arm64/sme: Set new vector length before reallocating
authorMark Brown <broonie@kernel.org>
Wed, 26 Jul 2023 12:12:26 +0000 (13:12 +0100)
committerCatalin Marinas <catalin.marinas@arm.com>
Wed, 26 Jul 2023 17:34:00 +0000 (18:34 +0100)
commit05d881b85b48c7ac6a7c92ce00aa916c4a84d052
tree5906e951e21b457cce12bf57a0cb1a2dafd6a6f8
parent3421ddbe6d64e55b76a67d57cef9e950b3d873ba
arm64/sme: Set new vector length before reallocating

As part of fixing the allocation of the buffer for SVE state when changing
SME vector length we introduced an immediate reallocation of the SVE state,
this is also done when changing the SVE vector length for consistency.
Unfortunately this reallocation is done prior to writing the new vector
length to the task struct, meaning the allocation is done with the old
vector length and can lead to memory corruption due to an undersized buffer
being used.

Move the update of the vector length before the allocation to ensure that
the new vector length is taken into account.

For some reason this isn't triggering any problems when running tests on
the arm64 fixes branch (even after repeated tries) but is triggering
issues very often after merge into mainline.

Fixes: d4d5be94a878 ("arm64/fpsimd: Ensure SME storage is allocated after SVE VL changes")
Signed-off-by: Mark Brown <broonie@kernel.org>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20230726-arm64-fix-sme-fix-v1-1-7752ec58af27@kernel.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
arch/arm64/kernel/fpsimd.c