Re: [Linux-kernel-mentees] [PATCH net] ethtool: strset: Fix out of bound read in strset_parse_request()

[Jakub Kicinski]

On Sun, 11 Oct 2020 02:39:29 +0530 Anmol Karn wrote:
> Flag ``ETHTOOL_A_STRSET_COUNTS_ONLY`` tells the kernel to only return the string 
> counts of the sets, but, when req_info->counts_only tries to read the 
> tb[ETHTOOL_A_STRSET_COUNTS_ONLY] it gets out of bound. 
> 
> - net/ethtool/strset.c
> The bug seems to trigger in this line:
> 
> req_info->counts_only = tb[ETHTOOL_A_STRSET_COUNTS_ONLY];
> 
> Fix it by NULL checking for req_info->counts_only while 
> reading from tb[ETHTOOL_A_STRSET_COUNTS_ONLY].
> 
> Reported-by: syzbot+9d1389df89299fa368dc@xxxxxxxxxxxxxxxxxxxxxxxxx 
> Link: https://syzkaller.appspot.com/bug?id=730deff8fe9954a5e317924d9acff98d9c64a770 
> Signed-off-by: Anmol Karn <anmol.karan123@xxxxxxxxx>

I think the correct fix for this was already applied to net-next as:

 commit db972e532518 ("ethtool: strset: allow ETHTOOL_A_STRSET_COUNTS_ONLY attr")