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Date: Mon, 21 Dec 2015 20:29:20 +0100
From: Mickaël Salaün <mic@...ikod.net>
To: linux-kernel@...r.kernel.org
Cc: Mickaël Salaün <mic@...ikod.net>,
Jonathan Corbet <corbet@....net>,
Jeff Dike <jdike@...toit.com>,
Richard Weinberger <richard@....at>,
Thomas Gleixner <tglx@...utronix.de>,
Ingo Molnar <mingo@...hat.com>,
"H . Peter Anvin" <hpa@...or.com>, x86@...nel.org,
Kees Cook <keescook@...omium.org>,
Andy Lutomirski <luto@...capital.net>,
Will Drewry <wad@...omium.org>,
Shuah Khan <shuahkh@....samsung.com>,
Chris Metcalf <cmetcalf@...hip.com>,
Michael Ellerman <mpe@...erman.id.au>,
Andrew Morton <akpm@...ux-foundation.org>,
James Hogan <james.hogan@...tec.com>,
Thomas Meyer <thomas@...3r.de>,
Nicolas Iooss <nicolas.iooss_linux@....org>,
Anton Ivanov <aivanov@...cade.com>, linux-doc@...r.kernel.org,
user-mode-linux-devel@...ts.sourceforge.net,
user-mode-linux-user@...ts.sourceforge.net,
linux-api@...r.kernel.org,
Meredydd Luff <meredydd@...atehouse.org>,
David Drysdale <drysdale@...gle.com>
Subject: [PATCH v2 1/4] um: Fix ptrace GETREGS/SETREGS bugs
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().
Fix inconsistent behavior in the ptrace implementation for i386 when
updating orig_eax automatically update the syscall number as well. This
is now updated in handle_syscall().
Signed-off-by: Mickaël Salaün <mic@...ikod.net>
Cc: Jeff Dike <jdike@...toit.com>
Cc: Richard Weinberger <richard@....at>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Kees Cook <keescook@...omium.org>
Cc: Andy Lutomirski <luto@...capital.net>
Cc: Will Drewry <wad@...omium.org>
Cc: Thomas Meyer <thomas@...3r.de>
Cc: Nicolas Iooss <nicolas.iooss_linux@....org>
Cc: Anton Ivanov <aivanov@...cade.com>
Cc: Meredydd Luff <meredydd@...atehouse.org>
Cc: David Drysdale <drysdale@...gle.com>
---
arch/um/kernel/skas/syscall.c | 25 ++++++++++++++-----------
arch/um/os-Linux/skas/process.c | 7 -------
arch/x86/um/ptrace_32.c | 8 +++-----
3 files changed, 17 insertions(+), 23 deletions(-)
diff --git a/arch/um/kernel/skas/syscall.c b/arch/um/kernel/skas/syscall.c
index 1683b8e..0d624e0 100644
--- a/arch/um/kernel/skas/syscall.c
+++ b/arch/um/kernel/skas/syscall.c
@@ -7,29 +7,32 @@
#include <linux/ptrace.h>
#include <kern_util.h>
#include <sysdep/ptrace.h>
+#include <sysdep/ptrace_user.h>
#include <sysdep/syscalls.h>
#include <os.h>
void handle_syscall(struct uml_pt_regs *r)
{
struct pt_regs *regs = container_of(r, struct pt_regs, regs);
- long result;
int syscall;
- if (syscall_trace_enter(regs)) {
- result = -ENOSYS;
+ /* Initialize the syscall number and default return value. */
+ UPT_SYSCALL_NR(r) = PT_SYSCALL_NR(r->gp);
+ PT_REGS_SET_SYSCALL_RETURN(regs, -ENOSYS);
+
+ if (syscall_trace_enter(regs))
goto out;
- }
- syscall = get_syscall(r);
+ /* Update the syscall number after orig_ax has potentially been updated
+ * with ptrace.
+ */
+ UPT_SYSCALL_NR(r) = PT_SYSCALL_NR(r->gp);
+ syscall = UPT_SYSCALL_NR(r);
- if ((syscall > __NR_syscall_max) || syscall < 0)
- result = -ENOSYS;
- else
- result = EXECUTE_SYSCALL(syscall, regs);
+ if (syscall >= 0 && syscall <= __NR_syscall_max)
+ PT_REGS_SET_SYSCALL_RETURN(regs,
+ EXECUTE_SYSCALL(syscall, regs));
out:
- PT_REGS_SET_SYSCALL_RETURN(regs, result);
-
syscall_trace_leave(regs);
}
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)
diff --git a/arch/x86/um/ptrace_32.c b/arch/x86/um/ptrace_32.c
index a29756f..47c78d5 100644
--- a/arch/x86/um/ptrace_32.c
+++ b/arch/x86/um/ptrace_32.c
@@ -68,6 +68,7 @@ static const int reg_offsets[] = {
[EFL] = HOST_EFLAGS,
[UESP] = HOST_SP,
[SS] = HOST_SS,
+ [ORIG_EAX] = HOST_ORIG_AX,
};
int putreg(struct task_struct *child, int regno, unsigned long value)
@@ -83,6 +84,7 @@ int putreg(struct task_struct *child, int regno, unsigned long value)
case EAX:
case EIP:
case UESP:
+ case ORIG_EAX:
break;
case FS:
if (value && (value & 3) != 3)
@@ -108,9 +110,6 @@ int putreg(struct task_struct *child, int regno, unsigned long value)
value &= FLAG_MASK;
child->thread.regs.regs.gp[HOST_EFLAGS] |= value;
return 0;
- case ORIG_EAX:
- child->thread.regs.regs.syscall = value;
- return 0;
default :
panic("Bad register in putreg() : %d\n", regno);
}
@@ -143,8 +142,6 @@ unsigned long getreg(struct task_struct *child, int regno)
regno >>= 2;
switch (regno) {
- case ORIG_EAX:
- return child->thread.regs.regs.syscall;
case FS:
case GS:
case DS:
@@ -163,6 +160,7 @@ unsigned long getreg(struct task_struct *child, int regno)
case EDI:
case EBP:
case EFL:
+ case ORIG_EAX:
break;
default:
panic("Bad register in getreg() : %d\n", regno);
--
2.6.4
--
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