Re: shm_open failed:Invalid argument in glibc 2.20

[Cui Bixuan <cuibixuan at huawei dot com>]

On 2016/2/18 20:56, Adhemerval Zanella wrote:
> Hi
> 
> On 18-02-2016 00:29, Cui Bixuan wrote:
>> Hi,
>>     I have a testcase:
>>
>> test.c
>> #include <stdio.h>
>> #include <stdlib.h>
>> #include <unistd.h>
>> #include <string.h>
>> #include <signal.h>
>> #include <sys/types.h>
>> #include <errno.h>
>> #include <fcntl.h>
>> #include <stdint.h>
>> #include <sys/stat.h>
>> #include <sys/mman.h>
>> #include <sys/wait.h>
>>
>> //number of child progress
>> #define N 20
>> #define FILE_SIZE 4096
>>
>>
>> int main(int ac, char **av)
>> {
>>         pid_t pid;
>>         int state;
>>         int i, j;
>>         int ret = -1;
>>         int fd = -1;
>>         int FLAG = 0;
>>         unsigned char* add_fw = NULL;
>>         unsigned char* add_fr = NULL;
>>
>>         fd = shm_open("./a", O_RDWR|O_CREAT, 00700);
>>         if(-1 == (ret = fd))
>>         {
>>                 perror("shm_open fail\n");
>>                 printf("errno=%d, EINVAL:%d\n", errno, EINVAL);
>>                 FLAG++;
>>                 exit(FLAG);
>>         }
>>
>>         return(FLAG);
>> }
>>
>> It just test shm_open() syscall. And It failed in Arm64eb:
>>
>> linux /tmp # ./test_be
>> shm_open fail
>> : Invalid argument
>> errno=22, EINVAL:22
>>
>> (And shm_open("a", O_RDWR|O_CREAT, 00700) will pass I find;)
>>
>>
>> But it can pass in Arm64el:
>> ./test
>> echo $?
>> 0
>>
>> Then I compile it by:
>> aarch64-linux-gnu-gcc test.c -o test -static -lrt  (run it in arm64el)
>> aarch64_be-linux-gnu-gcc test.c -o test_be -static -lrt  (run it in arm64eb)
>>
>> I think it's related to the sdk which I use:
>> aarch64-linux-gnu-gcc is compiled by libc-2.20.so and aarch64_be-linux-gnu-gcc is compiled by libc-2.17.so;
>>
>> Is it a bug in glibc 2.20 ?
>> Thanks for your help.
>>
>>
>> Trace it:
>> strace ./test_be
>> execve("./test_be", ["./test_be"], [/* 17 vars */]) = 0
>> uname({sys="Linux", node="linux", ...}) = 0
>> brk(0)                                  = 0x27586000
>> brk(0x27586f60)                         = 0x27586f60
>> readlinkat(AT_FDCWD, "/proc/self/exe", "/tmp/test_be", 4096) = 12
>> brk(0x275a7f60)                         = 0x275a7f60
>> brk(0x275a8000)                         = 0x275a8000
>> statfs64("/dev/shm/", {f_type=0x1021994, f_bsize=4096, f_blocks=374412, f_bfree=374412, f_bavail=374412, f_files=374412, f_ffree=374411, f_fsid={0, 0}, f_namelen=255, f_frsize=4096}) = 0
>> dup(2)                                  = 3
>> fcntl(3, F_GETFL)                       = 0x20002 (flags O_RDWR|0x20000)
>> fstat(3, {st_mode=S_IFCHR|0600, st_rdev=makedev(4, 64), ...}) = 0
>> ioctl(3, SNDCTL_TMR_TIMEBASE or SNDRV_TIMER_IOCTL_NEXT_DEVICE or TCGETS, {B115200 opost isig icanon echo ...}) = 0
>> mmap(NULL, 65536, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f957f2000
>> write(3, "shm_open fail\n", 14shm_open fail
>> )         = 14
>> write(3, ": Invalid argument\n", 19: Invalid argument
>> )    = 19
>> close(3)                                = 0
>> munmap(0x7f957f2000, 65536)             = 0
>> fstat(1, {st_mode=S_IFCHR|0600, st_rdev=makedev(4, 64), ...}) = 0
>> ioctl(1, SNDCTL_TMR_TIMEBASE or SNDRV_TIMER_IOCTL_NEXT_DEVICE or TCGETS, {B115200 opost isig icanon echo ...}) = 0
>> mmap(NULL, 65536, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x7f957f2000
>> write(1, "errno=22, EINVAL:22\n", 20errno=22, EINVAL:22
>> )   = 20
>> exit_group(1)                           = ?
>> +++ exited with 1 +++
>>
>>
>>
>> strace ./test
>> execve("./test", ["./test"], [/* 18 vars */]) = 0
>> uname({sys="Linux", node="localhost", ...}) = 0
>> brk(0)                                  = 0x3a31000
>> brk(0x3a31f58)                          = 0x3a31f58
>> brk(0x3a52f58)                          = 0x3a52f58
>> brk(0x3a53000)                          = 0x3a53000
>> rt_sigprocmask(SIG_BLOCK, NULL, [], 8)  = 0
>> statfs64("/dev/shm/", {f_type=0x1021994, f_bsize=4096, f_blocks=1021184, f_bfree=1021184, f_bavail=1021184, f_files=1021184, f_ffree=1021182, f_fsid={0, 0}, f_namelen=255, f_frsize=4096}) = 0
>> openat(AT_FDCWD, "/dev/shm/./a", O_RDWR|O_CREAT|O_NOFOLLOW|O_CLOEXEC, 0700) = 3
>> exit_group(0)                           = ?
>> +++ exited with 0 +++
>>
> 
> Since the be version is failing before the openat syscall, the SHM_GET_NAME at
> sysdeps/posix/shm_open.c:35 is issuing an EINVAL. The macro is defined at
> sysdeps/posix/shm-directory.h and I think the relevant snippet is:
> 
>  52   while (name[0] == '/')                                                      \
>  53     ++name;                                                                   \
>  54   size_t namelen = strlen (name) + 1;                                         \
>  55   /* Validate the filename.  */                                               \
>  56   if (namelen == 1 || namelen >= NAME_MAX || strchr (name, '/') != NULL)      \
>  57     {                                                                         \
>  58       __set_errno (errno_for_invalid);                                        \
>  59       return retval_for_invalid;                                              \
>  60     }   
> 
> So I presume something might be wrong with these evaluations.  I do not have access
> to a aarch64-be environment, but since you build statically it would be easier to
> try debug it. You could try break in shm_open and check the results of the strlen
> and strchr for the name variable to see if something is wrong with these routines
> for BE (aarch64 provides optimized assembly implementation for both).
> 
> .
> 
Thank you for your help. Maybe my operation is wrong .