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 81AF2408039; Tue, 21 Jul 2026 19:27:04 +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=1784662025; cv=none; b=mufiqelhSSpFuxUWIy7DPEDvKVvdvA2NwHaTgIONYA5DtN8c9q2vN3AyZ6505GlYsU4dNYoGkQwM7DUIip/NWL5cjFvGAmcjjs3W4bY0egC14aaROgNvnKNLlSdK5DtaZRnFhaCMRVk2kTe5KJCNlWYTvL+xH//d0TkJLSf+kVs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784662025; c=relaxed/simple; bh=759uH0RC8XzRAjqXJlALaQ86n3ogPyOEB1nk0ekK1So=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=uH5modYvPe9fVy4ZrrvQ1/jAwwaTK/DhvsVEXxPTW/3yUsXccEwcmwPs8YhPLSxC1bSsUgw+cH6tLYE4M0Y5QTIzRaBVhcFyJ+ZwZ6LvFjV/SBVrdXhvn2vVzdvgKFHxsY7K4aFx+v/J1AgyOiDW6h3bXvfF3qc7EXsvrgXA4qc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=vnFko6b5; 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="vnFko6b5" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E58A61F000E9; Tue, 21 Jul 2026 19:27:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1784662024; bh=8qZl77h90GM1v7nUrhvkSY+y8jL09/LG0zJj8RcKitM=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=vnFko6b5HRywa7qaSP/DJSjBL873iiX9z/9yOReSf5xejmgCaRvfzPzI1TONmLOg8 wjIg3RcRA8uipdJMv6WdWaAkvniCEUK2mrXenhz7n8QihoXZzY/ZHl3Ss8GjMZVggF YYNJsnPaxzL5f9jOq6cVJMvfxmVKkKUgsLwAD9xU= 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 6.12 0289/1276] btrfs: fix invalid pointer dereference in __btrfs_run_delayed_refs() Date: Tue, 21 Jul 2026 17:12:12 +0200 Message-ID: <20260721152452.550387791@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260721152446.065700225@linuxfoundation.org> References: <20260721152446.065700225@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-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 e2defa21b6c7af..28dca13fb9b099 100644 --- a/fs/btrfs/extent-tree.c +++ b/fs/btrfs/extent-tree.c @@ -2075,7 +2075,8 @@ 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; } @@ -2123,7 +2124,7 @@ 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 ((min_bytes != U64_MAX && bytes_processed < min_bytes) || -- 2.53.0