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 2471E3F7A9B; Mon, 17 Aug 2026 13:54:03 +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=1786974848; cv=none; b=lcnTeqOEYv+Z0/eQIDIUez2e0iYWkNikZiZu/bH4/Uk+asnSqcllf9y0t2T0kH0Z4nsUg9zJcdOEExdcB7nS9rmb2VSLobCmDcBEUfjyopYwuXCos0hu1ICKxbtUTEkiI4jNdgj6vwoxwLMIj1xq6oFpiFlABr0GNKWoGv62r8g= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786974848; c=relaxed/simple; bh=c0MpQfiAJeB1gvkL0Jrjqzg/KWOUpZ603yhzs23f2S4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=G3NBSIMtmqF5o7lbbjp2tXvBkMBhU1kmlwi3RGmgkxL3mXPn2pCUIYrv83yYApSOuXOmZmGnLQeUepWo1fUftpHAHtgtkhuf+jPzrrfMK65prSkscqHzaejP33xuly1fqvNYFST4xuGWlEaQjdEWBy4cJypf7fJ6O/ph0uLdWm8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=Yo33laLF; 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="Yo33laLF" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 50FDD1F000E9; Mon, 17 Aug 2026 13:54:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1786974841; bh=dj8VjlclRETNhdM4Li5KhgwCdgoTC2/KemczXW8eSTw=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=Yo33laLFlakKHw7K0rvzSwOY0VSinQ+g04M6e0YhyhT0ey3rWao43fIu1TZygyMqe /n1RBbbGav4V7Aa85eT9D5my9slu7WnOFxFETUsorDCX8n/mdLZiXRpydty+z0/+wv JyXbMEuq60SL27b2Y1L/RZ2YPi3YXAlLwq0yPe1U= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, AutonomousCodeSecurity@microsoft.com, "Xiang Mei (Microsoft)" , Nikolay Aleksandrov , Jay Vosburgh , Jakub Kicinski , Sasha Levin Subject: [PATCH 6.18 033/250] bonding: alb: re-check primary_is_promisc under RTNL in bond_alb_monitor Date: Mon, 17 Aug 2026 15:29:54 +0200 Message-ID: <20260817132537.806878457@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260817132536.466235697@linuxfoundation.org> References: <20260817132536.466235697@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 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Xiang Mei (Microsoft) [ Upstream commit 683c6ba6e58e6ed1037831ea97dd58d9c0e76b8d ] bond_alb_monitor() reads primary_is_promisc under RCU, then drops RCU and takes RTNL via rtnl_trylock() before undoing the promiscuity it set on the active slave. In that window the active slave can change under RTNL (RTM_DELLINK -> __bond_release_one() -> bond_alb_handle_active_change()), which already drops the promiscuity and clears primary_is_promisc. The monitor still acts on the stale decision: if the slave was removed with no failover, curr_active_slave is now NULL and the deref faults; if it failed over, the stale dev_set_promiscuity(-1) underflows the new slave's promiscuity counter and pins it in IFF_PROMISC. Oops: general protection fault, probably for non-canonical address ... KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007] Workqueue: b42 bond_alb_monitor RIP: 0010:bond_alb_monitor (drivers/net/bonding/bond_alb.c:1600) process_one_work (kernel/workqueue.c:3322) worker_thread (kernel/workqueue.c:3486) kthread (kernel/kthread.c:436) ret_from_fork (arch/x86/kernel/process.c:158) Kernel panic - not syncing: Fatal exception Re-check primary_is_promisc (and curr_active_slave) after taking RTNL so the monitor only undoes an increment it still owns. The other bonding monitors already re-read state under RTNL in their commit phase (bond_miimon_commit/bond_ab_arp_commit); bond_alb_monitor() was the only one acting on the pre-trylock decision. Fixes: d0e81b7e2246 ("bonding: Acquire correct locks in alb for promisc change") Reported-by: AutonomousCodeSecurity@microsoft.com Signed-off-by: Xiang Mei (Microsoft) Reviewed-by: Nikolay Aleksandrov Acked-by: Jay Vosburgh Link: https://patch.msgid.link/20260725233930.2957317-1-xmei5@asu.edu Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- drivers/net/bonding/bond_alb.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/drivers/net/bonding/bond_alb.c b/drivers/net/bonding/bond_alb.c index 2d37b07c8215c..839f7482dc182 100644 --- a/drivers/net/bonding/bond_alb.c +++ b/drivers/net/bonding/bond_alb.c @@ -1534,8 +1534,8 @@ void bond_alb_monitor(struct work_struct *work) struct bonding *bond = container_of(work, struct bonding, alb_work.work); struct alb_bond_info *bond_info = &(BOND_ALB_INFO(bond)); + struct slave *slave, *curr; struct list_head *iter; - struct slave *slave; if (!bond_has_slaves(bond)) { atomic_set(&bond_info->tx_rebalance_counter, 0); @@ -1597,9 +1597,11 @@ void bond_alb_monitor(struct work_struct *work) * because a slave was disabled then * it can now leave promiscuous mode. */ - dev_set_promiscuity(rtnl_dereference(bond->curr_active_slave)->dev, - -1); - bond_info->primary_is_promisc = 0; + curr = rtnl_dereference(bond->curr_active_slave); + if (bond_info->primary_is_promisc && curr) { + dev_set_promiscuity(curr->dev, -1); + bond_info->primary_is_promisc = 0; + } rtnl_unlock(); rcu_read_lock(); -- 2.53.0