In the rtw_pci_init_rx_ring function the "if (len > TRX_BD_IDX_MASK)" statement guarantees that len is less than or equal to GENMASK(11, 0) or in other words that len is less than or equal to 4095. However the rx_ring->buf has a size of RTK_MAX_RX_DESC_NUM (defined as 512). This way it is possible an out-of-bounds write in the for statement due to the i variable can exceed the rx_ring->buff size.
Fix it using the ARRAY_SIZE macro.
Cc: stable@vger.kernel.org Addresses-Coverity-ID: 1461515 ("Out-of-bounds write") Fixes: e3037485c68ec ("rtw88: new Realtek 802.11ac driver") Signed-off-by: Len Baker len.baker@gmx.com --- drivers/net/wireless/realtek/rtw88/pci.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/net/wireless/realtek/rtw88/pci.c b/drivers/net/wireless/realtek/rtw88/pci.c index e7d17ab8f113..b9d8c049e776 100644 --- a/drivers/net/wireless/realtek/rtw88/pci.c +++ b/drivers/net/wireless/realtek/rtw88/pci.c @@ -280,7 +280,7 @@ static int rtw_pci_init_rx_ring(struct rtw_dev *rtwdev, } rx_ring->r.head = head;
- for (i = 0; i < len; i++) { + for (i = 0; i < ARRAY_SIZE(rx_ring->buf); i++) { skb = dev_alloc_skb(buf_sz); if (!skb) { allocated = i; -- 2.25.1
-----Original Message----- From: Len Baker [mailto:len.baker@gmx.com] Sent: Sunday, July 11, 2021 10:17 PM To: Yan-Hsuan Chuang; Kalle Valo; David S. Miller; Jakub Kicinski Cc: Len Baker; Stanislaw Gruszka; Brian Norris; linux-wireless@vger.kernel.org; netdev@vger.kernel.org; linux-kernel@vger.kernel.org; stable@vger.kernel.org Subject: [PATCH] rtw88: Fix out-of-bounds write
In the rtw_pci_init_rx_ring function the "if (len > TRX_BD_IDX_MASK)" statement guarantees that len is less than or equal to GENMASK(11, 0) or in other words that len is less than or equal to 4095. However the rx_ring->buf has a size of RTK_MAX_RX_DESC_NUM (defined as 512). This way it is possible an out-of-bounds write in the for statement due to the i variable can exceed the rx_ring->buff size.
Fix it using the ARRAY_SIZE macro.
Cc: stable@vger.kernel.org Addresses-Coverity-ID: 1461515 ("Out-of-bounds write") Fixes: e3037485c68ec ("rtw88: new Realtek 802.11ac driver") Signed-off-by: Len Baker len.baker@gmx.com
drivers/net/wireless/realtek/rtw88/pci.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/net/wireless/realtek/rtw88/pci.c b/drivers/net/wireless/realtek/rtw88/pci.c index e7d17ab8f113..b9d8c049e776 100644 --- a/drivers/net/wireless/realtek/rtw88/pci.c +++ b/drivers/net/wireless/realtek/rtw88/pci.c @@ -280,7 +280,7 @@ static int rtw_pci_init_rx_ring(struct rtw_dev *rtwdev,
I think "if (len > TRX_BD_IDX_MASK)" you mentioned is
if (len > TRX_BD_IDX_MASK) { rtw_err(rtwdev, "len %d exceeds maximum RX entries\n", len); return -EINVAL; }
This statement is used to ensure the length doesn't exceed hardware capability.
To prevent the 'len' argument from exceeding the array size of rx_ring->buff, I suggest to add another checking statement, like
if (len > ARRAY_SIZE(rx_ring->buf)) { rtw_err(rtwdev, "len %d exceeds maximum RX ring buffer\n", len); return -EINVAL; }
But, I wonder if this a false alarm because 'len' is equal to ARRAY_SIZE(rx_ring->buf) for now.
