Re: [PATCH v4] kasan: add memory corruption identification for software tag-based mode

[Walter Wu]

On Tue, 2019-08-06 at 13:43 +0800, Walter Wu wrote:
> This patch adds memory corruption identification at bug report for
> software tag-based mode, the report show whether it is "use-after-free"
> or "out-of-bound" error instead of "invalid-access" error. This will make
> it easier for programmers to see the memory corruption problem.
> 
> We extend the slab to store five old free pointer tag and free backtrace,
> we can check if the tagged address is in the slab record and make a
> good guess if the object is more like "use-after-free" or "out-of-bound".
> therefore every slab memory corruption can be identified whether it's
> "use-after-free" or "out-of-bound".
> 
> ====== Changes
> Change since v1:
> - add feature option CONFIG_KASAN_SW_TAGS_IDENTIFY.
> - change QUARANTINE_FRACTION to reduce quarantine size.
> - change the qlist order in order to find the newest object in quarantine
> - reduce the number of calling kmalloc() from 2 to 1 time.
> - remove global variable to use argument to pass it.
> - correct the amount of qobject cache->size into the byes of qlist_head.
> - only use kasan_cache_shrink() to shink memory.
> 
> Change since v2:
> - remove the shinking memory function kasan_cache_shrink()
> - modify the description of the CONFIG_KASAN_SW_TAGS_IDENTIFY
> - optimize the quarantine_find_object() and qobject_free()
> - fix the duplicating function name 3 times in the header.
> - modify the function name set_track() to kasan_set_track()
> 
> Change since v3:
> - change tag-based quarantine to extend slab to identify memory corruption

Hi,Andrey,

Would you review the patch,please?
This patch is to pre-allocate slub record(tag and free backtrace) during
create slub object. When kernel has memory corruption, it will print
correct corruption type and free backtrace.

Thanks.

Walter