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authorStephen Smalley <sds@tycho.nsa.gov>2014-10-06 16:32:52 -0400
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-11-14 08:47:55 -0800
commite38e049b0eaa19affedf3be7f3b569ebe3b5e72b (patch)
treec787b4c6f529a9f75636380adb96a6646a591fd9 /security
parent1cde964e47f70c89e84618884a1258e325f9b856 (diff)
downloadlinux-linaro-stable-e38e049b0eaa19affedf3be7f3b569ebe3b5e72b.tar.gz
selinux: fix inode security list corruption
commit 923190d32de4428afbea5e5773be86bea60a9925 upstream. sb_finish_set_opts() can race with inode_free_security() when initializing inode security structures for inodes created prior to initial policy load or by the filesystem during ->mount(). This appears to have always been a possible race, but commit 3dc91d4 ("SELinux: Fix possible NULL pointer dereference in selinux_inode_permission()") made it more evident by immediately reusing the unioned list/rcu element of the inode security structure for call_rcu() upon an inode_free_security(). But the underlying issue was already present before that commit as a possible use-after-free of isec. Shivnandan Kumar reported the list corruption and proposed a patch to split the list and rcu elements out of the union as separate fields of the inode_security_struct so that setting the rcu element would not affect the list element. However, this would merely hide the issue and not truly fix the code. This patch instead moves up the deletion of the list entry prior to dropping the sbsec->isec_lock initially. Then, if the inode is dropped subsequently, there will be no further references to the isec. Reported-by: Shivnandan Kumar <shivnandan.k@samsung.com> Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov> Signed-off-by: Paul Moore <pmoore@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'security')
-rw-r--r--security/selinux/hooks.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 70d4a8a7f21c..fdd6e4f8be39 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -437,6 +437,7 @@ next_inode:
list_entry(sbsec->isec_head.next,
struct inode_security_struct, list);
struct inode *inode = isec->inode;
+ list_del_init(&isec->list);
spin_unlock(&sbsec->isec_lock);
inode = igrab(inode);
if (inode) {
@@ -445,7 +446,6 @@ next_inode:
iput(inode);
}
spin_lock(&sbsec->isec_lock);
- list_del_init(&isec->list);
goto next_inode;
}
spin_unlock(&sbsec->isec_lock);