} rx_ring->r.head = head;
- for (i = 0; i < len; i++) {
- for (i = 0; i < ARRAY_SIZE(rx_ring->buf); i++) { skb = dev_alloc_skb(buf_sz); if (!skb) { allocated = i;
-- 2.25.1
-- Ping-Ke
On Sun, Jul 11, 2021 at 6:43 PM Pkshih pkshih@realtek.com wrote:
-----Original Message----- From: Len Baker [mailto:len.baker@gmx.com]
In the rtw_pci_init_rx_ring function the "if (len > TRX_BD_IDX_MASK)" statement guarantees that len is less than or equal to GENMASK(11, 0) or in other words that len is less than or equal to 4095. However the rx_ring->buf has a size of RTK_MAX_RX_DESC_NUM (defined as 512). This way it is possible an out-of-bounds write in the for statement due to the i variable can exceed the rx_ring->buff size.
Fix it using the ARRAY_SIZE macro.
Cc: stable@vger.kernel.org Addresses-Coverity-ID: 1461515 ("Out-of-bounds write")
Coverity seems to be giving a false warning here. I presume it's taking the |len| comparison as proof that |len| might be as large as TRX_BD_IDX_MASK, but as noted below, that's not really true; the |len| comparison is really just dead code.
Fixes: e3037485c68ec ("rtw88: new Realtek 802.11ac driver") Signed-off-by: Len Baker len.baker@gmx.com
To prevent the 'len' argument from exceeding the array size of rx_ring->buff, I suggest to add another checking statement, like
if (len > ARRAY_SIZE(rx_ring->buf)) { rtw_err(rtwdev, "len %d exceeds maximum RX ring buffer\n", len); return -EINVAL; }
That seems like a better idea, if we really need to patch anything.
But, I wonder if this a false alarm because 'len' is equal to ARRAY_SIZE(rx_ring->buf) for now.
Or to the point: rtw_pci_init_rx_ring() is only ever called with a fixed constant -- RTK_MAX_RX_DESC_NUM (i.e., 512) -- so the alleged overflow cannot happen.
Brian
On Mon, Jul 12, 2021 at 11:38:43AM -0700, Brian Norris wrote:
On Sun, Jul 11, 2021 at 6:43 PM Pkshih pkshih@realtek.com wrote:
-----Original Message----- From: Len Baker [mailto:len.baker@gmx.com]
In the rtw_pci_init_rx_ring function the "if (len > TRX_BD_IDX_MASK)" statement guarantees that len is less than or equal to GENMASK(11, 0) or in other words that len is less than or equal to 4095. However the rx_ring->buf has a size of RTK_MAX_RX_DESC_NUM (defined as 512). This way it is possible an out-of-bounds write in the for statement due to the i variable can exceed the rx_ring->buff size.
Fix it using the ARRAY_SIZE macro.
Cc: stable@vger.kernel.org Addresses-Coverity-ID: 1461515 ("Out-of-bounds write")
Coverity seems to be giving a false warning here. I presume it's taking the |len| comparison as proof that |len| might be as large as TRX_BD_IDX_MASK, but as noted below, that's not really true; the |len| comparison is really just dead code.
I agree.
Fixes: e3037485c68ec ("rtw88: new Realtek 802.11ac driver") Signed-off-by: Len Baker len.baker@gmx.com
To prevent the 'len' argument from exceeding the array size of rx_ring->buff, I suggest to add another checking statement, like
if (len > ARRAY_SIZE(rx_ring->buf)) { rtw_err(rtwdev, "len %d exceeds maximum RX ring buffer\n", len); return -EINVAL; }That seems like a better idea, if we really need to patch anything.
I think it is reasonable to protect any potencial overflow (for example, if this function is used in the future with a parameter greater than 512). It is better to be defensive in this case :)
But, I wonder if this a false alarm because 'len' is equal to ARRAY_SIZE(rx_ring->buf) for now.
Or to the point: rtw_pci_init_rx_ring() is only ever called with a fixed constant -- RTK_MAX_RX_DESC_NUM (i.e., 512) -- so the alleged overflow cannot happen.
Brian
I will send a v2 for review.
Thanks, Len
linux-stable-mirror@lists.linaro.org
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Brian Norris -
Len Baker -
Pkshih