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SubjectPATCH] fix current->user->__count leak for processes
I am trying to test a patch for limiting maximum number of users on the
system(refer: [RFC][PATCH 2.5.70] Dynamically tunable maxusers, maxuprc
and max_pt_cnt on 06 Jun 2003).

I stumbled across this problem : when switch_uid is called,
the reference count of the new user is incremented twice. I think the
increment in the switch_uid is done because of the reparent_to_init()
function which does not increase the __count for root user.

But if switch_uid is called from any other function, the reference count
is already incremented by the caller by calling alloc_uid for the new
user. Hence the count is incremented twice. The user struct will not be
deleted even when there are no processes holding a reference count for
it. This does not cause any problem currently because nothing is
dependent on timely deletion of the user struct.

Here is a small patch to solve this problem.

Thanks and regards,

diff -Naur linux-2.5.73/kernel/exit.c linux-2.5.73.n/kernel/exit.c
--- linux-2.5.73/kernel/exit.c 2003-06-23 00:03:15.000000000 +0530
+++ linux-2.5.73.n/kernel/exit.c 2003-07-03 10:48:32.000000000 +0530
@@ -230,6 +230,7 @@
/* signals? */
memcpy(current->rlim, init_task.rlim, sizeof(*(current->rlim)));
+ atomic_inc(&(INIT_USER->__count));

diff -Naur linux-2.5.73/kernel/user.c linux-2.5.73.n/kernel/user.c
--- linux-2.5.73/kernel/user.c 2003-06-23 00:02:41.000000000 +0530
+++ linux-2.5.73.n/kernel/user.c 2003-07-03 10:46:59.000000000 +0530
@@ -126,7 +126,6 @@
* we should be checking for it. -DaveM
old_user = current->user;
- atomic_inc(&new_user->__count);
current->user = new_user;

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