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From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	stable@vger.kernel.org, Jan Kara <jack@suse.cz>,
	Will Deacon <will@kernel.org>,
	Alexander Viro <viro@zeniv.linux.org.uk>,
	Seiji Nishikawa <snishika@redhat.com>,
	Richard Guy Briggs <rgb@redhat.com>,
	Paul Moore <paul@paul-moore.com>
Subject: [PATCH 5.14 11/11] audit: move put_tree() to avoid trim_trees refcount underflow and UAF
Date: Wed,  1 Sep 2021 14:29:19 +0200	[thread overview]
Message-ID: <20210901122249.884423913@linuxfoundation.org> (raw)
In-Reply-To: <20210901122249.520249736@linuxfoundation.org>

From: Richard Guy Briggs <rgb@redhat.com>

commit 67d69e9d1a6c889d98951c1d74b19332ce0565af upstream.

AUDIT_TRIM is expected to be idempotent, but multiple executions resulted
in a refcount underflow and use-after-free.

git bisect fingered commit fb041bb7c0a9	("locking/refcount: Consolidate
implementations of refcount_t") but this patch with its more thorough
checking that wasn't in the x86 assembly code merely exposed a previously
existing tree refcount imbalance in the case of tree trimming code that
was refactored with prune_one() to remove a tree introduced in
commit 8432c7006297 ("audit: Simplify locking around untag_chunk()")

Move the put_tree() to cover only the prune_one() case.

Passes audit-testsuite and 3 passes of "auditctl -t" with at least one
directory watch.

Cc: Jan Kara <jack@suse.cz>
Cc: Will Deacon <will@kernel.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Seiji Nishikawa <snishika@redhat.com>
Cc: stable@vger.kernel.org
Fixes: 8432c7006297 ("audit: Simplify locking around untag_chunk()")
Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
Reviewed-by: Jan Kara <jack@suse.cz>
[PM: reformatted/cleaned-up the commit description]
Signed-off-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 kernel/audit_tree.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/kernel/audit_tree.c
+++ b/kernel/audit_tree.c
@@ -593,7 +593,6 @@ static void prune_tree_chunks(struct aud
 		spin_lock(&hash_lock);
 	}
 	spin_unlock(&hash_lock);
-	put_tree(victim);
 }
 
 /*
@@ -602,6 +601,7 @@ static void prune_tree_chunks(struct aud
 static void prune_one(struct audit_tree *victim)
 {
 	prune_tree_chunks(victim, false);
+	put_tree(victim);
 }
 
 /* trim the uncommitted chunks from tree */



  parent reply	other threads:[~2021-09-01 12:55 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-01 12:29 [PATCH 5.14 00/11] 5.14.1-rc1 review Greg Kroah-Hartman
2021-09-01 12:29 ` [PATCH 5.14 01/11] vt_kdsetmode: extend console locking Greg Kroah-Hartman
2021-09-01 12:29 ` [PATCH 5.14 02/11] Bluetooth: btusb: check conditions before enabling USB ALT 3 for WBS Greg Kroah-Hartman
2021-09-01 12:29 ` [PATCH 5.14 03/11] net: dsa: mt7530: fix VLAN traffic leaks again Greg Kroah-Hartman
2021-09-01 12:29 ` [PATCH 5.14 04/11] btrfs: fix NULL pointer dereference when deleting device by invalid id Greg Kroah-Hartman
2021-09-01 12:29 ` [PATCH 5.14 05/11] Revert "floppy: reintroduce O_NDELAY fix" Greg Kroah-Hartman
2021-09-01 12:29 ` [PATCH 5.14 06/11] fscrypt: add fscrypt_symlink_getattr() for computing st_size Greg Kroah-Hartman
2021-09-01 12:29 ` [PATCH 5.14 07/11] ext4: report correct st_size for encrypted symlinks Greg Kroah-Hartman
2021-09-01 12:29 ` [PATCH 5.14 08/11] f2fs: " Greg Kroah-Hartman
2021-09-01 12:29 ` [PATCH 5.14 09/11] ubifs: " Greg Kroah-Hartman
2021-09-01 12:29 ` [PATCH 5.14 10/11] net: dont unconditionally copy_from_user a struct ifreq for socket ioctls Greg Kroah-Hartman
2021-09-01 12:29 ` Greg Kroah-Hartman [this message]
2021-09-01 19:04 ` [PATCH 5.14 00/11] 5.14.1-rc1 review Fox Chen
2021-09-01 21:20 ` Shuah Khan
2021-09-02  8:44 ` Naresh Kamboju
2021-09-02 21:51 ` Guenter Roeck
2021-09-02 23:58 ` Florian Fainelli

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