From 53c998527ffa60f9deda8974a11ad39790684159 Mon Sep 17 00:00:00 2001 From: Breno Leitao Date: Mon, 2 Feb 2026 10:32:51 -0800 Subject: [PATCH] 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: b57180c75c7e ("arm64/gcs: Implement shadow stack prctl() interface") Reviewed-by: Mark Brown Signed-off-by: Breno Leitao Signed-off-by: Will Deacon --- arch/arm64/mm/gcs.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/arm64/mm/gcs.c b/arch/arm64/mm/gcs.c index 6e93f78de79b1..04a23a497f205 100644 --- a/arch/arm64/mm/gcs.c +++ b/arch/arm64/mm/gcs.c @@ -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; -- 2.47.3