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From: "Dmitry V. Levin" <ldv@altlinux.org>
To: Guo Ren <guoren@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>,
	Ingo Molnar <mingo@redhat.com>, Kees Cook <keescook@chromium.org>,
	Andy Lutomirski <luto@amacapital.net>,
	Will Drewry <wad@chromium.org>,
	linux-kernel@vger.kernel.org
Subject: [PATCH] csky: fix syscall_get_arguments() and syscall_set_arguments()
Date: Fri, 29 Mar 2019 20:12:30 +0300
Message-ID: <20190329171230.GB32456@altlinux.org> (raw)

C-SKY syscall arguments are located in orig_a0,a1,a2,a3,regs[0],regs[1]
fields of struct pt_regs.

Due to an off-by-one bug and a bug in pointer arithmetic
syscall_get_arguments() was reading orig_a0,regs[1..5] fields instead.
Likewise, syscall_set_arguments() was writing orig_a0,regs[1..5] fields
instead.

Fixes: 4859bfca11c7d ("csky: System Call")
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Will Drewry <wad@chromium.org>
Cc: stable@vger.kernel.org # v4.20+
Signed-off-by: Dmitry V. Levin <ldv@altlinux.org>
---
 arch/csky/include/asm/syscall.h | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/arch/csky/include/asm/syscall.h b/arch/csky/include/asm/syscall.h
index d637445737b7..9a9cd81e66c1 100644
--- a/arch/csky/include/asm/syscall.h
+++ b/arch/csky/include/asm/syscall.h
@@ -49,10 +49,11 @@ syscall_get_arguments(struct task_struct *task, struct pt_regs *regs,
 	if (i == 0) {
 		args[0] = regs->orig_a0;
 		args++;
-		i++;
 		n--;
+	} else {
+		i--;
 	}
-	memcpy(args, &regs->a1 + i * sizeof(regs->a1), n * sizeof(args[0]));
+	memcpy(args, &regs->a1 + i, n * sizeof(args[0]));
 }
 
 static inline void
@@ -63,10 +64,11 @@ syscall_set_arguments(struct task_struct *task, struct pt_regs *regs,
 	if (i == 0) {
 		regs->orig_a0 = args[0];
 		args++;
-		i++;
 		n--;
+	} else {
+		i--;
 	}
-	memcpy(&regs->a1 + i * sizeof(regs->a1), args, n * sizeof(regs->a0));
+	memcpy(&regs->a1 + i, args, n * sizeof(regs->a1));
 }
 
 static inline int
-- 
ldv

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Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-03-29 17:12 Dmitry V. Levin [this message]
2019-03-30  0:49 ` Guo Ren

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