[PATCH] usb: gadget: f_mass_storage: fix null pointer dereference in fsg_common_set_num_buffers()

[Jeffin Philip]

On Mon, 17 Aug 2026 10:01:36 -0400, Alan Stern wrote:
>In fe5a6c48fd95 ("usb: gadget: storage: get rid of 
>fsg_num_buffers_validate()"), the code that was changed originally 
>required the number to lie between 2 and 32.  Even 1 was not acceptable.

Kconfig currently sets the limit from 2 to 256 with default as 2. However,
we use that only at build time. So, if we enter during runtime via configfs,
we set page content to 0\0 and get the null pointer dereference. So we will
need to add the check for num < 2 in fsg_opts_num_buffers_store() and return
EINVAL? Upper bound is 256 which is below what kstrtou8() can return anyway.

Thanks,
Jeffin.