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H A D | vmem.c | 3e826100 Fri May 26 07:30:30 CDT 2023 Alexander Gordeev <agordeev@linux.ibm.com> s390/kasan: avoid short by one page shadow memory
Kernel Address Sanitizer uses 3 bits per byte to encode memory. That is the number of bits the start and end address of a memory range is shifted right when the corresponding shadow memory is created for that memory range.
The used memory mapping routine expects page-aligned addresses, while the above described 3-bit shift might turn the shadow memory range start and end boundaries into non-page-aligned in case the size of the original memory range is less than (PAGE_SIZE << 3). As result, the resulting shadow memory range could be short on one page.
Align on page boundary the start and end addresses when mapping a shadow memory range and avoid the described issue in the future.
Note, that does not fix a real problem, since currently no virtual regions of size less than (PAGE_SIZE << 3) exist.
Reviewed-by: Vasily Gorbik <gor@linux.ibm.com> Signed-off-by: Alexander Gordeev <agordeev@linux.ibm.com>
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