From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0C28D3B2FC0; Tue, 21 Jul 2026 20:33:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784666028; cv=none; b=Z81Or+AdgusSX08SHy/aVnlzuQRHfZV5CqZGGXNCtOY1s9q69Q0hefmOc0vXs5lVmajNYammgR0OEw7B9G0OfDnQSs41IoAAgL9DQ5oaYlqw+hIc4GyJ/qtm3Xu6ENoMcDbF7QYYXNNxRUZA+x32dB6IllSE//7SuySim9Xqp0A= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784666028; c=relaxed/simple; bh=rS44M745p3RIEA+6LDRyaiqhQkkS8y7Di83y0q/ZuS0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=p7x/GbIHSgeso5JfMPkocrOqPq0yafXfIZOeydOkvcDq+bs8SEfwL1JsJmjyfVq+bgo5rquMS93ZvhgFb4CufjhtlZnJltVhHyyP6TjqGZ/guHyQQgHMX0Uo6o6Fj57Po+fEHqO8oJz6RGuqOgtMir3IV7KKcOc/Xqo42HhpEXg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=i0rbF/6g; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="i0rbF/6g" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 741F51F000E9; Tue, 21 Jul 2026 20:33:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1784666026; bh=HuRFE4oTvmkH9wn7NNiQaXuegrTE9bZPNWUUnwChLu8=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=i0rbF/6gNEf3vZWGmFAg9m02NSAEx27aEipbOy2fyzh2c2IvjRPfGxgbKjNo0RlXN cZaEfqy9+ousEVTQhfD8fa/psvVcyuEY2RlODi7g2say59xseiVKMIGS74NbImcJ5d 81PbmKedpwExTOel3vDBgXMlb+szAQZdIqQAJ+GI= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Dan Carpenter , Boris Burkov , Qu Wenruo , Filipe Manana , David Sterba , Sasha Levin Subject: [PATCH 6.6 0527/1266] btrfs: fix invalid pointer dereference in __btrfs_run_delayed_refs() Date: Tue, 21 Jul 2026 17:16:04 +0200 Message-ID: <20260721152453.647504839@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260721152441.786066624@linuxfoundation.org> References: <20260721152441.786066624@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Filipe Manana [ Upstream commit 486f8298b6188ff11ef1f4be7f1d5d2e4d1b1fae ] In the beginning of the loop, we try to obtain a locked delayed ref head, if 'locked_ref' is currently NULL, by calling btrfs_select_ref_head(), which can return an error pointer. If the error pointer is -EAGAIN we do a continue and go back to the beginning of the loop, which will not try again to call btrfs_select_ref_head() since 'locked_ref' is no longer NULL but it's ERR_PTR(-EAGAIN), and then we do: spin_lock(&locked_ref->lock); against a ERR_PTR(-EAGAIN) value, generating an invalid pointer dereference. Fix this by ensuring that 'locked_ref' is set to NULL when btrfs_select_ref_head() returns ERR_PTR(-EAGAIN) and incrementing 'count' as well, to prevent infinite looping. We do this by doing a goto to the bottom of the loop that already sets 'locked_ref' to NULL and does a cond_resched(), with an increment to 'count' right before the goto. These measures were in place before the refactoring in commit 0110a4c43451 ("btrfs: refactor __btrfs_run_delayed_refs loop") but were unintentionally lost afterwards. Reported-by: Dan Carpenter Link: https://lore.kernel.org/linux-btrfs/ag8ARRwykv8bpJ87@stanley.mountain/ Fixes: 0110a4c43451 ("btrfs: refactor __btrfs_run_delayed_refs loop") Reviewed-by: Boris Burkov Reviewed-by: Qu Wenruo Signed-off-by: Filipe Manana Signed-off-by: David Sterba Signed-off-by: Sasha Levin --- fs/btrfs/extent-tree.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c index fbeb515e178f35..72d32a254cdb5c 100644 --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -2061,7 +2061,8 @@ static noinline int __btrfs_run_delayed_refs(struct btrfs_trans_handle *trans, locked_ref = btrfs_obtain_ref_head(trans); if (IS_ERR_OR_NULL(locked_ref)) { if (PTR_ERR(locked_ref) == -EAGAIN) { - continue; + count++; + goto again; } else { break; } @@ -2109,7 +2110,7 @@ static noinline int __btrfs_run_delayed_refs(struct btrfs_trans_handle *trans, * Either success case or btrfs_run_delayed_refs_for_head * returned -EAGAIN, meaning we need to select another head */ - +again: locked_ref = NULL; cond_resched(); } while ((nr != -1 && count < nr) || locked_ref); -- 2.53.0