我的 xinetd 守护进程在内核升级(从 2.6.24 到 2.6.33)后突然停止工作。我运行了一个 strace 并发现了这个:
[...]
close(3) = 0
munmap(0x7f1a93b43000, 4096) = 0
getrlimit(RLIMIT_NOFILE, {rlim_cur=8*1024, rlim_max=16*1024}) = 0
setrlimit(RLIMIT_NOFILE, {rlim_cur=1024, rlim_max=1024}) = 0
close(3) = 4294967287
exit_group(1) = ?
所以基本上,看起来关闭系统调用返回的东西不同于 0 或 -1
我做了几个测试,似乎它只发生在 64 位可执行文件中:
$ file closetest32
closetest32: ELF 32-bit LSB executable, Intel 80386, version 1 (SYSV), statically linked, not stripped
$ strace closetest32
execve("./closetest32", ["closetest32"], [/* 286 vars */]) = 0
[ Process PID=4731 runs in 32 bit mode. ]
open("/proc/mounts", O_RDONLY) = 3
close(3) = 0
close(3) = -1 EBADF (Bad file descriptor)
_exit(0) = ?
$ file closetest64
closetest64: ELF 64-bit LSB executable, AMD x86-64, version 1 (SYSV), statically linked, not stripped
$ strace closetest64
execve("./closetest64", ["closetest64"], [/* 286 vars */]) = 0
open("/proc/mounts", O_RDONLY) = 3
close(3) = 0
close(3) = 4294967287
_exit(0) = ?
我正在运行以下内核:
Linux foobar01 2.6.33.9-rt31.64.el5rt #1 SMP PREEMPT RT Wed May 4 10:34:12 EDT 2011 x86_64 x86_64 x86_64 GNU/Linux
最糟糕的是,我无法在另一台具有相同内核的机器上重现该错误。
有任何想法吗 ?
编辑:根据要求:这是用于 closetest32 和 closetest64 的代码
closetest32.asm:
.section .data
filename:
.ascii "/proc/mounts"
.section .text
.globl _start
_start:
xorl %edi, %edi
movl $5, %eax # open() i386 system call
leal filename, %ebx # %ebx ---> filename
movl $0, %esi # O_RDONLY flag into esi
int $0x80
xorl %edi, %edi
movl $6, %eax # close() i386 system call
movl $3, %ebx # fd 3
int $0x80
xorl %edi, %edi
movl $6, %eax # close() i386 system call
movl $3, %ebx # fd 3
int $0x80
## terminate program via _exit () system call
movl $1, %eax # %eax = _exit() i386 system call
xorl %ebx, %ebx # %ebx = 0 normal program return code
int $0x80
编译为:
as test32.asm -o test32.o --32
ld -m elf_i386 test32.o -o closetest32
closetest64.asm:
.section .data
filename:
.ascii "/proc/mounts"
.section .text
.globl _start
_start:
xorq %rdi, %rdi
movq $2, %rax # open() system call
leaq filename, %rdi # %rdi ---> filename
movq $0, %rsi # O_RDONLY flag into rsi
syscall
xorq %rdi, %rdi
movq $3, %rax # close() system call
movq $3, %rdi # fd 3
syscall
xorq %rdi, %rdi
movq $3, %rax # close() system call
movq $3, %rdi # fd 3
syscall
## terminate program via _exit () system call
movq $60, %rax # %rax = _exit() system call
xorq %rdi, %rdi # %rdi = 0 normal program return code
syscall
汇编:
as test64.asm -o test64.o
ld test64.o -o closetest64