[Bug sanitizer/85230] asan: false positives in kernel on allocas

[dvyukov at google dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=85230

--- Comment #4 from Dmitry Vyukov <dvyukov at google dot com> ---
Removing these lines from runtime does not help unfortunately:

-       kasan_poison_shadow(left_redzone, KASAN_ALLOCA_REDZONE_SIZE,
-                     KASAN_ALLOCA_LEFT);

The right redzone is also somehow involved:

[   10.472896] Memory state around the buggy address:
[   10.473597]  ffff8800768aec80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00
[   10.474623]  ffff8800768aed00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00
[   10.475701] >ffff8800768aed80: 00 00 00 00 00 00 00 00 02 cb cb cb cb cb cb
cb
[   10.475706]                                                        ^
[   10.475716]  ffff8800768aee00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
00
[   10.478809]  ffff8800768aee80: 00 00 00 00 00 00 f1 f1 f1 f1 02 f2 f2 f2 f2
f2