From patchwork Mon Mar 26 18:01:34 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: [Lucid,01/10] kmod: fix resource leak in call_usermodehelper_pipe() Date: Mon, 26 Mar 2012 08:01:34 -0000 From: Tim Gardner X-Patchwork-Id: 148789 Message-Id: <1332784903-75063-2-git-send-email-tim.gardner@canonical.com> To: kernel-team@lists.ubuntu.com From: Masami Hiramatsu BugLink: http://bugs.launchpad.net/bugs/963685 Fix resource (write-pipe file) leak in call_usermodehelper_pipe(). When call_usermodehelper_exec() fails, write-pipe file is opened and call_usermodehelper_pipe() just returns an error. Since it is hard for caller to determine whether the error occured when opening the pipe or executing the helper, the caller cannot close the pipe by themselves. I've found this resoruce leak when testing coredump. You can check how the resource leaks as below; $ echo "|nocommand" > /proc/sys/kernel/core_pattern $ ulimit -c unlimited $ while [ 1 ]; do ./segv; done &> /dev/null & $ cat /proc/meminfo (<- repeat it) where segv.c is; //----- int main () { char *p = 0; *p = 1; } //----- This patch closes write-pipe file if call_usermodehelper_exec() failed. Signed-off-by: Masami Hiramatsu Cc: Rusty Russell Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds (cherry picked from commit 8767ba2796a1c894e6d9524584a26a8224f0543d) Signed-off-by: Tim Gardner --- kernel/kmod.c | 12 +++++++----- 1 files changed, 7 insertions(+), 5 deletions(-) diff --git a/kernel/kmod.c b/kernel/kmod.c index a061472..9e38576 100644 --- a/kernel/kmod.c +++ b/kernel/kmod.c @@ -553,13 +553,15 @@ int call_usermodehelper_pipe(char *path, char **argv, char **envp, return -ENOMEM; ret = call_usermodehelper_stdinpipe(sub_info, filp); - if (ret < 0) - goto out; + if (ret < 0) { + call_usermodehelper_freeinfo(sub_info); + return ret; + } - return call_usermodehelper_exec(sub_info, UMH_WAIT_EXEC); + ret = call_usermodehelper_exec(sub_info, UMH_WAIT_EXEC); + if (ret < 0) /* Failed to execute helper, close pipe */ + filp_close(*filp, NULL); - out: - call_usermodehelper_freeinfo(sub_info); return ret; } EXPORT_SYMBOL(call_usermodehelper_pipe);