From: Richard Guy Briggs <rgb@redhat.com> mainline inclusion from mainline-5.10.62 commit 38c1915d3e9f457006c4b2ef5eaab038c34a95a2 bugzilla: 182217 https://gitee.com/openeuler/kernel/issues/I4EFOS Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i... -------------------------------- 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> Signed-off-by: Chen Jun <chenjun102@huawei.com> Acked-by: Weilong Chen <chenweilong@huawei.com> Signed-off-by: Chen Jun <chenjun102@huawei.com> --- kernel/audit_tree.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/audit_tree.c b/kernel/audit_tree.c index 6c91902f4f45..39241207ec04 100644 --- a/kernel/audit_tree.c +++ b/kernel/audit_tree.c @@ -593,7 +593,6 @@ static void prune_tree_chunks(struct audit_tree *victim, bool tagged) spin_lock(&hash_lock); } spin_unlock(&hash_lock); - put_tree(victim); } /* @@ -602,6 +601,7 @@ static void prune_tree_chunks(struct audit_tree *victim, bool tagged) static void prune_one(struct audit_tree *victim) { prune_tree_chunks(victim, false); + put_tree(victim); } /* trim the uncommitted chunks from tree */ -- 2.20.1