[PATCH] ath11k: Fix a NULL pointer dereference in ath11k_mac_op_hw_scan()

[PATCH] ath11k: Fix a NULL pointer dereference in ath11k_mac_op_hw_scan()

[Zhou Qingyang]

In ath11k_mac_op_hw_scan(), the return value of kzalloc() is directly
used in memcpy(), which may lead to a NULL pointer dereference on
failure of kzalloc().

Fix this bug by adding a check of arg.extraie.ptr.

This bug was found by a static analyzer. The analysis employs
differential checking to identify inconsistent security operations
(e.g., checks or kfrees) between two code paths and confirms that the
inconsistent operations are not recovered in the current function or
the callers, so they constitute bugs.

Note that, as a bug found by static analysis, it can be a false
positive or hard to trigger. Multiple researchers have cross-reviewed
the bug.

Builds with CONFIG_ATH11K=m show no new warnings, and our static
analyzer no longer warns about this code.

Fixes: d5c65159f289 ("ath11k: driver for Qualcomm IEEE 802.11ax devices")
Signed-off-by: Zhou Qingyang <zhou1615@umn.edu>
---
 drivers/net/wireless/ath/ath11k/mac.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/net/wireless/ath/ath11k/mac.c b/drivers/net/wireless/ath/ath11k/mac.c
index 1cc55602787b..095f1f9b7611 100644
--- a/drivers/net/wireless/ath/ath11k/mac.c
+++ b/drivers/net/wireless/ath/ath11k/mac.c
@@ -3237,8 +3237,13 @@ static int ath11k_mac_op_hw_scan(struct ieee80211_hw *hw,
 	arg.scan_id = ATH11K_SCAN_ID;
 
 	if (req->ie_len) {
-		arg.extraie.len = req->ie_len;
 		arg.extraie.ptr = kzalloc(req->ie_len, GFP_KERNEL);
+		if (!arg.extraie.ptr) {
+			ret = -ENOMEM;
+			goto exit;
+		}
+
+		arg.extraie.len = req->ie_len;
 		memcpy(arg.extraie.ptr, req->ie, req->ie_len);
 	}
 
-- 
2.25.1

Re: [PATCH] ath11k: Fix a NULL pointer dereference in ath11k_mac_op_hw_scan()

[Jeff Johnson]

On 11/30/2021 12:43 AM, Zhou Qingyang wrote:
> In ath11k_mac_op_hw_scan(), the return value of kzalloc() is directly
> used in memcpy(), which may lead to a NULL pointer dereference on
> failure of kzalloc().
> 
> Fix this bug by adding a check of arg.extraie.ptr.
> 
> This bug was found by a static analyzer. The analysis employs
> differential checking to identify inconsistent security operations
> (e.g., checks or kfrees) between two code paths and confirms that the
> inconsistent operations are not recovered in the current function or
> the callers, so they constitute bugs.
> 
> Note that, as a bug found by static analysis, it can be a false
> positive or hard to trigger. Multiple researchers have cross-reviewed
> the bug.
> 
> Builds with CONFIG_ATH11K=m show no new warnings, and our static
> analyzer no longer warns about this code.
> 
> Fixes: d5c65159f289 ("ath11k: driver for Qualcomm IEEE 802.11ax devices")
> Signed-off-by: Zhou Qingyang <zhou1615@umn.edu>
> ---
>   drivers/net/wireless/ath/ath11k/mac.c | 7 ++++++-
>   1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/wireless/ath/ath11k/mac.c b/drivers/net/wireless/ath/ath11k/mac.c
> index 1cc55602787b..095f1f9b7611 100644
> --- a/drivers/net/wireless/ath/ath11k/mac.c
> +++ b/drivers/net/wireless/ath/ath11k/mac.c
> @@ -3237,8 +3237,13 @@ static int ath11k_mac_op_hw_scan(struct ieee80211_hw *hw,
>   	arg.scan_id = ATH11K_SCAN_ID;
>   
>   	if (req->ie_len) {
> -		arg.extraie.len = req->ie_len;
>   		arg.extraie.ptr = kzalloc(req->ie_len, GFP_KERNEL);

Your patch looks good, but since you are touching this code IMO this 
should be changed to kmemdup() and we should remove the memcpy() below.

