From: Richard Guy Briggs <rgb@xxxxxxxxxx>
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@xxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Cc: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: Seiji Nishikawa <snishika@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
Fixes: 8432c7006297 ("audit: Simplify locking around untag_chunk()")
Signed-off-by: Richard Guy Briggs <rgb@xxxxxxxxxx>
Reviewed-by: Jan Kara <jack@xxxxxxx>
[PM: reformatted/cleaned-up the commit description]
Signed-off-by: Paul Moore <paul@xxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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 */
