From 52b73d511b27de1fde3dd075af5d90393a1cd97d Mon Sep 17 00:00:00 2001 From: Jeremi Piotrowski Date: Mon, 9 Jan 2023 17:11:32 +0100 Subject: bus/selinux: Move vsnprintf call to avoid va_list reuse In log_callback() the same va_list is reused for a call to vsnprintf and vsyslog. A va_list can't be reused in this manner, such use is undefined behavior that changes depending on glibc version. In current glibc versions a segfault can be observed from the callsite at bus/selinux.c:412. When trying to log a non-auditable event, the segfault happens in strlen inside vsyslog. Moving the call to vsnprintf closer to audit_log_user_avc_message (which is followed by a 'goto out') avoids the reuse and segfault. Signed-off-by: Jeremi Piotrowski --- bus/selinux.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) (limited to 'bus') diff --git a/bus/selinux.c b/bus/selinux.c index 359f69a7..16665f45 100644 --- a/bus/selinux.c +++ b/bus/selinux.c @@ -114,9 +114,6 @@ log_callback (int type, const char *fmt, ...) * syslog if OOM, like the equivalent AppArmor code does. */ char buf[PATH_MAX*2]; - /* FIXME: need to change this to show real user */ - vsnprintf(buf, sizeof(buf), fmt, ap); - switch (type) { case SELINUX_AVC: @@ -139,6 +136,8 @@ log_callback (int type, const char *fmt, ...) } if (audit_type > 0) { + /* FIXME: need to change this to show real user */ + vsnprintf(buf, sizeof(buf), fmt, ap); audit_log_user_avc_message(audit_fd, audit_type, buf, NULL, NULL, NULL, getuid()); goto out; -- cgit v1.2.1