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Groups > linux.kernel > #1295719

[PATCH v1 1/4] um: Fix ptrace GETREGS/SETREGS bugs

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This fix two related bugs:
* PTRACE_GETREGS doesn't get the right orig_ax (syscall) value
* PTRACE_SETREGS can't set the orig_ax value (erased by initial value)

Remove the now useless and error-prone get_syscall().

Signed-off-by: Mickaël Salaün <mic@digikod.net>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Kees Cook <keescook@chromium.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Will Drewry <wad@chromium.org>
Cc: Thomas Meyer <thomas@m3y3r.de>
Cc: Nicolas Iooss <nicolas.iooss_linux@m4x.org>
Cc: Anton Ivanov <aivanov@brocade.com>
Cc: linux-kernel@vger.kernel.org
Cc: user-mode-linux-devel@lists.sourceforge.net
Cc: user-mode-linux-user@lists.sourceforge.net
Cc: Meredydd Luff <meredydd@senatehouse.org>
Cc: David Drysdale <drysdale@google.com>
---
 arch/um/kernel/skas/syscall.c   | 7 ++++++-
 arch/um/os-Linux/skas/process.c | 7 -------
 2 files changed, 6 insertions(+), 8 deletions(-)

diff --git a/arch/um/kernel/skas/syscall.c b/arch/um/kernel/skas/syscall.c
index 1683b8e..65f0d1a 100644
--- a/arch/um/kernel/skas/syscall.c
+++ b/arch/um/kernel/skas/syscall.c
@@ -7,6 +7,7 @@
 #include <linux/ptrace.h>
 #include <kern_util.h>
 #include <sysdep/ptrace.h>
+#include <sysdep/ptrace_user.h>
 #include <sysdep/syscalls.h>
 #include <os.h>
 
@@ -16,12 +17,16 @@ void handle_syscall(struct uml_pt_regs *r)
 	long result;
 	int syscall;
 
+	/* Save the syscall register. */
+	UPT_SYSCALL_NR(r) = PT_SYSCALL_NR(r->gp);
+
 	if (syscall_trace_enter(regs)) {
 		result = -ENOSYS;
 		goto out;
 	}
 
-	syscall = get_syscall(r);
+	/* Get the syscall after being potentially updated with ptrace. */
+	syscall = UPT_SYSCALL_NR(r);
 
 	if ((syscall > __NR_syscall_max) || syscall < 0)
 		result = -ENOSYS;
diff --git a/arch/um/os-Linux/skas/process.c b/arch/um/os-Linux/skas/process.c
index b856c66..23025d6 100644
--- a/arch/um/os-Linux/skas/process.c
+++ b/arch/um/os-Linux/skas/process.c
@@ -172,13 +172,6 @@ static void handle_trap(int pid, struct uml_pt_regs *regs,
 	handle_syscall(regs);
 }
 
-int get_syscall(struct uml_pt_regs *regs)
-{
-	UPT_SYSCALL_NR(regs) = PT_SYSCALL_NR(regs->gp);
-
-	return UPT_SYSCALL_NR(regs);
-}
-
 extern char __syscall_stub_start[];
 
 static int userspace_tramp(void *stack)
-- 
2.6.4

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Thread

[PATCH v1 0/4] um: Add seccomp support Mickaël Salaün <mic@digikod.net> - 2015-12-21 01:10 +0100
  [PATCH v1 4/4] um: Add seccomp support Mickaël Salaün <mic@digikod.net> - 2015-12-21 01:20 +0100
  [PATCH v1 1/4] um: Fix ptrace GETREGS/SETREGS bugs Mickaël Salaün <mic@digikod.net> - 2015-12-21 01:20 +0100
    Re: [PATCH v1 1/4] um: Fix ptrace GETREGS/SETREGS bugs Richard Weinberger <richard@nod.at> - 2015-12-21 01:30 +0100
      Re: [PATCH v1 1/4] um: Fix ptrace GETREGS/SETREGS bugs Richard Weinberger <richard@nod.at> - 2015-12-21 10:00 +0100
      Re: [PATCH v1 1/4] um: Fix ptrace GETREGS/SETREGS bugs Richard Weinberger <richard@nod.at> - 2015-12-21 10:10 +0100
        Re: [PATCH v1 1/4] um: Fix ptrace GETREGS/SETREGS bugs Mickaël Salaün <mic@digikod.net> - 2015-12-21 10:30 +0100
          Re: [PATCH v1 1/4] um: Fix ptrace GETREGS/SETREGS bugs Richard Weinberger <richard@nod.at> - 2015-12-21 11:20 +0100
            Re: [PATCH v1 1/4] um: Fix ptrace GETREGS/SETREGS bugs Mickaël Salaün <mic@digikod.net> - 2015-12-21 21:00 +0100
      Re: [PATCH v1 1/4] um: Fix ptrace GETREGS/SETREGS bugs Mickaël Salaün <mic@digikod.net> - 2015-12-21 10:20 +0100
  [PATCH v1 2/4] selftests/seccomp: Remove the need for HAVE_ARCH_TRACEHOOK Mickaël Salaün <mic@digikod.net> - 2015-12-21 01:30 +0100
  [PATCH v1 3/4] um: Add full asm/syscall.h support Mickaël Salaün <mic@digikod.net> - 2015-12-21 01:30 +0100

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