The patch titled
uml: improve PTRACE_SYSEMU checking
has been added to the -mm tree. Its filename is
uml-improve-ptrace_sysemu-checking.patch
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: uml: improve PTRACE_SYSEMU checking
From: Jeff Dike <jdike@xxxxxxxxxxx>
Make the PTRACE_SYSEMU checking more robust. It will make sure that system
call numbers are reported correctly. If there is a problem, it will disable
PTRACE_SYSEMU use and use PTRACE_SYSCALL instead.
Thanks to Balaji G for helping reproduce this problem.
Signed-off-by: Jeff Dike <jdike@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/um/os-Linux/start_up.c | 24 ++++++++++++++++--------
1 file changed, 16 insertions(+), 8 deletions(-)
diff -puN arch/um/os-Linux/start_up.c~uml-improve-ptrace_sysemu-checking arch/um/os-Linux/start_up.c
--- a/arch/um/os-Linux/start_up.c~uml-improve-ptrace_sysemu-checking
+++ a/arch/um/os-Linux/start_up.c
@@ -144,9 +144,7 @@ static int stop_ptraced_child(int pid, v
int exit_with = WEXITSTATUS(status);
if (exit_with == 2)
non_fatal("check_ptrace : child exited with status 2. "
- "Serious trouble happening! Try updating "
- "your host skas patch!\nDisabling SYSEMU "
- "support.");
+ "\nDisabling SYSEMU support.\n");
non_fatal("check_ptrace : child exited with exitcode %d, while "
"expecting %d; status 0x%x\n", exit_with,
exitcode, status);
@@ -209,6 +207,7 @@ __uml_setup("nosysemu", nosysemu_cmd_par
static void __init check_sysemu(void)
{
void *stack;
+ unsigned long regs[MAX_REG_NR];
int pid, n, status, count=0;
non_fatal("Checking syscall emulation patch for ptrace...");
@@ -225,11 +224,20 @@ static void __init check_sysemu(void)
fatal("check_sysemu : expected SIGTRAP, got status = %d",
status);
- n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_RET_OFFSET,
- os_getpid());
- if(n < 0)
- fatal_perror("check_sysemu : failed to modify system call "
- "return");
+ if(ptrace(PTRACE_GETREGS, pid, 0, regs) < 0)
+ fatal_perror("check_sysemu : PTRACE_GETREGS failed");
+ if(PT_SYSCALL_NR(regs) != __NR_getpid){
+ non_fatal("check_sysemu got system call number %d, "
+ "expected %d...", PT_SYSCALL_NR(regs), __NR_getpid);
+ goto fail;
+ }
+
+ n = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_RET_OFFSET, os_getpid());
+ if(n < 0){
+ non_fatal("check_sysemu : failed to modify system call "
+ "return");
+ goto fail;
+ }
if (stop_ptraced_child(pid, stack, 0, 0) < 0)
goto fail_stopped;
_
Patches currently in -mm which might be from jdike@xxxxxxxxxxx are
uml-improve-ptrace_sysemu-checking.patch
uml-fix-ubd_add-error-reporting.patch
-
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