Please pull this fix for a list corruption bug in the SELinux code.
This is an updated pull request after fixing the previously discussed git
repo issues.
---
The following changes since commit 0429fbc0bdc297d64188483ba029a23773ae07b0:
Merge branch 'for-3.18-consistent-ops' of
git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu (2014-10-15 07:48:18
+0200)
are available in the git repository at:
git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security.git
for-linus2
James Morris (1):
Merge branch 'stable-3.18' of
git://git.infradead.org/users/pcmoore/selinux into for-linus2
Stephen Smalley (1):
selinux: fix inode security list corruption
---
security/selinux/hooks.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
commit 9b32011acdc4428474b7cba865f713a11b9b9bd3
Merge: 0429fbc 923190d
Author: James Morris <[email protected]>
Date: Thu Oct 16 21:04:18 2014 +1100
Merge branch 'stable-3.18' of git://git.infradead.org/users/pcmoore/selinux
into for-linus2
commit 923190d32de4428afbea5e5773be86bea60a9925
Author: Stephen Smalley <[email protected]>
Date: Mon Oct 6 16:32:52 2014 -0400
selinux: fix inode security list corruption
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 <[email protected]>
Signed-off-by: Stephen Smalley <[email protected]>
Cc: [email protected]
Signed-off-by: Paul Moore <[email protected]>
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 29e64d4..2478976 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -481,6 +481,7 @@ 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) {
@@ -489,7 +490,6 @@ next_inode:
iput(inode);
}
spin_lock(&sbsec->isec_lock);
- list_del_init(&isec->list);
goto next_inode;
}
spin_unlock(&sbsec->isec_lock);
--
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