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authorJeff Dike <jdike@addtoit.com>2007-05-23 13:57:40 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-05-23 20:14:12 -0700
commitcf6acedbeac17dea1c1eed85048a72e188f3f768 (patch)
treed5c1b4e5b9a5e8c22198bc92839c80305641cb09
parentda90fa8ff671a0139772ec3b3e82c06077e82122 (diff)
downloadlinux-2.6.34-ux500-cf6acedbeac17dea1c1eed85048a72e188f3f768.tar.gz
uml: improve PTRACE_SYSEMU checking
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@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--arch/um/os-Linux/start_up.c24
1 files changed, 16 insertions, 8 deletions
diff --git a/arch/um/os-Linux/start_up.c b/arch/um/os-Linux/start_up.c
index 79471f85eb8..3fc13fa8729 100644
--- a/arch/um/os-Linux/start_up.c
+++ b/arch/um/os-Linux/start_up.c
@@ -144,9 +144,7 @@ static int stop_ptraced_child(int pid, void *stack, int exitcode,
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_param,
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;