Calling rados_getxattrs() on a non-existent object causes segmentation faults

[matthi4s]

While messing around with rados_getxattrs() I got some strange "502 Bad gateway" errors, which were caused by segmentation faults in phprados. I don't really know anything about C and segmentation faults but after some searching and trying I discovered that it only occurs if the given object doesn't exist. It is possible to avoid this by checking with rados_stat() before if the object exists, but I think this should still be fixed and return an error array like the other functions.

Here is the output of my try to mess around with gdb:

GNU gdb (Ubuntu 7.11.1-0ubuntu1~16.5) 7.11.1
Copyright (C) 2016 Free Software Foundation, Inc.
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Reading symbols from /usr/sbin/php-fpm7.0...(no debugging symbols found)...done.
[New LWP 1880907]
[New LWP 1881270]
[New LWP 1881269]
[New LWP 1881268]
[New LWP 1881267]
[New LWP 1881265]
[New LWP 1881261]
[New LWP 1881260]
[New LWP 1881271]
[New LWP 1881263]
[New LWP 1881266]
[New LWP 1881264]
[New LWP 1881262]
[New LWP 1881272]
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".
Core was generated by `php-fpm: pool www                                                            '.
Program terminated with signal SIGABRT, Aborted.
#0  0x00007fb6fdd41428 in __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:54
54	../sysdeps/unix/sysv/linux/raise.c: No such file or directory.
[Current thread is 1 (Thread 0x7fb6ffc918c0 (LWP 1880907))]
(gdb) bt
#0  0x00007fb6fdd41428 in __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:54
#1  0x00007fb6fdd4302a in __GI_abort () at abort.c:89
#2  0x00007fb6fdd837ea in __libc_message (do_abort=do_abort@entry=2, fmt=fmt@entry=0x7fb6fde9ced8 "*** Error in `%s': %s: 0x%s ***\n") at ../sysdeps/posix/libc_fatal.c:175
#3  0x00007fb6fdd8c37a in malloc_printerr (ar_ptr=<optimized out>, ptr=<optimized out>, str=0x7fb6fde99caf "free(): invalid pointer", action=3) at malloc.c:5006
#4  _int_free (av=<optimized out>, p=<optimized out>, have_lock=0) at malloc.c:3867
#5  0x00007fb6fdd9053c in __GI___libc_free (mem=<optimized out>) at malloc.c:2968
#6  0x00007fb6ed64bc2d in librados::RadosXattrsIter::~RadosXattrsIter() () from /usr/lib/librados.so.2
#7  0x00007fb6ed607e94 in rados_getxattrs_end () from /usr/lib/librados.so.2
#8  0x00007fb6ed90dab0 in zif_rados_getxattrs (execute_data=<optimized out>, return_value=0x7fb6faa135c0) at /root/phprados/rados.c:1201
#9  0x0000560d5a6d40cd in ?? ()
#10 0x0000560d5a68f6cb in execute_ex ()
#11 0x0000560d5a6e3cf7 in zend_execute ()
#12 0x0000560d5a64ecb3 in zend_execute_scripts ()
#13 0x0000560d5a5edbb0 in php_execute_script ()
#14 0x0000560d5a4d1fe6 in main ()
(gdb) frame 8
#8  0x00007fb6ed90dab0 in zif_rados_getxattrs (execute_data=<optimized out>, return_value=0x7fb6faa135c0) at /root/phprados/rados.c:1201
1201	    rados_getxattrs_end(iter);
(gdb) info frame
Stack level 8, frame at 0x7ffe347a8fc0:
 rip = 0x7fb6ed90dab0 in zif_rados_getxattrs (/root/phprados/rados.c:1201); saved rip = 0x560d5a6d40cd
 called by frame at 0x7ffe347a9010, caller of frame at 0x7ffe347a8f50
 source language c.
 Arglist at 0x7ffe347a8f48, args: execute_data=<optimized out>, return_value=0x7fb6faa135c0
 Locals at 0x7ffe347a8f48, Previous frame's sp is 0x7ffe347a8fc0
 Saved registers:
  rbx at 0x7ffe347a8f90, rbp at 0x7ffe347a8f98, r12 at 0x7ffe347a8fa0, r13 at 0x7ffe347a8fa8, r14 at 0x7ffe347a8fb0, rip at 0x7ffe347a8fb8
(gdb) info args
execute_data = <optimized out>
return_value = 0x7fb6faa135c0
(gdb) info locals
ioctx_r = <optimized out>
oid = 0x7fb6faa67840
zioctx = 0x7fb6faa13650
iter = 0x560d5aa3f240 <executor_globals>
errDesc = 0x7fb6faa81840 "No such file or directory"
response = <optimized out>

I don't know if this is helpful at all or if you need the whole dump, let me know if you need any more information to solve this issue.