Re: [Dnsmasq-discuss] dnsmasqd crash
Hi Simon. The issue is reproducible on my device. It is very difficult for me to upgrade the current version to the latest. But after close investigation I found a bug in our code and the issue is resolved now. Basically domain in the 'forward_query' function should always point to the current server's domain. Thanks Justin From: Dnsmasq-discuss on behalf of Simon Kelley Sent: Monday, 26 June 2017 8:49 a.m. To: dnsmasq-discuss@lists.thekelleys.org.uk Subject: Re: [Dnsmasq-discuss] dnsmasqd crash Can you reproduce the crash? What triggers it? 2.55 is seven years old now, and predates our use of git, so it's pretty difficult to point to a fix, but I suspect that this bug is long gone. Finding how to reproduce it and showing that it doesn't happen with newer releases would be the best way. Cheers, Simon. On 20/06/17 22:44, Justin Jose wrote: > Hi Kevin, > > Thank you for the response. Here are my answers for your questions. > > Q. What version of dnsmasq? > > [Ans] The dnsmasq version I am using is 2.55. > > Q. hostname_isequal is used in quite a few places and should never be > passed a null pointer, so in my opinion the fix is a sticking plaster > over the issue and has the potential result of leaving null pointers > hanging around for other functions to fall over anyway. The root cause > should be found and squished. Any idea which particular call to > hostname_isequal was involved? > > [Ans:] When the crash happened, the call to hostname_isequal is occured from > forward_query at round line number 500. >I am not sure the reason for the NULL arguments here. > > Regards > Justin > > From: Dnsmasq-discuss on > behalf of Kevin Darbyshire-Bryant > Sent: Monday, 19 June 2017 8:56 p.m. > To: dnsmasq-discuss@lists.thekelleys.org.uk > Subject: Re: [Dnsmasq-discuss] dnsmasqd crash > > On 19/06/17 01:02, Justin Jose wrote: >> Hi, >> >> >> I got a couple of dnsmasqd crash and on investigating I found the crash >> is due to accessing a NULL pointer. > > What version of dnsmasq? > >> >> I have a fix for this problem and attached with this mail. >> >> >> Would you have any suggestion for this fix? > > hostname_isequal is used in quite a few places and should never be > passed a null pointer, so in my opinion the fix is a sticking plaster > over the issue and has the potential result of leaving null pointers > hanging around for other functions to fall over anyway. The root cause > should be found and squished. Any idea which particular call to > hostname_isequal was involved? > > Cheers, > > Kevin > > ___ > Dnsmasq-discuss mailing list > Dnsmasq-discuss@lists.thekelleys.org.uk > http://lists.thekelleys.org.uk/mailman/listinfo/dnsmasq-discuss > ___ > Dnsmasq-discuss mailing list > Dnsmasq-discuss@lists.thekelleys.org.uk > http://lists.thekelleys.org.uk/mailman/listinfo/dnsmasq-discuss > ___ Dnsmasq-discuss mailing list Dnsmasq-discuss@lists.thekelleys.org.uk http://lists.thekelleys.org.uk/mailman/listinfo/dnsmasq-discuss ___ Dnsmasq-discuss mailing list Dnsmasq-discuss@lists.thekelleys.org.uk http://lists.thekelleys.org.uk/mailman/listinfo/dnsmasq-discuss
Re: [Dnsmasq-discuss] dnsmasqd crash
Can you reproduce the crash? What triggers it? 2.55 is seven years old now, and predates our use of git, so it's pretty difficult to point to a fix, but I suspect that this bug is long gone. Finding how to reproduce it and showing that it doesn't happen with newer releases would be the best way. Cheers, Simon. On 20/06/17 22:44, Justin Jose wrote: > Hi Kevin, > > Thank you for the response. Here are my answers for your questions. > > Q. What version of dnsmasq? > > [Ans] The dnsmasq version I am using is 2.55. > > Q. hostname_isequal is used in quite a few places and should never be > passed a null pointer, so in my opinion the fix is a sticking plaster > over the issue and has the potential result of leaving null pointers > hanging around for other functions to fall over anyway. The root cause > should be found and squished. Any idea which particular call to > hostname_isequal was involved? > > [Ans:] When the crash happened, the call to hostname_isequal is occured from > forward_query at round line number 500. >I am not sure the reason for the NULL arguments here. > > Regards > Justin > > From: Dnsmasq-discuss on > behalf of Kevin Darbyshire-Bryant > Sent: Monday, 19 June 2017 8:56 p.m. > To: dnsmasq-discuss@lists.thekelleys.org.uk > Subject: Re: [Dnsmasq-discuss] dnsmasqd crash > > On 19/06/17 01:02, Justin Jose wrote: >> Hi, >> >> >> I got a couple of dnsmasqd crash and on investigating I found the crash >> is due to accessing a NULL pointer. > > What version of dnsmasq? > >> >> I have a fix for this problem and attached with this mail. >> >> >> Would you have any suggestion for this fix? > > hostname_isequal is used in quite a few places and should never be > passed a null pointer, so in my opinion the fix is a sticking plaster > over the issue and has the potential result of leaving null pointers > hanging around for other functions to fall over anyway. The root cause > should be found and squished. Any idea which particular call to > hostname_isequal was involved? > > Cheers, > > Kevin > > ___ > Dnsmasq-discuss mailing list > Dnsmasq-discuss@lists.thekelleys.org.uk > http://lists.thekelleys.org.uk/mailman/listinfo/dnsmasq-discuss > ___ > Dnsmasq-discuss mailing list > Dnsmasq-discuss@lists.thekelleys.org.uk > http://lists.thekelleys.org.uk/mailman/listinfo/dnsmasq-discuss > ___ Dnsmasq-discuss mailing list Dnsmasq-discuss@lists.thekelleys.org.uk http://lists.thekelleys.org.uk/mailman/listinfo/dnsmasq-discuss
