of: module: add buffer overflow check in of_modalias()

[ Upstream commit cf7385cb ]

In of_modalias(), if the buffer happens to be too small even for the 1st
snprintf() call, the len parameter will become negative and str parameter
(if not NULL initially) will point beyond the buffer's end. Add the buffer
overflow check after the 1st snprintf() call and fix such check after the
strlen() call (accounting for the terminating NUL char).

Fixes: bc575064

 ("of/device: use of_property_for_each_string to parse compatible strings")
Signed-off-by: Sergey Shtylyov <s.shtylyov@omp.ru>
Link: https://lore.kernel.org/r/bbfc6be0-c687-62b6-d015-5141b93f313e@omp.ru
Signed-off-by: Rob Herring <robh@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

CVE: CVE-2024-38541
(xchen: Adapted the patch for context changes.)
Signed-off-by: Xiangyu Chen <xiangyu.chen@windriver.com>
Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com>