[PATCH] ipw2x00: potential buffer overflow in libipw_wx_set_encodeext()

[PATCH] ipw2x00: potential buffer overflow in libipw_wx_set_encodeext()

[Dan Carpenter]

The "ext->key_len" is a u16 that comes from the user.  If it's over
SCM_KEY_LEN (32) that could lead to memory corruption.

Fixes: e0d369d1d969 ("[PATCH] ieee82011: Added WE-18 support to default wireless extension handler")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
---
 drivers/net/wireless/intel/ipw2x00/libipw_wx.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/net/wireless/intel/ipw2x00/libipw_wx.c b/drivers/net/wireless/intel/ipw2x00/libipw_wx.c
index a0cf78c418ac..27f15fa40528 100644
--- a/drivers/net/wireless/intel/ipw2x00/libipw_wx.c
+++ b/drivers/net/wireless/intel/ipw2x00/libipw_wx.c
@@ -633,8 +633,10 @@ int libipw_wx_set_encodeext(struct libipw_device *ieee,
 	}
 
 	if (ext->alg != IW_ENCODE_ALG_NONE) {
-		memcpy(sec.keys[idx], ext->key, ext->key_len);
-		sec.key_sizes[idx] = ext->key_len;
+		int len = min_t(int, ext->key_len, SCM_KEY_LEN);
+
+		memcpy(sec.keys[idx], ext->key, len);
+		sec.key_sizes[idx] = len;
 		sec.flags |= (1 << idx);
 		if (ext->alg == IW_ENCODE_ALG_WEP) {
 			sec.encode_alg[idx] = SEC_ALG_WEP;
-- 
2.30.1

Re: [PATCH] ipw2x00: potential buffer overflow in libipw_wx_set_encodeext()

[Stanislav Yakovlev]

On Tue, 2 Mar 2021 at 15:16, Dan Carpenter <dan.carpenter@oracle.com> wrote:
>
> The "ext->key_len" is a u16 that comes from the user.  If it's over
> SCM_KEY_LEN (32) that could lead to memory corruption.
>
> Fixes: e0d369d1d969 ("[PATCH] ieee82011: Added WE-18 support to default wireless extension handler")
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> ---
>  drivers/net/wireless/intel/ipw2x00/libipw_wx.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
>

Cc: stable@vger.kernel.org
Acked-by: Stanislav Yakovlev <stas.yakovlev@gmail.com>

Thanks, and sorry for the long review.

Stanislav.


> diff --git a/drivers/net/wireless/intel/ipw2x00/libipw_wx.c b/drivers/net/wireless/intel/ipw2x00/libipw_wx.c
> index a0cf78c418ac..27f15fa40528 100644
> --- a/drivers/net/wireless/intel/ipw2x00/libipw_wx.c
> +++ b/drivers/net/wireless/intel/ipw2x00/libipw_wx.c
> @@ -633,8 +633,10 @@ int libipw_wx_set_encodeext(struct libipw_device *ieee,
>         }
>
>         if (ext->alg != IW_ENCODE_ALG_NONE) {
> -               memcpy(sec.keys[idx], ext->key, ext->key_len);
> -               sec.key_sizes[idx] = ext->key_len;
> +               int len = min_t(int, ext->key_len, SCM_KEY_LEN);
> +
> +               memcpy(sec.keys[idx], ext->key, len);
> +               sec.key_sizes[idx] = len;
>                 sec.flags |= (1 << idx);
>                 if (ext->alg == IW_ENCODE_ALG_WEP) {
>                         sec.encode_alg[idx] = SEC_ALG_WEP;
> --
> 2.30.1
>

Re: [PATCH] ipw2x00: potential buffer overflow in libipw_wx_set_encodeext()

[Kalle Valo]

Stanislav Yakovlev <stas.yakovlev@gmail.com> writes:

> On Tue, 2 Mar 2021 at 15:16, Dan Carpenter <dan.carpenter@oracle.com> wrote:
>>
>> The "ext->key_len" is a u16 that comes from the user.  If it's over
>> SCM_KEY_LEN (32) that could lead to memory corruption.
>>
>> Fixes: e0d369d1d969 ("[PATCH] ieee82011: Added WE-18 support to
>> default wireless extension handler")
>> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
>> ---
>>  drivers/net/wireless/intel/ipw2x00/libipw_wx.c | 6 ++++--
>>  1 file changed, 4 insertions(+), 2 deletions(-)

[...]

>> --- a/drivers/net/wireless/intel/ipw2x00/libipw_wx.c
>> +++ b/drivers/net/wireless/intel/ipw2x00/libipw_wx.c
>> @@ -633,8 +633,10 @@ int libipw_wx_set_encodeext(struct libipw_device *ieee,
>>         }
>>
>>         if (ext->alg != IW_ENCODE_ALG_NONE) {
>> -               memcpy(sec.keys[idx], ext->key, ext->key_len);
>> -               sec.key_sizes[idx] = ext->key_len;
>> +               int len = min_t(int, ext->key_len, SCM_KEY_LEN);
>> +
>> +               memcpy(sec.keys[idx], ext->key, len);
>> +               sec.key_sizes[idx] = len;
>>                 sec.flags |= (1 << idx);
>>                 if (ext->alg == IW_ENCODE_ALG_WEP) {
>>                         sec.encode_alg[idx] = SEC_ALG_WEP;

In another thread Linus gave a good tip about clamp_val(), I think it
should be used it here as well to make the check safer and more
readable. And also elsewhere in wireless code with similar limits.

-- 
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