From: Mark Brown broonie@kernel.org
commit 05d881b85b48c7ac6a7c92ce00aa916c4a84d052 upstream.
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@kerne... Signed-off-by: Catalin Marinas catalin.marinas@arm.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- arch/arm64/kernel/fpsimd.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
--- a/arch/arm64/kernel/fpsimd.c +++ b/arch/arm64/kernel/fpsimd.c @@ -917,6 +917,8 @@ int vec_set_vector_length(struct task_st if (task == current) put_cpu_fpsimd_context();
+ task_set_vl(task, type, vl); + /* * Free the changed states if they are not in use, SME will be * reallocated to the correct size on next use and we just @@ -931,8 +933,6 @@ int vec_set_vector_length(struct task_st if (free_sme) sme_free(task);
- task_set_vl(task, type, vl); - out: update_tsk_thread_flag(task, vec_vl_inherit_flag(type), flags & PR_SVE_VL_INHERIT);