quoted text > Steps to reproduce:
> A short program that calls open on /dev/stdin:
>
> cat open_stdin.c
> #include <stdio.h>
> #include <stdlib.h>
> #include <sys/types.h>
> #include <sys/stat.h>
> #include <fcntl.h>
>
> int main(int argc, char **argv) {
> open("/dev/stdin",O_RDONLY);
> return 0;
> }
>
> tracing system calls with normal operation shows that this completes
> successfully. But:
>
> chmod -r open_stdin
> strace ./open_stdin
> execve("./open_stdin", ["./open_stdin"], [/* 96 vars */]) = 0
> brk(0) = 0x501000
> mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) =
> 0x2b25d01b6000
> uname({sys="Linux", node="lush", ...}) = 0
> access("/etc/ld.so.preload", R_OK) = -1 ENOENT (No such file or directory)
> ... (open's on .so's deleted) ...
> open("/etc/ld.so.cache", O_RDONLY) = 3
> fstat(3, {st_mode=S_IFREG|0644, st_size=158841, ...}) = 0
> mmap(NULL, 158841, PROT_READ, MAP_PRIVATE, 3, 0) = 0x2b25d01b7000
> close(3) = 0
> open("/lib64/libc.so.6", O_RDONLY) = 3
> read(3, "7ELF__PLACEHOLDER__1___PLACEHOLDER__1___PLACEHOLDER__1___PLACEHOLDER__1___PLACEHOLDER__1___PLACEHOLDER__1___PLACEHOLDER__1___PLACEHOLDER__1___PLACEHOLDER__1___PLACEHOLDER__1_>__PLACEHOLDER__1___PLACEHOLDER__1___PLACEHOLDER__1___PLACEHOLDER__1_P2__PLACEHOLDER__1_"..., 832) =
> 832
> fstat(3, {st_mode=S_IFREG|0755, st_size=1475924, ...}) = 0
> mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) =
> 0x2b25d01de000
> mmap(NULL, 2289896, PROT_READ|PROT_EXEC, MAP_PRIVATE|MAP_DENYWRITE, 3, 0) =
> 0x2b25d02b8000
> madvise(0x2b25d02b8000, 2289896, MADV_SEQUENTIAL|0x1) = 0
> mprotect(0x2b25d03df000, 1044480, PROT_NONE) = 0
> mmap(0x2b25d04de000, 20480, PROT_READ|PROT_WRITE,
> MAP_PRIVATE|MAP_FIXED|MAP_DENYWRITE, 3, 0x126000) = 0x2b25d04de000
> mmap(0x2b25d04e3000, 16616, PROT_READ|PROT_WRITE,
> MAP_PRIVATE|MAP_FIXED|MAP_ANONYMOUS, -1, 0) = 0x2b25d04e3000close(3)
> = 0
> mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) =
> 0x2b25d04e8000
> arch_prctl(ARCH_SET_FS, 0x2b25d04e86d0) = 0
> mprotect(0x2b25d04de000, 12288, PROT_READ) = 0
> munmap(0x2b25d01b7000, 158841) = 0
> open("/dev/stdin", O_RDONLY) = -1 EACCES (Permission denied)
>
>
> The last line shows a Permission denied error on opening /dev/stdin. If a
> normal filesystem (i.e. not-/dev/) filename is used, the open works normally.
>
> I have reproduced this on 2.4 and 2.6 kernels
> Just a guess here: is an error flag from attempting to read the binary not
> getting cleared and is being reported when trying to open stdin?
>
