[PATCH] net: ath10k: fix OOB: __ath10k_htt_rx_ring_fill_n

[PATCH] net: ath10k: fix OOB: __ath10k_htt_rx_ring_fill_n

[Zekun Shen]

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.

Signed-off-by: Zekun Shen <bruceshenzk@gmail.com>
---
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

 drivers/net/wireless/ath/ath10k/htt_rx.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/net/wireless/ath/ath10k/htt_rx.c b/drivers/net/wireless/ath/ath10k/htt_rx.c
index d787cbead..4e411b33a 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, "idx OOB, 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) {
-- 
2.17.1

Re: [PATCH] net: ath10k: fix OOB: __ath10k_htt_rx_ring_fill_n

[Kalle Valo]

Zekun Shen <bruceshenzk@gmail.com> writes:

> 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.
>
> Signed-off-by: Zekun Shen <bruceshenzk@gmail.com>
> ---
> 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

I added the log to the commit log as it looks useful.

Also I made minor changes to the title and to the error message.

-- 
https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches

Re: [PATCH] net: ath10k: fix OOB: __ath10k_htt_rx_ring_fill_n

[Kalle Valo]

Zekun Shen <bruceshenzk@gmail.com> wrote:

> 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@gmail.com>
> Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

Patch applied to ath-next branch of ath.git, thanks.

bad60b8d1a71 ath10k: check idx validity in __ath10k_htt_rx_ring_fill_n()

-- 
https://patchwork.kernel.org/patch/11621899/

https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches