diff options
| author | Oleg Nesterov <oleg@redhat.com> | 2010-05-26 14:42:53 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2010-05-27 09:12:44 -0700 |
| commit | e0129ef91ed758c06b6557c36124acfb2e1c7305 (patch) | |
| tree | e47392371ed106f2241d18ac6339bedd6c699c9b | |
| parent | 9c1a125921d146f22cf28ff366ff69fd602a0e9b (diff) | |
| download | linux-e0129ef91ed758c06b6557c36124acfb2e1c7305.tar.bz2 | |
ptrace: PTRACE_GETFDPIC: fix the unsafe usage of child->mm
Now that Mike Frysinger unified the FDPIC ptrace code, we can fix the
unsafe usage of child->mm in ptrace_request(PTRACE_GETFDPIC).
We have the reference to task_struct, and ptrace_check_attach() verified
the tracee is stopped. But nothing can protect from SIGKILL after that,
we must not assume child->mm != NULL.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Mike Frysinger <vapier.adi@gmail.com>
Acked-by: David Howells <dhowells@redhat.com>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Greg Ungerer <gerg@snapgear.com>
Acked-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | kernel/ptrace.c | 10 |
1 files changed, 8 insertions, 2 deletions
diff --git a/kernel/ptrace.c b/kernel/ptrace.c index 4b4f72084d1b..74a3d693c196 100644 --- a/kernel/ptrace.c +++ b/kernel/ptrace.c @@ -596,18 +596,24 @@ int ptrace_request(struct task_struct *child, long request, #ifdef CONFIG_BINFMT_ELF_FDPIC case PTRACE_GETFDPIC: { + struct mm_struct *mm = get_task_mm(child); unsigned long tmp = 0; + ret = -ESRCH; + if (!mm) + break; + switch (addr) { case PTRACE_GETFDPIC_EXEC: - tmp = child->mm->context.exec_fdpic_loadmap; + tmp = mm->context.exec_fdpic_loadmap; break; case PTRACE_GETFDPIC_INTERP: - tmp = child->mm->context.interp_fdpic_loadmap; + tmp = mm->context.interp_fdpic_loadmap; break; default: break; } + mmput(mm); ret = put_user(tmp, (unsigned long __user *) data); break; |