From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 2D70F1ED38 for ; Tue, 25 Jul 2023 11:14:45 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id A3522C433C8; Tue, 25 Jul 2023 11:14:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1690283685; bh=V1OLvUreOIR/zhVV3Hl08vvP+XxgYnrpdzJUaaxi4u0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=mVvY/4fxFzlGJqICUwjk3p6LIw47pfv1i5hJHmehc+zvhHV8uIH6cD5J0gt+JudFA aTfAN4kuHtMNUzoCLvuTBp2WhuxM47Bt4CO/g7mqbn6phCi7TZz4amt2OJNTGuYmle 6pW6mj7Kku8ENegkRAlW6oJvV6hAMOVWy4MvihOE= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Pieter Jansen van Vuuren , Edward Cree , "David S. Miller" , Sasha Levin Subject: [PATCH 5.10 085/509] sfc: fix crash when reading stats while NIC is resetting Date: Tue, 25 Jul 2023 12:40:24 +0200 Message-ID: <20230725104557.605720656@linuxfoundation.org> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230725104553.588743331@linuxfoundation.org> References: <20230725104553.588743331@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Edward Cree [ Upstream commit d1b355438b8325a486f087e506d412c4e852f37b ] efx_net_stats() (.ndo_get_stats64) can be called during an ethtool selftest, during which time nic_data->mc_stats is NULL as the NIC has been fini'd. In this case do not attempt to fetch the latest stats from the hardware, else we will crash on a NULL dereference: BUG: kernel NULL pointer dereference, address: 0000000000000038 RIP efx_nic_update_stats abridged calltrace: efx_ef10_update_stats_pf efx_net_stats dev_get_stats dev_seq_printf_stats Skipping the read is safe, we will simply give out stale stats. To ensure that the free in efx_ef10_fini_nic() does not race against efx_ef10_update_stats_pf(), which could cause a TOCTTOU bug, take the efx->stats_lock in fini_nic (it is already held across update_stats). Fixes: d3142c193dca ("sfc: refactor EF10 stats handling") Reviewed-by: Pieter Jansen van Vuuren Signed-off-by: Edward Cree Signed-off-by: David S. Miller Signed-off-by: Sasha Levin --- drivers/net/ethernet/sfc/ef10.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) diff --git a/drivers/net/ethernet/sfc/ef10.c b/drivers/net/ethernet/sfc/ef10.c index 32654fe1f8b59..3f53b5ea78410 100644 --- a/drivers/net/ethernet/sfc/ef10.c +++ b/drivers/net/ethernet/sfc/ef10.c @@ -1297,8 +1297,10 @@ static void efx_ef10_fini_nic(struct efx_nic *efx) { struct efx_ef10_nic_data *nic_data = efx->nic_data; + spin_lock_bh(&efx->stats_lock); kfree(nic_data->mc_stats); nic_data->mc_stats = NULL; + spin_unlock_bh(&efx->stats_lock); } static int efx_ef10_init_nic(struct efx_nic *efx) @@ -1836,9 +1838,14 @@ static size_t efx_ef10_update_stats_pf(struct efx_nic *efx, u64 *full_stats, efx_ef10_get_stat_mask(efx, mask); - efx_nic_copy_stats(efx, nic_data->mc_stats); - efx_nic_update_stats(efx_ef10_stat_desc, EF10_STAT_COUNT, - mask, stats, nic_data->mc_stats, false); + /* If NIC was fini'd (probably resetting), then we can't read + * updated stats right now. + */ + if (nic_data->mc_stats) { + efx_nic_copy_stats(efx, nic_data->mc_stats); + efx_nic_update_stats(efx_ef10_stat_desc, EF10_STAT_COUNT, + mask, stats, nic_data->mc_stats, false); + } /* Update derived statistics */ efx_nic_fix_nodesc_drop_stat(efx, -- 2.39.2