diff options
| author |   Andrzej Pietrasiewicz <andrzej.p@samsung.com> | 2015-02-13 12:12:53 +0100 |
|---|---|---|
| committer |   Felipe Balbi <balbi@ti.com> | 2015-02-23 09:37:27 -0600 |
| commit | a0456399fb07155637a2b597b91cc1c63bc25141 (patch) | |
| tree | 787a0ea31a97dda853d6213dfedb77612a371c7f /drivers/usb | |
| parent | usb: dwc3: dwc3-omap: Fix disable IRQ (diff) | |
| download | linux-dev-a0456399fb07155637a2b597b91cc1c63bc25141.tar.xz linux-dev-a0456399fb07155637a2b597b91cc1c63bc25141.zip | |
usb: gadget: configfs: don't NUL-terminate (sub)compatible ids
The "Extended Compat ID OS Feature Descriptor Specification" does not
require the (sub)compatible ids to be NUL-terminated, because they
are placed in a fixed-size buffer and only unused parts of it should
contain NULs. If the buffer is fully utilized, there is no place for NULs.
Consequently, the code which uses desc->ext_compat_id never expects the
data contained to be NUL terminated.
If the compatible id is stored after sub-compatible id, and the compatible
id is full length (8 bytes), the (useless) NUL terminator overwrites the
first byte of the sub-compatible id.
If the sub-compatible id is full length (8 bytes), the (useless) NUL
terminator ends up out of the buffer. The situation can happen in the RNDIS
function, where the buffer is a part of struct f_rndis_opts. The next
member of struct f_rndis_opts is a mutex, so its first byte gets
overwritten. The said byte is a part of a mutex'es member which contains
the information on whether the muext is locked or not. This can lead to a
deadlock, because, in a configfs-composed gadget when a function is linked
into a configuration with config_usb_cfg_link(), usb_get_function()
is called, which then calls rndis_alloc(), which tries locking the same
mutex and (wrongly) finds it already locked.
This patch eliminates NUL terminating of the (sub)compatible id.
Cc: <stable@vger.kernel.org> # v3.16+
Fixes: da4243145fb1: "usb: gadget: configfs: OS Extended Compatibility descriptors support"
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Andrzej Pietrasiewicz <andrzej.p@samsung.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
Diffstat (limited to 'drivers/usb')
| -rw-r--r-- | drivers/usb/gadget/configfs.c | 2 |
1 files changed, 0 insertions, 2 deletions
diff --git a/drivers/usb/gadget/configfs.c b/drivers/usb/gadget/configfs.c index 75648145dc1b..c42765b3a060 100644 --- a/drivers/usb/gadget/configfs.c +++ b/drivers/usb/gadget/configfs.c @@ -1161,7 +1161,6 @@ static ssize_t interf_grp_compatible_id_store(struct usb_os_desc *desc, if (desc->opts_mutex) mutex_lock(desc->opts_mutex); memcpy(desc->ext_compat_id, page, l); - desc->ext_compat_id[l] = '\0'; if (desc->opts_mutex) mutex_unlock(desc->opts_mutex); @@ -1192,7 +1191,6 @@ static ssize_t interf_grp_sub_compatible_id_store(struct usb_os_desc *desc, if (desc->opts_mutex) mutex_lock(desc->opts_mutex); memcpy(desc->ext_compat_id + 8, page, l); - desc->ext_compat_id[l + 8] = '\0'; if (desc->opts_mutex) mutex_unlock(desc->opts_mutex); |