linux-kernel - [PATCH 02/10] signal/arm64: Better isolate the COMPAT_TASK portion of ptrace

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Date:   Tue, 23 Jan 2018 15:07:11 -0600
From:   "Eric W. Biederman" <ebiederm@...ssion.com>
To:     linux-kernel@...r.kernel.org
Cc:     Al Viro <viro@...iv.linux.org.uk>, Oleg Nesterov <oleg@...hat.com>,
        linux-arch@...r.kernel.org, Ram Pai <linuxram@...ibm.com>,
        "Eric W. Biederman" <ebiederm@...ssion.com>
Subject: [PATCH 02/10] signal/arm64: Better isolate the COMPAT_TASK portion of ptrace_hbptriggered

Instead of jumpping while !is_compat_task placee all of the code
inside of an if (is_compat_task) block.  This allows the int i
variable to be properly limited to the compat block no matter how the
rest of ptrace_hbptriggered changes.

In a following change a non-variable declaration will preceed
was made independent to ensure the code is easy to review.

Signed-off-by: "Eric W. Biederman" <ebiederm@...ssion.com>
---
 arch/arm64/kernel/ptrace.c | 27 ++++++++++++---------------
 1 file changed, 12 insertions(+), 15 deletions(-)

diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c
index 7c44658b316d..0a1cf830e4b3 100644
--- a/arch/arm64/kernel/ptrace.c
+++ b/arch/arm64/kernel/ptrace.c
@@ -188,26 +188,23 @@ static void ptrace_hbptriggered(struct perf_event *bp,
 	};
 
 #ifdef CONFIG_COMPAT
-	int i;
-
-	if (!is_compat_task())
-		goto send_sig;
+	if (is_compat_task()) {
+		int i;
 
-	for (i = 0; i < ARM_MAX_BRP; ++i) {
-		if (current->thread.debug.hbp_break[i] == bp) {
-			info.si_errno = (i << 1) + 1;
-			break;
+		for (i = 0; i < ARM_MAX_BRP; ++i) {
+			if (current->thread.debug.hbp_break[i] == bp) {
+				info.si_errno = (i << 1) + 1;
+				break;
+			}
 		}
-	}
 
-	for (i = 0; i < ARM_MAX_WRP; ++i) {
-		if (current->thread.debug.hbp_watch[i] == bp) {
-			info.si_errno = -((i << 1) + 1);
-			break;
+		for (i = 0; i < ARM_MAX_WRP; ++i) {
+			if (current->thread.debug.hbp_watch[i] == bp) {
+				info.si_errno = -((i << 1) + 1);
+				break;
+			}
 		}
 	}
-
-send_sig:
 #endif
 	force_sig_info(SIGTRAP, &info, current);
 }
-- 
2.14.1