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Date:   Thu, 31 Aug 2023 16:22:27 +0000
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Message-ID: <20230831162227.2307863-1-smostafa@google.com>
Subject: [PATCH] Revert "arm64/sysreg: refactor deprecated strncpy"
From:   Mostafa Saleh <smostafa@google.com>
To:     catalin.marinas@arm.com, will@kernel.org,
        linux-kernel@vger.kernel.org, kvmarm@lists.linux.dev,
        linux-arm-kernel@lists.infradead.org
Cc:     maz@kernel.org, oliver.upton@linux.dev, kristina.martsenko@arm.com,
        broonie@kernel.org, quic_pkondeti@quicinc.com, smostafa@google.com,
        justinstitt@google.com
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Precedence: bulk

This reverts commit d232606773a0b09ec7f1ffc25f63abe801d011fd.

Using strscpy is not correct in this context and the commit
assumption is not right "strncpy is deprecated for use on
NUL-terminated destination strings".

strncpy is used here to copy parts of the string(cmdline) separated
by spaces into the buffer and not a NULL terminated string.

This breaks the arm options "kvm-arm.mode=protected, arm64.nobti ..."

Signed-off-by: Mostafa Saleh <smostafa@google.com>
---
 arch/arm64/kernel/idreg-override.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/arch/arm64/kernel/idreg-override.c b/arch/arm64/kernel/idreg-override.c
index aee12c75b738..2fe2491b692c 100644
--- a/arch/arm64/kernel/idreg-override.c
+++ b/arch/arm64/kernel/idreg-override.c
@@ -262,9 +262,9 @@ static __init void __parse_cmdline(const char *cmdline, bool parse_aliases)
 		if (!len)
 			return;
 
-		len = strscpy(buf, cmdline, ARRAY_SIZE(buf));
-		if (len == -E2BIG)
-			len = ARRAY_SIZE(buf) - 1;
+		len = min(len, ARRAY_SIZE(buf) - 1);
+		strncpy(buf, cmdline, len);
+		buf[len] = 0;
 
 		if (strcmp(buf, "--") == 0)
 			return;
-- 
2.42.0.rc2.253.gd59a3bf2b4-goog