Bug 1308204

Created attachment 1126670 [details]
build.log

Created attachment 1126672 [details]
root.log

Created attachment 1126673 [details]
state.log

This bug appears to have been reported against 'rawhide' during the Fedora 24 development cycle.
Changing version to '24'.

More information and reason for this action is here:
https://fedoraproject.org/wiki/Fedora_Program_Management/HouseKeeping/Fedora24#Rawhide_Rebase

This blocks gqrx from being rebuilt in F24.

The errors are:

/builddir/build/BUILD/uhd-release_003_008_002/host/utils/cdecode.c: In function 'int base64_decode_value(char)':
/builddir/build/BUILD/uhd-release_003_008_002/host/utils/cdecode.c:11:266: error: narrowing conversion of '-1' from 'int' to 'char' inside { } [-Wnarrowing]
     static const char decoding[] = {62,-1,-1,-1,63,52,53,54,55,56,57,58,59,60,61,-1,-1,-1,-2,-1,-1,-1,0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,-1,-1,-1,-1,-1,-1,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51};
                                                                                                                                                                                                                                                                          ^
/builddir/build/BUILD/uhd-release_003_008_002/host/utils/cdecode.c:11:266: error: narrowing conversion of '-1' from 'int' to 'char' inside { } [-Wnarrowing]
/builddir/build/BUILD/uhd-release_003_008_002/host/utils/cdecode.c:11:266: error: narrowing conversion of '-1' from 'int' to 'char' inside { } [-Wnarrowing]
/builddir/build/BUILD/uhd-release_003_008_002/host/utils/cdecode.c:11:266: error: narrowing conversion of '-1' from 'int' to 'char' inside { } [-Wnarrowing]
/builddir/build/BUILD/uhd-release_003_008_002/host/utils/cdecode.c:11:266: error: narrowing conversion of '-1' from 'int' to 'char' inside { } [-Wnarrowing]
/builddir/build/BUILD/uhd-release_003_008_002/host/utils/cdecode.c:11:266: error: narrowing conversion of '-1' from 'int' to 'char' inside { } [-Wnarrowing]
/builddir/build/BUILD/uhd-release_003_008_002/host/utils/cdecode.c:11:266: error: narrowing conversion of '-2' from 'int' to 'char' inside { } [-Wnarrowing]
/builddir/build/BUILD/uhd-release_003_008_002/host/utils/cdecode.c:11:266: error: narrowing conversion of '-1' from 'int' to 'char' inside { } [-Wnarrowing]
/builddir/build/BUILD/uhd-release_003_008_002/host/utils/cdecode.c:11:266: error: narrowing conversion of '-1' from 'int' to 'char' inside { } [-Wnarrowing]
/builddir/build/BUILD/uhd-release_003_008_002/host/utils/cdecode.c:11:266: error: narrowing conversion of '-1' from 'int' to 'char' inside { } [-Wnarrowing]
/builddir/build/BUILD/uhd-release_003_008_002/host/utils/cdecode.c:11:266: error: narrowing conversion of '-1' from 'int' to 'char' inside { } [-Wnarrowing]
/builddir/build/BUILD/uhd-release_003_008_002/host/utils/cdecode.c:11:266: error: narrowing conversion of '-1' from 'int' to 'char' inside { } [-Wnarrowing]
/builddir/build/BUILD/uhd-release_003_008_002/host/utils/cdecode.c:11:266: error: narrowing conversion of '-1' from 'int' to 'char' inside { } [-Wnarrowing]
/builddir/build/BUILD/uhd-release_003_008_002/host/utils/cdecode.c:11:266: error: narrowing conversion of '-1' from 'int' to 'char' inside { } [-Wnarrowing]
/builddir/build/BUILD/uhd-release_003_008_002/host/utils/cdecode.c:11:266: error: narrowing conversion of '-1' from 'int' to 'char' inside { } [-Wnarrowing]
/builddir/build/BUILD/uhd-release_003_008_002/host/utils/cdecode.c:11:266: error: narrowing conversion of '-1' from 'int' to 'char' inside { } [-Wnarrowing]

I was surprised that code ever worked on ARM, and in fact it looks like it doesn't:

https://sourceforge.net/p/libb64/bugs/1/

Also https://sourceforge.net/p/libb64/bugs/2/ deals with the same bug, but misses another one. I've attached an improved patch there.

I think it's clear to me how to fix it (IIRC I fixed this gcc speciality in few other packages), but I am too lazy to patch it :) I will probably rebase the uhd package as I have already done in rawhide.

Simply casting the literals to char won't fix it, the code is broken and doesn't work correctly (even on x86, see my comment at https://sourceforge.net/p/libb64/bugs/2/ about the off-by-one error).

Thanks for info, it seems upstream workaround it the following way [1]:

- they switched from c++ to c, because it's C code,  so the C++11 requirements doesn't apply
- they used explicit conversion the following way:

if ((signed char)value_in < 0 || value_in > decoding_size) return -1;

It seems to compile and work (maybe it relies on gcc behaviour - I am not good at C standards).

[1] https://github.com/EttusResearch/uhd/blob/master/host/lib/usrp/x300/cdecode.c

"It compiles" doesn't mean it's not still horribly broken.

For a start, as I've already said, that line you quoted has an off-by-one error. If value_in == decoding_size then it accesses off the end of the array.

Also, for signed char, if value_in is -128 then this subtraction:

 value_in -= 43;

at https://github.com/EttusResearch/uhd/blob/master/host/lib/usrp/x300/cdecode.c#L13 will underflow, with undefined behaviour.

And when char is unsigned this cast has implementation-defined behaviour (so it works with GCC, but could produce the wrong result and/or raise a signal with other compilers):

                } while ((signed char)fragment < 0);

The code stinks.

Right, it relies on undefined gcc behavior, but there is still off by one error. I will patch it downstream. Are you going to pull request your patch to uhd upstream?

Yes, will do.

Thanks.

Applying https://github.com/EttusResearch/uhd/pull/60 downstream.

uhd-3.9.4-2.fc24 gr-osmosdr-0.1.3-19.20141023git42c66fdd.fc24 gnuradio-3.7.9.1-4.fc24 has been submitted as an update to Fedora 24. https://bodhi.fedoraproject.org/updates/FEDORA-2016-22f4609f86

gnuradio-3.7.9.1-4.fc24, gr-osmosdr-0.1.3-19.20141023git42c66fdd.fc24, uhd-3.9.4-2.fc24 has been pushed to the Fedora 24 testing repository. If problems still persist, please make note of it in this bug report.
See https://fedoraproject.org/wiki/QA:Updates_Testing for
instructions on how to install test updates.
You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2016-22f4609f86

*** Bug 1352168 has been marked as a duplicate of this bug. ***

*** Bug 1352298 has been marked as a duplicate of this bug. ***

gnuradio-3.7.9.1-4.fc24, gr-osmosdr-0.1.3-19.20141023git42c66fdd.fc24, uhd-3.9.4-2.fc24 has been pushed to the Fedora 24 stable repository. If problems still persist, please make note of it in this bug report.