This is a note to let you know that I've just added the patch titled ath10k: check idx validity in __ath10k_htt_rx_ring_fill_n() to the 5.8-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: ath10k-check-idx-validity-in-__ath10k_htt_rx_ring_fi.patch and it can be found in the queue-5.8 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 07b65053c6895ab873e6895df9240eac97d04c40 Author: Zekun Shen <bruceshenzk@xxxxxxxxx> Date: Tue Jun 23 18:11:05 2020 -0400 ath10k: check idx validity in __ath10k_htt_rx_ring_fill_n() [ Upstream commit bad60b8d1a7194df38fd7fe4b22f3f4dcf775099 ] The idx in __ath10k_htt_rx_ring_fill_n function lives in consistent dma region writable by the device. Malfunctional or malicious device could manipulate such idx to have a OOB write. Either by htt->rx_ring.netbufs_ring[idx] = skb; or by ath10k_htt_set_paddrs_ring(htt, paddr, idx); The idx can also be negative as it's signed, giving a large memory space to write to. It's possibly exploitable by corruptting a legit pointer with a skb pointer. And then fill skb with payload as rougue object. Part of the log here. Sometimes it appears as UAF when writing to a freed memory by chance. [ 15.594376] BUG: unable to handle page fault for address: ffff887f5c1804f0 [ 15.595483] #PF: supervisor write access in kernel mode [ 15.596250] #PF: error_code(0x0002) - not-present page [ 15.597013] PGD 0 P4D 0 [ 15.597395] Oops: 0002 [#1] SMP KASAN PTI [ 15.597967] CPU: 0 PID: 82 Comm: kworker/u2:2 Not tainted 5.6.0 #69 [ 15.598843] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.1-0-ga5cab58e9a3f-prebuilt.qemu.org 04/01/2014 [ 15.600438] Workqueue: ath10k_wq ath10k_core_register_work [ath10k_core] [ 15.601389] RIP: 0010:__ath10k_htt_rx_ring_fill_n (linux/drivers/net/wireless/ath/ath10k/htt_rx.c:173) ath10k_core Signed-off-by: Zekun Shen <bruceshenzk@xxxxxxxxx> Signed-off-by: Kalle Valo <kvalo@xxxxxxxxxxxxxx> Link: https://lore.kernel.org/r/20200623221105.3486-1-bruceshenzk@xxxxxxxxx Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/drivers/net/wireless/ath/ath10k/htt_rx.c b/drivers/net/wireless/ath/ath10k/htt_rx.c index d787cbead56ab..215ade6faf328 100644 --- a/drivers/net/wireless/ath/ath10k/htt_rx.c +++ b/drivers/net/wireless/ath/ath10k/htt_rx.c @@ -142,6 +142,14 @@ static int __ath10k_htt_rx_ring_fill_n(struct ath10k_htt *htt, int num) BUILD_BUG_ON(HTT_RX_RING_FILL_LEVEL >= HTT_RX_RING_SIZE / 2); idx = __le32_to_cpu(*htt->rx_ring.alloc_idx.vaddr); + + if (idx < 0 || idx >= htt->rx_ring.size) { + ath10k_err(htt->ar, "rx ring index is not valid, firmware malfunctioning?\n"); + idx &= htt->rx_ring.size_mask; + ret = -ENOMEM; + goto fail; + } + while (num > 0) { skb = dev_alloc_skb(HTT_RX_BUF_SIZE + HTT_RX_DESC_ALIGN); if (!skb) {