* [PATCH] mac80211: Fix the buffer length in debugfs for smps @ 2014-01-04 21:06 Chaitanya T K 2014-01-06 14:48 ` Johannes Berg 0 siblings, 1 reply; 7+ messages in thread From: Chaitanya T K @ 2014-01-04 21:06 UTC (permalink / raw) To: johannes, linux-wireless; +Cc: Chaitanya T K This was blocking sending SMPS action frames through debugfs. Signed-off-by: Chaitanya T K <chaitanya.mgit@gmail.com> --- net/mac80211/debugfs_netdev.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/mac80211/debugfs_netdev.c b/net/mac80211/debugfs_netdev.c index 04b5a14..1a8fa5f 100644 --- a/net/mac80211/debugfs_netdev.c +++ b/net/mac80211/debugfs_netdev.c @@ -265,7 +265,7 @@ static ssize_t ieee80211_if_parse_smps(struct ieee80211_sub_if_data *sdata, enum ieee80211_smps_mode mode; for (mode = 0; mode < IEEE80211_SMPS_NUM_MODES; mode++) { - if (strncmp(buf, smps_modes[mode], buflen) == 0) { + if (strncmp(buf, smps_modes[mode], buflen-1) == 0) { int err = ieee80211_set_smps(sdata, mode); if (!err) return buflen; ^ permalink raw reply related [flat|nested] 7+ messages in thread
* Re: [PATCH] mac80211: Fix the buffer length in debugfs for smps 2014-01-04 21:06 [PATCH] mac80211: Fix the buffer length in debugfs for smps Chaitanya T K @ 2014-01-06 14:48 ` Johannes Berg 2014-01-06 15:05 ` Krishna Chaitanya 0 siblings, 1 reply; 7+ messages in thread From: Johannes Berg @ 2014-01-06 14:48 UTC (permalink / raw) To: Chaitanya T K; +Cc: linux-wireless On Sun, 2014-01-05 at 02:36 +0530, Chaitanya T K wrote: > This was blocking sending SMPS action frames > through debugfs. I don't see any issue here, explain. johannes ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] mac80211: Fix the buffer length in debugfs for smps 2014-01-06 14:48 ` Johannes Berg @ 2014-01-06 15:05 ` Krishna Chaitanya 2014-01-06 15:15 ` Johannes Berg 0 siblings, 1 reply; 7+ messages in thread From: Krishna Chaitanya @ 2014-01-06 15:05 UTC (permalink / raw) To: Johannes Berg; +Cc: linux-wireless On Mon, Jan 6, 2014 at 8:18 PM, Johannes Berg <johannes@sipsolutions.net> wrote: > On Sun, 2014-01-05 at 02:36 +0530, Chaitanya T K wrote: >> This was blocking sending SMPS action frames >> through debugfs. > > I don't see any issue here, explain. > > johannes > buflen includes the new line character as well, hence the comparison strncmp fails for all combiantions. echo "static" > ieee80211/phyX/netdev\:wlanX/smps Then buf=static\n buflen=7 But the comparison is with "static" which doesn't include "\n" hence the comparison fails. ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] mac80211: Fix the buffer length in debugfs for smps 2014-01-06 15:05 ` Krishna Chaitanya @ 2014-01-06 15:15 ` Johannes Berg 2014-01-06 15:32 ` Krishna Chaitanya 0 siblings, 1 reply; 7+ messages in thread From: Johannes Berg @ 2014-01-06 15:15 UTC (permalink / raw) To: Krishna Chaitanya; +Cc: linux-wireless On Mon, 2014-01-06 at 20:35 +0530, Krishna Chaitanya wrote: > On Mon, Jan 6, 2014 at 8:18 PM, Johannes Berg <johannes@sipsolutions.net> wrote: > > On Sun, 2014-01-05 at 02:36 +0530, Chaitanya T K wrote: > >> This was blocking sending SMPS action frames > >> through debugfs. > > > > I don't see any issue here, explain. > > > > johannes > > > buflen includes the new line character as well, hence the comparison > strncmp fails for all combiantions. > > echo "static" > ieee80211/phyX/netdev\:wlanX/smps > Then > > buf=static\n > buflen=7 > > But the comparison is with "static" which doesn't include "\n" > hence the comparison fails. Err, ok, so you can just do "echo -n static", right? And then your patch breaks the way it currently works, which is about the worst you can do. johannes ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] mac80211: Fix the buffer length in debugfs for smps 2014-01-06 15:15 ` Johannes Berg @ 2014-01-06 15:32 ` Krishna Chaitanya 2014-01-06 15:55 ` Johannes Berg 0 siblings, 1 reply; 7+ messages in thread From: Krishna Chaitanya @ 2014-01-06 15:32 UTC (permalink / raw) To: Johannes Berg; +Cc: linux-wireless On Mon, Jan 6, 2014 at 8:45 PM, Johannes Berg <johannes@sipsolutions.net> wrote: > On Mon, 2014-01-06 at 20:35 +0530, Krishna Chaitanya wrote: >> On Mon, Jan 6, 2014 at 8:18 PM, Johannes Berg <johannes@sipsolutions.net> wrote: >> > On Sun, 2014-01-05 at 02:36 +0530, Chaitanya T K wrote: >> >> This was blocking sending SMPS action frames >> >> through debugfs. >> > >> > I don't see any issue here, explain. >> > >> > johannes >> > >> buflen includes the new line character as well, hence the comparison >> strncmp fails for all combiantions. >> >> echo "static" > ieee80211/phyX/netdev\:wlanX/smps >> Then >> >> buf=static\n >> buflen=7 >> >> But the comparison is with "static" which doesn't include "\n" >> hence the comparison fails. > > Err, ok, so you can just do "echo -n static", right? > > And then your patch breaks the way it currently works, which is about > the worst you can do. > Ok, if one works other fails. So instead why cant we use strlen(local_string) instead of using buflen(remote). That way we can make sure we only compare the characters we need and leave out the extra ones. ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] mac80211: Fix the buffer length in debugfs for smps 2014-01-06 15:32 ` Krishna Chaitanya @ 2014-01-06 15:55 ` Johannes Berg 2014-01-06 16:46 ` Krishna Chaitanya 0 siblings, 1 reply; 7+ messages in thread From: Johannes Berg @ 2014-01-06 15:55 UTC (permalink / raw) To: Krishna Chaitanya; +Cc: linux-wireless On Mon, 2014-01-06 at 21:02 +0530, Krishna Chaitanya wrote: > On Mon, Jan 6, 2014 at 8:45 PM, Johannes Berg <johannes@sipsolutions.net> wrote: > > On Mon, 2014-01-06 at 20:35 +0530, Krishna Chaitanya wrote: > >> On Mon, Jan 6, 2014 at 8:18 PM, Johannes Berg <johannes@sipsolutions.net> wrote: > >> > On Sun, 2014-01-05 at 02:36 +0530, Chaitanya T K wrote: > >> >> This was blocking sending SMPS action frames > >> >> through debugfs. > >> > > >> > I don't see any issue here, explain. > >> > > >> > johannes > >> > > >> buflen includes the new line character as well, hence the comparison > >> strncmp fails for all combiantions. > >> > >> echo "static" > ieee80211/phyX/netdev\:wlanX/smps > >> Then > >> > >> buf=static\n > >> buflen=7 > >> > >> But the comparison is with "static" which doesn't include "\n" > >> hence the comparison fails. > > > > Err, ok, so you can just do "echo -n static", right? > > > > And then your patch breaks the way it currently works, which is about > > the worst you can do. > > > Ok, if one works other fails. > > So instead why cant we use strlen(local_string) > instead of using buflen(remote). That way we can make sure we only > compare the characters we need and leave out the extra ones. It wouldn't fix the problem and would introduce a buffer overflow bug. johannes ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] mac80211: Fix the buffer length in debugfs for smps 2014-01-06 15:55 ` Johannes Berg @ 2014-01-06 16:46 ` Krishna Chaitanya 0 siblings, 0 replies; 7+ messages in thread From: Krishna Chaitanya @ 2014-01-06 16:46 UTC (permalink / raw) To: Johannes Berg; +Cc: linux-wireless On Mon, Jan 6, 2014 at 9:25 PM, Johannes Berg <johannes@sipsolutions.net> wrote: > On Mon, 2014-01-06 at 21:02 +0530, Krishna Chaitanya wrote: >> On Mon, Jan 6, 2014 at 8:45 PM, Johannes Berg <johannes@sipsolutions.net> wrote: >> > On Mon, 2014-01-06 at 20:35 +0530, Krishna Chaitanya wrote: >> >> On Mon, Jan 6, 2014 at 8:18 PM, Johannes Berg <johannes@sipsolutions.net> wrote: >> >> > On Sun, 2014-01-05 at 02:36 +0530, Chaitanya T K wrote: >> >> >> This was blocking sending SMPS action frames >> >> >> through debugfs. >> >> > >> >> > I don't see any issue here, explain. >> >> > >> >> > johannes >> >> > >> >> buflen includes the new line character as well, hence the comparison >> >> strncmp fails for all combiantions. >> >> >> >> echo "static" > ieee80211/phyX/netdev\:wlanX/smps >> >> Then >> >> >> >> buf=static\n >> >> buflen=7 >> >> >> >> But the comparison is with "static" which doesn't include "\n" >> >> hence the comparison fails. >> > >> > Err, ok, so you can just do "echo -n static", right? >> > >> > And then your patch breaks the way it currently works, which is about >> > the worst you can do. >> > >> Ok, if one works other fails. >> >> So instead why cant we use strlen(local_string) >> instead of using buflen(remote). That way we can make sure we only >> compare the characters we need and leave out the extra ones. > > It wouldn't fix the problem and would introduce a buffer overflow bug. > We can add some checks to make sure it doesn't overflow, but its not worth it. My intention is as most of the users are familiar with "echo" and not "echo -n", its better to have a solution which works with "echo". Also if we use buflen-1 and give "echo -n" it still works but problem is it compares 1 less character. Anyways either one is fine with me. Thanks. ^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2014-01-06 16:47 UTC | newest] Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2014-01-04 21:06 [PATCH] mac80211: Fix the buffer length in debugfs for smps Chaitanya T K 2014-01-06 14:48 ` Johannes Berg 2014-01-06 15:05 ` Krishna Chaitanya 2014-01-06 15:15 ` Johannes Berg 2014-01-06 15:32 ` Krishna Chaitanya 2014-01-06 15:55 ` Johannes Berg 2014-01-06 16:46 ` Krishna Chaitanya
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