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| author |   Richard Guy Briggs <rgb@redhat.com> | 2021-08-23 22:04:09 -0400 |
|---|---|---|
| committer |   Paul Moore <paul@paul-moore.com> | 2021-08-24 18:52:36 -0400 |
| commit | 67d69e9d1a6c889d98951c1d74b19332ce0565af (patch) | |
| tree | 9dc62b09fe7c96ec05736b532959b26959d07b75 | |
| parent | audit: add header protection to kernel/audit.h (diff) | |
| download | linux-dev-67d69e9d1a6c889d98951c1d74b19332ce0565af.tar.xz linux-dev-67d69e9d1a6c889d98951c1d74b19332ce0565af.zip | |
audit: move put_tree() to avoid trim_trees refcount underflow and UAF
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>
| -rw-r--r-- | kernel/audit_tree.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/audit_tree.c b/kernel/audit_tree.c index b2be4e978ba3..2cd7b5694422 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 */ |