linux-kernel - [tip: x86/entry] syscalls/x86: Fix function types in COND

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Message-ID: <157079292180.9978.16293404710090205910.tip-bot2@tip-bot2>
Date:   Fri, 11 Oct 2019 11:22:01 -0000
From:   "tip-bot2 for Sami Tolvanen" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Sami Tolvanen <samitolvanen@...gle.com>,
        Andy Lutomirski <luto@...nel.org>,
        Borislav Petkov <bp@...en8.de>,
        "H . Peter Anvin" <hpa@...or.com>,
        Kees Cook <keescook@...omium.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...nel.org>, linux-kernel@...r.kernel.org
Subject: [tip: x86/entry] syscalls/x86: Fix function types in COND_SYSCALL

The following commit has been merged into the x86/entry branch of tip:

Commit-ID:     6e4847640c6aebcaa2d9b3686cecc91b41f09269
Gitweb:        https://git.kernel.org/tip/6e4847640c6aebcaa2d9b3686cecc91b41f09269
Author:        Sami Tolvanen <samitolvanen@...gle.com>
AuthorDate:    Tue, 08 Oct 2019 15:40:49 -07:00
Committer:     Ingo Molnar <mingo@...nel.org>
CommitterDate: Fri, 11 Oct 2019 12:49:19 +02:00

syscalls/x86: Fix function types in COND_SYSCALL

Define a weak function in COND_SYSCALL instead of a weak alias to
sys_ni_syscall(), which has an incompatible type. This fixes indirect
call mismatches with Control-Flow Integrity (CFI) checking.

Signed-off-by: Sami Tolvanen <samitolvanen@...gle.com>
Acked-by: Andy Lutomirski <luto@...nel.org>
Cc: Borislav Petkov <bp@...en8.de>
Cc: H . Peter Anvin <hpa@...or.com>
Cc: Kees Cook <keescook@...omium.org>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Link: https://lkml.kernel.org/r/20191008224049.115427-6-samitolvanen@google.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 arch/x86/include/asm/syscall_wrapper.h | 21 ++++++++++++++++-----
 1 file changed, 16 insertions(+), 5 deletions(-)

diff --git a/arch/x86/include/asm/syscall_wrapper.h b/arch/x86/include/asm/syscall_wrapper.h
index 3dab048..e2389ce 100644
--- a/arch/x86/include/asm/syscall_wrapper.h
+++ b/arch/x86/include/asm/syscall_wrapper.h
@@ -6,6 +6,8 @@
 #ifndef _ASM_X86_SYSCALL_WRAPPER_H
 #define _ASM_X86_SYSCALL_WRAPPER_H
 
+struct pt_regs;
+
 /* Mapping of registers to parameters for syscalls on x86-64 and x32 */
 #define SC_X86_64_REGS_TO_ARGS(x, ...)					\
 	__MAP(x,__SC_ARGS						\
@@ -64,9 +66,15 @@
 	SYSCALL_ALIAS(__ia32_sys_##sname, __x64_sys_##sname);		\
 	asmlinkage long __x64_sys_##sname(const struct pt_regs *__unused)
 
-#define COND_SYSCALL(name)						\
-	cond_syscall(__x64_sys_##name);					\
-	cond_syscall(__ia32_sys_##name)
+#define COND_SYSCALL(name)							\
+	asmlinkage __weak long __x64_sys_##name(const struct pt_regs *__unused)	\
+	{									\
+		return sys_ni_syscall();					\
+	}									\
+	asmlinkage __weak long __ia32_sys_##name(const struct pt_regs *__unused)\
+	{									\
+		return sys_ni_syscall();					\
+	}
 
 #define SYS_NI(name)							\
 	SYSCALL_ALIAS(__x64_sys_##name, sys_ni_posix_timers);		\
@@ -218,7 +226,11 @@
 #endif
 
 #ifndef COND_SYSCALL
-#define COND_SYSCALL(name) cond_syscall(__x64_sys_##name)
+#define COND_SYSCALL(name) 							\
+	asmlinkage __weak long __x64_sys_##name(const struct pt_regs *__unused)	\
+	{									\
+		return sys_ni_syscall();					\
+	}
 #endif
 
 #ifndef SYS_NI
@@ -230,7 +242,6 @@
  * For VSYSCALLS, we need to declare these three syscalls with the new
  * pt_regs-based calling convention for in-kernel use.
  */
-struct pt_regs;
 asmlinkage long __x64_sys_getcpu(const struct pt_regs *regs);
 asmlinkage long __x64_sys_gettimeofday(const struct pt_regs *regs);
 asmlinkage long __x64_sys_time(const struct pt_regs *regs);