Commit 53c99852 authored by Breno Leitao's avatar Breno Leitao Committed by Will Deacon
Browse files

arm64/gcs: Fix error handling in arch_set_shadow_stack_status() 



alloc_gcs() returns an error-encoded pointer on failure, which comes
from do_mmap(), not NULL.

The current NULL check fails to detect errors, which could lead to using
an invalid GCS address.

Use IS_ERR_VALUE() to properly detect errors, consistent with the
check in gcs_alloc_thread_stack().

Fixes: b57180c7 ("arm64/gcs: Implement shadow stack prctl() interface")
Reviewed-by: default avatarMark Brown <broonie@kernel.org>
Signed-off-by: default avatarBreno Leitao <leitao@debian.org>
Signed-off-by: default avatarWill Deacon <will@kernel.org>
parent bb0c99e0

arch/arm64/mm/gcs.c

+2 −2
Original line number Diff line number Diff line
@@ -199,8 +199,8 @@ int arch_set_shadow_stack_status(struct task_struct *task, unsigned long arg) 


		size = gcs_size(0);

		gcs = alloc_gcs(0, size);

		if (!gcs)

			return -ENOMEM;

		if (IS_ERR_VALUE(gcs))

			return gcs;



		task->thread.gcspr_el0 = gcs + size - sizeof(u64);

		task->thread.gcs_base = gcs;