linux-kernel - [PATCH v2 1/6] arm64/signal: Don't redundantly verify FPSIMD magic

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Message-Id: <20221212-arm64-signal-cleanup-v2-1-14a8f3e088b7@kernel.org>
Date:   Tue, 03 Jan 2023 20:25:15 +0000
From:   Mark Brown <broonie@...nel.org>
To:     Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>
Cc:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Mark Brown <broonie@...nel.org>
Subject: [PATCH v2 1/6] arm64/signal: Don't redundantly verify FPSIMD magic

We validate that the magic in the struct fpsimd_context is correct in
restore_fpsimd_context() but this is redundant since parse_user_sigframe()
uses this magic to decide to call the function in the first place. Remove
the extra validation.

Signed-off-by: Mark Brown <broonie@...nel.org>
---
 arch/arm64/kernel/signal.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c
index e0d09bf5b01b..9d3d10269da7 100644
--- a/arch/arm64/kernel/signal.c
+++ b/arch/arm64/kernel/signal.c
@@ -189,15 +189,14 @@ static int preserve_fpsimd_context(struct fpsimd_context __user *ctx)
 static int restore_fpsimd_context(struct fpsimd_context __user *ctx)
 {
 	struct user_fpsimd_state fpsimd;
-	__u32 magic, size;
+	__u32 size;
 	int err = 0;
 
-	/* check the magic/size information */
-	__get_user_error(magic, &ctx->head.magic, err);
+	/* check the size information */
 	__get_user_error(size, &ctx->head.size, err);
 	if (err)
 		return -EFAULT;
-	if (magic != FPSIMD_MAGIC || size != sizeof(struct fpsimd_context))
+	if (size != sizeof(struct fpsimd_context))
 		return -EINVAL;
 
 	/* copy the FP and status/control registers */

-- 
2.30.2