + */ +int dm_get_device(struct dm_target *ti, const char *path, fmode_t mode, + struct dm_dev **result) +{ + return __dm_get_device(ti, path, mode, result, true); +} EXPORT_SYMBOL(dm_get_device); static int dm_set_device_limits(struct dm_target *ti, struct dm_dev *dev, diff --git a/include/linux/device-mapper.h b/include/linux/device-mapper.h index c2a3758c4aaa..6ea542e18048 100644 --- a/include/linux/device-mapper.h +++ b/include/linux/device-mapper.h @@ -168,6 +168,8 @@ dev_t dm_get_dev_t(const char *path); int dm_get_device(struct dm_target *ti, const char *path, fmode_t mode, struct dm_dev **result); void dm_put_device(struct dm_target *ti, struct dm_dev *d); +int __dm_get_device(struct dm_target *ti, const char *path, fmode_t mode, + struct dm_dev **result, bool create_dd); /* * Information about a target type
If dm_get_device() create dd in multipath_message(), and then call table_deps() after dm_put_table_device(), it will lead to concurrency UAF bugs. One of the concurrency UAF can be shown as below: (USE) | (FREE) | target_message | multipath_message | dm_put_device | dm_put_table_device # | kfree(td) # table_device *td ioctl # DM_TABLE_DEPS_CMD | ... table_deps | ... dm_get_live_or_inactive_table | ... retrieve_dep | ... list_for_each_entry | ... deps->dev[count++] = | ... huge_encode_dev | ... (dd->dm_dev->bdev->bd_dev) | list_del(&dd->list) | kfree(dd) # dm_dev_internal The root cause of UAF bugs is that find_device() failed in dm_get_device() and will create dd and refcount set 1, kfree() in dm_put_table() is not protected. When td, which there are still pointers point to, is released, the concurrency UAF bug will happen. This patch add a flag to determine whether to create a new dd. Fixes: 8215d6ec5fee(dm table: remove unused dm_get_device range parameters) Signed-off-by: Luo Meng <luomeng12@huawei.com> --- drivers/md/dm-mpath.c | 2 +- drivers/md/dm-table.c | 43 +++++++++++++++++++++-------------- include/linux/device-mapper.h | 2 ++ 3 files changed, 29 insertions(+), 18 deletions(-)