Re: [Dnsmasq-discuss] dnsmasqd crash
Hi Kevin, Thank you for the response. Here are my answers for your questions. Q. What version of dnsmasq? [Ans] The dnsmasq version I am using is 2.55. Q. hostname_isequal is used in quite a few places and should never be passed a null pointer, so in my opinion the fix is a sticking plaster over the issue and has the potential result of leaving null pointers hanging around for other functions to fall over anyway. The root cause should be found and squished. Any idea which particular call to hostname_isequal was involved? [Ans:] When the crash happened, the call to hostname_isequal is occured from forward_query at round line number 500. I am not sure the reason for the NULL arguments here. Regards Justin From: Dnsmasq-discuss on behalf of Kevin Darbyshire-Bryant Sent: Monday, 19 June 2017 8:56 p.m. To: dnsmasq-discuss@lists.thekelleys.org.uk Subject: Re: [Dnsmasq-discuss] dnsmasqd crash On 19/06/17 01:02, Justin Jose wrote: > Hi, > > > I got a couple of dnsmasqd crash and on investigating I found the crash > is due to accessing a NULL pointer. What version of dnsmasq? > > I have a fix for this problem and attached with this mail. > > > Would you have any suggestion for this fix? hostname_isequal is used in quite a few places and should never be passed a null pointer, so in my opinion the fix is a sticking plaster over the issue and has the potential result of leaving null pointers hanging around for other functions to fall over anyway. The root cause should be found and squished. Any idea which particular call to hostname_isequal was involved? Cheers, Kevin ___ Dnsmasq-discuss mailing list Dnsmasq-discuss@lists.thekelleys.org.uk http://lists.thekelleys.org.uk/mailman/listinfo/dnsmasq-discuss ___ Dnsmasq-discuss mailing list Dnsmasq-discuss@lists.thekelleys.org.uk http://lists.thekelleys.org.uk/mailman/listinfo/dnsmasq-discuss
Re: [Dnsmasq-discuss] dnsmasqd crash
Probably best to reply to the list as well where there are much better experts than me. On 19/06/17 22:39, Justin Jose wrote: Hi Kevin, Thank you for the response. Here are my answers for your questions. Q. What version of dnsmasq? [Ans] The dnsmasq version I am using is 2.55. 2.55 is some 7 years old, 2.77 being released 2 weeks or so ago and 2.78 fixing a couple of oversights in that release due 'soon'. Q. hostname_isequal is used in quite a few places and should never be passed a null pointer, so in my opinion the fix is a sticking plaster over the issue and has the potential result of leaving null pointers hanging around for other functions to fall over anyway. The root cause should be found and squished. Any idea which particular call to hostname_isequal was involved? [Ans:] When the crash happened, the call to hostname_isequal is occured from forward_query at round line number 500. I am not sure the reason for the NULL arguments here. The first step here has to be to update to a much more recent version of dnsmasq and see if the problem still occurs. Is the error repeatable? If so, that would make testing a lot easier. Cheers, Kevin ___ Dnsmasq-discuss mailing list Dnsmasq-discuss@lists.thekelleys.org.uk http://lists.thekelleys.org.uk/mailman/listinfo/dnsmasq-discuss
Re: [Dnsmasq-discuss] dnsmasqd crash
On 19/06/17 01:02, Justin Jose wrote: Hi, I got a couple of dnsmasqd crash and on investigating I found the crash is due to accessing a NULL pointer. What version of dnsmasq? I have a fix for this problem and attached with this mail. Would you have any suggestion for this fix? hostname_isequal is used in quite a few places and should never be passed a null pointer, so in my opinion the fix is a sticking plaster over the issue and has the potential result of leaving null pointers hanging around for other functions to fall over anyway. The root cause should be found and squished. Any idea which particular call to hostname_isequal was involved? Cheers, Kevin ___ Dnsmasq-discuss mailing list Dnsmasq-discuss@lists.thekelleys.org.uk http://lists.thekelleys.org.uk/mailman/listinfo/dnsmasq-discuss
[Dnsmasq-discuss] dnsmasqd crash
???Hi,
I got a couple of dnsmasqd crash and on investigating I found the crash is due
to accessing a NULL pointer.
I have a fix for this problem and attached with this mail.
Would you have any suggestion for this fix?
Thanks
Justin
CR-57199: Fix dnsmasqd crash
From: Justin Jose
The crash is caused by accessing NULL pointer in hostname_isequal().
If any string is NULL return "not equal" without string comparison.
---
src/util.c |3 +++
1 file changed, 3 insertions(+)
diff --git a/src/util.c b/src/util.c
index 6b193b7..b41d814 100644
--- a/src/util.c
+++ b/src/util.c
@@ -286,6 +286,9 @@ int hostname_isequal(char *a, char *b)
{
unsigned int c1, c2;
+ if (a == NULL || b == NULL)
+return 0;
+
do {
c1 = (unsigned char) *a++;
c2 = (unsigned char) *b++;
___
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