lkml.org 
[lkml]   [2007]   [Jun]   [8]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    Date
    From
    Subject[patch 32/54] UML - Improve host PTRACE_SYSEMU check
    -stable review patch.  If anyone has any objections, please let us know.
    ---------------------

    From: Jeff Dike <jdike@addtoit.com>

    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.

    This fixes a hang on boot on FC6 hosts with a broken PTRACE_SYSEMU.

    Signed-off-by: Jeff Dike <jdike@linux.intel.com>
    Signed-off-by: Chris Wright <chrisw@sous-sol.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
    --
    arch/um/os-Linux/start_up.c | 24 ++++++++++++++++--------
    1 file changed, 16 insertions(+), 8 deletions(-)

    --- linux-2.6.21.4.orig/arch/um/os-Linux/start_up.c
    +++ linux-2.6.21.4/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;
    --
    -
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2007-06-08 09:53    [W:0.027 / U:0.300 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site