> +		if (!arg.extraie.ptr) {
> +			ret = -ENOMEM;
> +			goto exit;
> +		}
> +
> +		arg.extraie.len = req->ie_len;
>   		memcpy(arg.extraie.ptr, req->ie, req->ie_len);
>   	}
>   
> 

[PATCH v2] ath11k: Fix a NULL pointer dereference in ath11k_mac_op_hw_scan()

[Zhou Qingyang]

In ath11k_mac_op_hw_scan(), the return value of kzalloc() is directly
used in memcpy(), which may lead to a NULL pointer dereference on
failure of kzalloc().

Fix this bug by adding a check of arg.extraie.ptr.

This bug was found by a static analyzer. The analysis employs
differential checking to identify inconsistent security operations
(e.g., checks or kfrees) between two code paths and confirms that the
inconsistent operations are not recovered in the current function or
the callers, so they constitute bugs.

Note that, as a bug found by static analysis, it can be a false
positive or hard to trigger. Multiple researchers have cross-reviewed
the bug.

Builds with CONFIG_ATH11K=m show no new warnings, and our static
analyzer no longer warns about this code.

Fixes: d5c65159f289 ("ath11k: driver for Qualcomm IEEE 802.11ax devices")
Signed-off-by: Zhou Qingyang <zhou1615@umn.edu>
---
Changes in v2:
  -  Use kmemdup() instead of kzalloc()

 drivers/net/wireless/ath/ath11k/mac.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/net/wireless/ath/ath11k/mac.c b/drivers/net/wireless/ath/ath11k/mac.c
index 1cc55602787b..dcefe444e7e3 100644
--- a/drivers/net/wireless/ath/ath11k/mac.c
+++ b/drivers/net/wireless/ath/ath11k/mac.c
@@ -3237,9 +3237,12 @@ static int ath11k_mac_op_hw_scan(struct ieee80211_hw *hw,
 	arg.scan_id = ATH11K_SCAN_ID;
 
 	if (req->ie_len) {
+		arg.extraie.ptr = kmemdup(req->ie, req->ie_len, GFP_KERNEL);
+		if (!arg.extraie.ptr) {
+			ret = -ENOMEM;
+			goto exit;
+		}
 		arg.extraie.len = req->ie_len;
-		arg.extraie.ptr = kzalloc(req->ie_len, GFP_KERNEL);
-		memcpy(arg.extraie.ptr, req->ie, req->ie_len);
 	}
 
 	if (req->n_ssids) {
-- 
2.25.1

Re: [PATCH v2] ath11k: Fix a NULL pointer dereference in ath11k_mac_op_hw_scan()

[Kalle Valo]

Zhou Qingyang <zhou1615@umn.edu> wrote:

> In ath11k_mac_op_hw_scan(), the return value of kzalloc() is directly
> used in memcpy(), which may lead to a NULL pointer dereference on
> failure of kzalloc().
> 
> Fix this bug by adding a check of arg.extraie.ptr.
> 
> This bug was found by a static analyzer. The analysis employs
> differential checking to identify inconsistent security operations
> (e.g., checks or kfrees) between two code paths and confirms that the
> inconsistent operations are not recovered in the current function or
> the callers, so they constitute bugs.
> 
> Note that, as a bug found by static analysis, it can be a false
> positive or hard to trigger. Multiple researchers have cross-reviewed
> the bug.
> 
> Builds with CONFIG_ATH11K=m show no new warnings, and our static
> analyzer no longer warns about this code.
> 
> Fixes: d5c65159f289 ("ath11k: driver for Qualcomm IEEE 802.11ax devices")
> Signed-off-by: Zhou Qingyang <zhou1615@umn.edu>
> Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com>

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

eccd25136386 ath11k: Fix a NULL pointer dereference in ath11k_mac_op_hw_scan()

-- 
https://patchwork.kernel.org/project/linux-wireless/patch/20211202155348.71315-1-zhou1615@umn.edu/

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