[Bug 8611] syscalls with 6 arguments broken on x86 32bit

[bugzilla at busybox.net]

https://bugs.busybox.net/show_bug.cgi?id=8611

--- Comment #1 from Ronald Wahl <ronald.wahl at raritan.com> ---
Created attachment 6291
  --> https://bugs.busybox.net/attachment.cgi?id=6291&action=edit
small test tool that helps to verify the fix

The example is incomplete as there might be more 6arg syscalls like fallocate
that I havn't in this example. The file can be compiled with gcc on a 32bit x86
platform.

gcc -o syscall6-test syscall6-test.c

Prerequirement:

kernel 4.3+
uClibc build against kernel headers of linux 4.3+
strace 4.11+ (not sure if rebuild against linux 4.3 is necessary)

The interesting value is not the return value but the 6th parameter of the last
parameter of the syscalls below which is not as specified in the fail case
except for sync_file_range.

Fail case:
$ strace -e splice,sync_file_range,sendto,recvfrom syscall6_test 
splice(10, NULL, 11, NULL, 0, 0)        = 0
sync_file_range(10, 0, 0,
SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WAIT_AFTER) = -1 EBADF (Bad file
descriptor)
sendto(4,
"\250\0\0\0\374_y\267xX\256\277(Uy\2674X\256\277\0\20y\267\0\0\0\0\0\20y\267"...,
1024, 0, 0xbfae5780, 0) = -1 EINVAL (Invalid argument)
sendto() failed
+++ exited with 0 +++

Working case:
$ strace -e splice,sync_file_range,sendto,recvfrom syscall6_test 
splice(10, NULL, 11, NULL, 0,
SPLICE_F_MOVE|SPLICE_F_NONBLOCK|SPLICE_F_MORE|SPLICE_F_GIFT) = 0
sync_file_range(10, 0, 0,
SYNC_FILE_RANGE_WAIT_BEFORE|SYNC_FILE_RANGE_WAIT_AFTER) = -1 EBADF (Bad file
descriptor)
sendto(4,
"\250\0\0\0\374\237p\267\330\224\223\277(\225p\267\224\224\223\277\0Pp\267\0\0\0\0\0Pp\267"...,
1024, 0, {sa_family=AF_INET, sin_port=htons(46279),
sin_addr=inet_addr("127.0.0.1")}, 16) = 1024
recvfrom(3,
"\250\0\0\0\374\237p\267\330\224\223\277(\225p\267\224\224\223\277\0Pp\267\0\0\0\0\0Pp\267"...,
1024, 0, {sa_family=AF_INET, sin_port=htons(40050),
sin_addr=inet_addr("127.0.0.1")}, [16]) = 1024

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