diff options
| author | Eric W. Biederman <ebiederm@xmission.com> | 2022-04-29 09:23:55 -0500 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2022-06-09 10:20:49 +0200 |
| commit | b49516583f00e50ddd4fc5d1ec5726f5130543e5 (patch) | |
| tree | 99e17beac23f5ede5c4a2d9eb5a86e9f7f07527b /kernel | |
| parent | f8ef79687b2e156841b5758cc96e63796fd53542 (diff) | |
| download | linux-stable-b49516583f00e50ddd4fc5d1ec5726f5130543e5.tar.gz linux-stable-b49516583f00e50ddd4fc5d1ec5726f5130543e5.tar.bz2 linux-stable-b49516583f00e50ddd4fc5d1ec5726f5130543e5.zip | |
ptrace: Reimplement PTRACE_KILL by always sending SIGKILL
commit 6a2d90ba027adba528509ffa27097cffd3879257 upstream.
The current implementation of PTRACE_KILL is buggy and has been for
many years as it assumes it's target has stopped in ptrace_stop. At a
quick skim it looks like this assumption has existed since ptrace
support was added in linux v1.0.
While PTRACE_KILL has been deprecated we can not remove it as
a quick search with google code search reveals many existing
programs calling it.
When the ptracee is not stopped at ptrace_stop some fields would be
set that are ignored except in ptrace_stop. Making the userspace
visible behavior of PTRACE_KILL a noop in those case.
As the usual rules are not obeyed it is not clear what the
consequences are of calling PTRACE_KILL on a running process.
Presumably userspace does not do this as it achieves nothing.
Replace the implementation of PTRACE_KILL with a simple
send_sig_info(SIGKILL) followed by a return 0. This changes the
observable user space behavior only in that PTRACE_KILL on a process
not stopped in ptrace_stop will also kill it. As that has always
been the intent of the code this seems like a reasonable change.
Cc: stable@vger.kernel.org
Reported-by: Al Viro <viro@zeniv.linux.org.uk>
Suggested-by: Al Viro <viro@zeniv.linux.org.uk>
Tested-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Link: https://lkml.kernel.org/r/20220505182645.497868-7-ebiederm@xmission.com
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/ptrace.c | 5 |
1 files changed, 2 insertions, 3 deletions
diff --git a/kernel/ptrace.c b/kernel/ptrace.c index d99f73f83bf5..aab480e24bd6 100644 --- a/kernel/ptrace.c +++ b/kernel/ptrace.c @@ -1219,9 +1219,8 @@ int ptrace_request(struct task_struct *child, long request, return ptrace_resume(child, request, data); case PTRACE_KILL: - if (child->exit_state) /* already dead */ - return 0; - return ptrace_resume(child, request, SIGKILL); + send_sig_info(SIGKILL, SEND_SIG_NOINFO, child); + return 0; #ifdef CONFIG_HAVE_ARCH_TRACEHOOK case PTRACE_GETREGSET: |