On Wed, Feb 09, 2022 at 03:22:35PM +0000, Joey Gouly wrote:
These can be used to place an MTE tag at an address that is not at a page size boundary.
The kernel prior to 295cf156231c ("arm64: Avoid premature usercopy failure"), would infinite loop if an MTE tag was placed not at a PAGE_SIZE boundary. This is because the kernel checked if the pages were readable by checking the first byte of each page, but would then fault in the middle of the page due to the MTE tag.
Signed-off-by: Joey Gouly joey.gouly@arm.com Cc: Catalin Marinas catalin.marinas@arm.com Cc: Will Deacon will@kernel.org Cc: Mark Brown broonie@kernel.org Cc: Shuah Khan shuah@kernel.org Reviewed-by: Mark Brown broonie@kernel.org Tested-by: Mark Brown broonie@kernel.org Reviewed-by: Shuah Khan skhan@linuxfoundation.org
Reviewed-by: Catalin Marinas catalin.marinas@arm.com