lkml.org 
[lkml]   [2011]   [Apr]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH] SMACK: Add missing rcu_read_lock/unlock for process capability walk.
Date
From: Andi Kleen <ak@linux.intel.com>

smk_access_entry does a RCU list walk for a list shared with other
threads. It relies on the caller doing rcu_read_lock().
One caller forgot to do to this, which could lead to races
on preemptible kernels.

Move the rcu_read_lock() into smk_access_entry instead.

Signed-off-by: Andi Kleen <ak@linux.intel.com>
---
security/smack/smack_access.c | 4 ++--
1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/security/smack/smack_access.c b/security/smack/smack_access.c
index 7b0d3b3..43b20f3 100644
--- a/security/smack/smack_access.c
+++ b/security/smack/smack_access.c
@@ -92,6 +92,7 @@ int smk_access_entry(char *subject_label, char *object_label,
int may = -ENOENT;
struct smack_rule *srp;

+ rcu_read_lock();
list_for_each_entry_rcu(srp, rule_list, list) {
if (srp->smk_subject == subject_label ||
strcmp(srp->smk_subject, subject_label) == 0) {
@@ -102,6 +103,7 @@ int smk_access_entry(char *subject_label, char *object_label,
}
}
}
+ rcu_read_unlock();

return may;
}
@@ -184,9 +186,7 @@ int smk_access_flags(char *subject_label, char *object_label, int request,
* good. A negative response from smk_access_entry()
* indicates there is no entry for this pair.
*/
- rcu_read_lock();
may = smk_access_entry(subject_label, object_label, &smack_rule_list);
- rcu_read_unlock();

if (may > 0 && (request & may) == request)
goto out_audit;
--
1.7.4.2


\
 
 \ /
  Last update: 2011-04-21 00:05    [W:0.207 / U:0.176 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site