linux-kernel - [PATCH v3 3/7] um: Cleanup syscall_handler

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20220227184517.504931-4-keescook@chromium.org>
Date:   Sun, 27 Feb 2022 10:45:13 -0800
From:   Kees Cook <keescook@...omium.org>
To:     Kees Cook <keescook@...omium.org>
Cc:     David Gow <davidgow@...gle.com>,
        "Gustavo A. R. Silva" <gustavoars@...nel.org>,
        Nathan Chancellor <nathan@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Rasmus Villemoes <linux@...musvillemoes.dk>,
        Vitor Massaru Iha <vitor@...saru.org>,
        Daniel Latypov <dlatypov@...gle.com>,
        Anton Ivanov <anton.ivanov@...bridgegreys.com>,
        Jeff Dike <jdike@...toit.com>,
        Richard Weinberger <richard@....at>,
        Masahiro Yamada <masahiroy@...nel.org>,
        Arnd Bergmann <arnd@...db.de>, linux-kernel@...r.kernel.org,
        linux-um@...ts.infradead.org, linux-kbuild@...r.kernel.org,
        kunit-dev@...glegroups.com, llvm@...ts.linux.dev, x86@...nel.org,
        linux-hardening@...r.kernel.org
Subject: [PATCH v3 3/7] um: Cleanup syscall_handler_t definition/cast, fix warning

From: David Gow <davidgow@...gle.com>

The syscall_handler_t type for x86_64 was defined as 'long (*)(void)',
but always cast to 'long (*)(long, long, long, long, long, long)' before
use. This now triggers a warning (see below).

Define syscall_handler_t as the latter instead, and remove the cast.
This simplifies the code, and fixes the warning.

Warning:
In file included from ../arch/um/include/asm/processor-generic.h:13
                 from ../arch/x86/um/asm/processor.h:41
                 from ../include/linux/rcupdate.h:30
                 from ../include/linux/rculist.h:11
                 from ../include/linux/pid.h:5
                 from ../include/linux/sched.h:14
                 from ../include/linux/ptrace.h:6
                 from ../arch/um/kernel/skas/syscall.c:7:
../arch/um/kernel/skas/syscall.c: In function ‘handle_syscall’:
../arch/x86/um/shared/sysdep/syscalls_64.h:18:11: warning: cast between incompatible function types from ‘long int (*)(void)’ to ‘long int (*)(long int,  long int,  long int,  long int,  long int,  long int)’ [
-Wcast-function-type]
   18 |         (((long (*)(long, long, long, long, long, long)) \
      |           ^
../arch/x86/um/asm/ptrace.h:36:62: note: in definition of macro ‘PT_REGS_SET_SYSCALL_RETURN’
   36 | #define PT_REGS_SET_SYSCALL_RETURN(r, res) (PT_REGS_AX(r) = (res))
      |                                                              ^~~
../arch/um/kernel/skas/syscall.c:46:33: note: in expansion of macro ‘EXECUTE_SYSCALL’
   46 |                                 EXECUTE_SYSCALL(syscall, regs));
      |                                 ^~~~~~~~~~~~~~~

Signed-off-by: David Gow <davidgow@...gle.com>
Signed-off-by: Kees Cook <keescook@...omium.org>
Link: https://lore.kernel.org/r/20220210034353.1065703-1-davidgow@google.com
---
This is just a re-send of the above linked patch, collecting it into this series.
---
 arch/x86/um/shared/sysdep/syscalls_64.h | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/arch/x86/um/shared/sysdep/syscalls_64.h b/arch/x86/um/shared/sysdep/syscalls_64.h
index 48d6cd12f8a5..b6b997225841 100644
--- a/arch/x86/um/shared/sysdep/syscalls_64.h
+++ b/arch/x86/um/shared/sysdep/syscalls_64.h
@@ -10,13 +10,12 @@
 #include <linux/msg.h>
 #include <linux/shm.h>
 
-typedef long syscall_handler_t(void);
+typedef long syscall_handler_t(long, long, long, long, long, long);
 
 extern syscall_handler_t *sys_call_table[];
 
 #define EXECUTE_SYSCALL(syscall, regs) \
-	(((long (*)(long, long, long, long, long, long)) \
-	  (*sys_call_table[syscall]))(UPT_SYSCALL_ARG1(&regs->regs), \
+	(((*sys_call_table[syscall]))(UPT_SYSCALL_ARG1(&regs->regs), \
 		 		      UPT_SYSCALL_ARG2(&regs->regs), \
 				      UPT_SYSCALL_ARG3(&regs->regs), \
 				      UPT_SYSCALL_ARG4(&regs->regs), \
-- 
2.32.0