From: Mark Brown <broonie@kernel.org>
Date: Mon, 15 Jan 2024 20:15:46 +0000 (+0000)
Subject: arm64/sme: Always exit sme_alloc() early with existing storage
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=dc7eb8755797ed41a0d1b5c0c39df3c8f401b3d9;p=linux.git

arm64/sme: Always exit sme_alloc() early with existing storage

When sme_alloc() is called with existing storage and we are not flushing we
will always allocate new storage, both leaking the existing storage and
corrupting the state. Fix this by separating the checks for flushing and
for existing storage as we do for SVE.

Callers that reallocate (eg, due to changing the vector length) should
call sme_free() themselves.

Fixes: 5d0a8d2fba50 ("arm64/ptrace: Ensure that SME is set up for target when writing SSVE state")
Signed-off-by: Mark Brown <broonie@kernel.org>
Cc: <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20240115-arm64-sme-flush-v1-1-7472bd3459b7@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
---

diff --git a/arch/arm64/kernel/fpsimd.c b/arch/arm64/kernel/fpsimd.c
index 0983be2b1b614..a5dc6f7641958 100644
--- a/arch/arm64/kernel/fpsimd.c
+++ b/arch/arm64/kernel/fpsimd.c
@@ -1217,8 +1217,10 @@ void fpsimd_release_task(struct task_struct *dead_task)
  */
 void sme_alloc(struct task_struct *task, bool flush)
 {
-	if (task->thread.sme_state && flush) {
-		memset(task->thread.sme_state, 0, sme_state_size(task));
+	if (task->thread.sme_state) {
+		if (flush)
+			memset(task->thread.sme_state, 0,
+			       sme_state_size(task));
 		return;
 	}