audit_syscall_exit() calls audit_get_context() which returns the tsk->audit_context but then also sets tsk->audit_context=NULL. A few lines later audit_syscall_exit sets the audit_context (either back to audit_context or to a different context) During this window when tsk->audit_context is NULL it is possible that another process will try to read /proc/pid/loginuid and will get a -1. There does not appear to be a good reason to set audit_context to null in the get function so this patch merely leaves the audit_context alone so there is no period of time in which audit_context is not pointing to a valid context. Signed-off-by: Eric Paris <eparis(a)redhat.com&gt; --- Easily tested, I opened 2 shells. shell #1 I read /proc/shell2/loginuid in a very very tight loop. shell #2 I ran a tight loop adding and removing audit rules without the patch I often saw -1 as the loginuid but with the patch I always got the correct behavior. kernel/auditsc.c | 5 +++-- 1 files changed, 3 insertions(+), 2 deletions(-) diff --git a/kernel/auditsc.c b/kernel/auditsc.c index 04f3ffb..62ace9b 100644 --- a/kernel/auditsc.c +++ b/kernel/auditsc.c @@ -598,7 +598,6 @@ static inline struct audit_context *audit_get_context(struct task_struct *tsk, get_context: - tsk->audit_context = NULL; return context; } @@ -1135,6 +1134,8 @@ void audit_free(struct task_struct *tsk) if (likely(!context)) return; + tsk->audit_context = NULL; + /* Check for system calls that do not go through the exit * function (e.g., exit_group), then free context block. * We use GFP_ATOMIC here because we might be doing this @@ -1266,9 +1267,9 @@ void audit_syscall_exit(int valid, long return_code) if (context->previous) { struct audit_context *new_context = context->previous; + tsk->audit_context = new_context; context->previous = NULL; audit_free_context(context); - tsk->audit_context = new_context; } else { audit_free_names(context); audit_free_aux(context);