On Thu, Apr 03, 2025 at 10:37:17AM +0800, Xiaole He wrote: > Thank you for your feedback. > While I acknowledge your points, I would like to clarify the rationale > behind submitting this patch. > During my experimentation with an external module interacting with the > superblock, I utilized iterate_supers_type (from fs/super.c) as it is > an exported symbol. However, I observed a potential vulnerability in > its implementation: the type argument can be passed as NULL, leading > to a null pointer dereference. To verify this, I deliberately triggered > a scenario where type was set to NULL, resulting in the following dmesg > output: > After this observasion, I worry about if this vulnerability can cause > the whole kernel crash if the type argument is passed by a > unintentional NULL in the kernel code rather than in the external > module. > Thus I submitted the patch to address the missing null-check. > Thank you for your review. You do realize that passing it NULL as the second (function pointer) argument would also oops, right? Passing (void (*)(struct super_block *))kfree there would do even more unpleasant things, etc. Sure, it's exported - so's strlen(). While we are at it, checking just for NULL is not the limit - what if the caller gives it ERR_PTR(...) as argument?
