If c->cdev->use_os_string flag is not set,
don't need to invoke ffs_do_os_descs() in _ffs_func_bind.
So uninitialized ext_compat_id pointer won't be accessed by
__ffs_func_bind_do_os_desc to cause kernel panic.

Signed-off-by: Jim Lin <ji...@nvidia.com>
---
 drivers/usb/gadget/function/f_fs.c | 18 ++++++++++--------
 1 file changed, 10 insertions(+), 8 deletions(-)

diff --git a/drivers/usb/gadget/function/f_fs.c 
b/drivers/usb/gadget/function/f_fs.c
index 15b648c..af3fdbd 100644
--- a/drivers/usb/gadget/function/f_fs.c
+++ b/drivers/usb/gadget/function/f_fs.c
@@ -2851,7 +2851,7 @@ static int _ffs_func_bind(struct usb_configuration *c,
                goto error;
 
        func->function.os_desc_table = vla_ptr(vlabuf, d, os_desc_table);
-       if (c->cdev->use_os_string)
+       if (c->cdev->use_os_string) {
                for (i = 0; i < ffs->interfaces_count; ++i) {
                        struct usb_os_desc *desc;
 
@@ -2862,13 +2862,15 @@ static int _ffs_func_bind(struct usb_configuration *c,
                                vla_ptr(vlabuf, d, ext_compat) + i * 16;
                        INIT_LIST_HEAD(&desc->ext_prop);
                }
-       ret = ffs_do_os_descs(ffs->ms_os_descs_count,
-                             vla_ptr(vlabuf, d, raw_descs) +
-                             fs_len + hs_len + ss_len,
-                             d_raw_descs__sz - fs_len - hs_len - ss_len,
-                             __ffs_func_bind_do_os_desc, func);
-       if (unlikely(ret < 0))
-               goto error;
+               ret = ffs_do_os_descs(ffs->ms_os_descs_count,
+                                     vla_ptr(vlabuf, d, raw_descs) +
+                                     fs_len + hs_len + ss_len,
+                                     d_raw_descs__sz - fs_len - hs_len -
+                                     ss_len,
+                                     __ffs_func_bind_do_os_desc, func);
+               if (unlikely(ret < 0))
+                       goto error;
+       }
        func->function.os_desc_n =
                c->cdev->use_os_string ? ffs->interfaces_count : 0;
 
-- 
1.9.1

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