busybox

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As discovered in https://github.com/docker-library/busybox/pull/202, busybox segfaults when running on real riscv64 hardware but works fine on QEMU 😭. Just opening this as a tracking issue.

+ gdb -core=rootfs/core -silent -ex bt full -ex quit busybox_unstripped
Reading symbols from busybox_unstripped...

warning: core file may not match specified executable file.
[New LWP 11]
Core was generated by `nslookup google.com'.
Program terminated with signal SIGSEGV, Segmentation fault.
#0  __GI_memset (dstpp=dstpp@entry=0x3ffc0d1530, c=c@entry=0, 
    len=<optimized out>, len@entry=16777216)
    at libc/string/generic/memset.c:50
50		  ((op_t *) dstp)[0] = cccc;
#0  __GI_memset (dstpp=dstpp@entry=0x3ffc0d1530, c=c@entry=0, 
    len=<optimized out>, len@entry=16777216)
    at libc/string/generic/memset.c:50
        xlen = <optimized out>
        cccc = 0
        dstp = 274811655472
#1  0x000000000010c220 in __poll_nocancel (fds=fds@entry=0x3ffd0d1628, 
    nfds=nfds@entry=1, timeout=<optimized out>)
    at libc/sysdeps/linux/common/poll.c:70
        max_fd_size = 1073741816
        tv = {tv_sec = 16, tv_usec = 2}
        rset = 0x3ffc0d1530
        wset = 0x3ffb0d1530
        xset = <optimized out>
        f = <optimized out>
        ready = <optimized out>
        error_num = <optimized out>
        maxfd = 0
        bytes = 16777216
#2  0x000000000010c740 in __GI_poll (fds=fds@entry=0x3ffd0d1628, 
    nfds=nfds@entry=1, timeout=timeout@entry=2500)
    at libc/sysdeps/linux/common/poll.c:215
        oldtype = <optimized out>
        result = <optimized out>
#3  0x0000000000047d68 in send_queries (ns=0x19e80e70)
    at networking/nslookup.c:569
        qn = <optimized out>
        recvlen = <optimized out>
        reply = "X\004\023\000\000\000\000\000h\004\023\000\000\000\000\000X\004\023\000\000\000\000\000\374\375\347\031", '\000' <repeats 12 times>, "\001", '\000' <repeats 15 times>, "\001", '\000' <repeats 16 times>, "\027\r\375?\000\000\000`r\027\000\000\000\000\000\024\235\022", '\000' <repeats 13 times>, "t\004\023\000\000\000\000\000X\004\023\000\000\000\000\000h\004\023\000\000\000\000\000X\004\023\000\000\000\000\000\374\375\347\031", '\000' <repeats 28 times>, "\001", '\000' <repeats 16 times>, "\027\r\375?\000\000\000`r\027\000\000\000\000\000"...
        rcode = <optimized out>
        local_lsa = 0x19e80850
        pfd = {fd = 3, events = 1, revents = 0}
        servfail_retry = 4
        n_replies = 0
        retry_interval = <optimized out>
        timeout = 5000
        tstart = 97021078
        tsent = 97021078
        tcur = 97021078
#4  0x00000000000484fc in nslookup_main (argc=<optimized out>, 
    argv=<optimized out>, argv@entry=0x3ffd0d1c98)
    at networking/nslookup.c:984
        c = <optimized out>
        types = 0
        rc = 0
        err = <optimized out>
#5  0x0000000000010b58 in run_applet_no_and_exit (applet_no=<optimized out>, 
    name=name@entry=0x3ffd0d1ed1 "nslookup", argv=argv@entry=0x3ffd0d1c98)
    at libbb/appletlib.c:969
        argc = <optimized out>
#6  0x0000000000010f28 in run_applet_and_exit (name=0x3ffd0d1ed1 "nslookup", 
    argv=argv@entry=0x3ffd0d1c98) at libbb/appletlib.c:988
        applet = <optimized out>
#7  0x0000000000010fc0 in main (argc=<optimized out>, argv=0x3ffd0d1c98)
    at libbb/appletlib.c:1128
No locals.

Originally posted by @tianon in https://github.com/docker-library/busybox/issues/202#issuecomment-2163880467