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Yama: access task_struct->comm directly

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The core ptrace access checking routine holds a task lock, and when
reporting a failure, Yama takes a separate task lock. To avoid a
potential deadlock with two ptracers taking the opposite locks, do not
use get_task_comm() and just use ->comm directly since accuracy is not
important for the report.

Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Suggested-by: Oleg Nesterov <oleg@redhat.com>
CC: stable@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: John Johansen <john.johansen@canonical.com>
Signed-off-by: James Morris <james.l.morris@oracle.com>
This commit is contained in:
Kees Cook 2012-08-15 11:41:55 -07:00 committed by James Morris
parent d9875690d9
commit 7612bfeecc
1 changed files with 2 additions and 8 deletions
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10
security/yama/yama_lsm.c
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@ -279,12 +279,9 @@ static int yama_ptrace_access_check(struct task_struct *child,
}
if (rc) {
char name[sizeof(current->comm)];
printk_ratelimited(KERN_NOTICE
"ptrace of pid %d was attempted by: %s (pid %d)\n",
child->pid,
get_task_comm(name, current),
current->pid);
child->pid, current->comm, current->pid);
}
return rc;
@ -319,12 +316,9 @@ static int yama_ptrace_traceme(struct task_struct *parent)
}
if (rc) {
char name[sizeof(current->comm)];
printk_ratelimited(KERN_NOTICE
"ptraceme of pid %d was attempted by: %s (pid %d)\n",
current->pid,
get_task_comm(name, parent),
parent->pid);
current->pid, parent->comm, parent->pid);
}
return rc;