[PATCH] iw: Null check before accessing n_mcs variable

[PATCH] iw: Null check before accessing n_mcs variable

[Amit Khatri]

From: Amit Khatri <amit.khatri@samsung.com>
Date: Thu, 24 Aug 2017 00:16:26 -0700
Subject: [PATCH] iw: Null check before accessing n_mcs variable

If all cases will fail n_mcs variable fail to get any assignement
and remain NULL. so better to check NULL before dereference.
Signed-off-by: Amit Khatri <amit.khatri@samsung.com>
---
 bitrate.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/bitrate.c b/bitrate.c
index 4a026a4..3e58337 100644
--- a/bitrate.c
+++ b/bitrate.c
@@ -185,7 +185,8 @@ static int handle_bitrates(struct nl80211_state *state,
 				return 1;
 			if (tmpl < 0 || tmpl > 255)
 				return 1;
-			mcs[(*n_mcs)++] = tmpl;
+			if(n_mcs!=NULL)
+				mcs[(*n_mcs)++] = tmpl;
 			break;
 		case S_VHT:
 			if (*vht_argc >= VHT_ARGC_MAX)
-- 
1.7.9.5

Re: [PATCH] iw: Null check before accessing n_mcs variable

[Johannes Berg]

On Fri, 2017-09-01 at 06:10 +0000, Amit Khatri wrote:
> From: Amit Khatri <amit.khatri@samsung.com>
> Date: Thu, 24 Aug 2017 00:16:26 -0700
> Subject: [PATCH] iw: Null check before accessing n_mcs variable
> 
> If all cases will fail n_mcs variable fail to get any assignement
> and remain NULL. so better to check NULL before dereference.
> 

This is wrong - you can't get into S_HT state unless n_mcs was also
assigned, and if you can't get into S_HT state then you can't
dereference n_mcs either.

johannes