bug#12478: cat SEGV when I press Ctrl-Alt-SysRq-1 on text console

[Rafal W.]

> $ cat /dev/zero
> ^\Quit (core dumped)
>
> Steps to reproduce:
> 1. Switch to any text console (it doesn't happen in X).
> 2. Login
> 3. Run: cat /dev/zero
> 4. Press: Ctrl-Alt-SysRq-1 (or any number except letters:)
> 5. You'll see: ^\Quit (core dumped)
>
> Here is the backtrace:
> address@hidden:/usr/src/coreutils-8.13/src$ gdb ./cat
> GNU gdb (Ubuntu/Linaro 7.4-2012.04-0ubuntu2) 7.4-2012.04
> Copyright (C) 2012 Free Software Foundation, Inc.
> License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
> This is free software: you are free to change and redistribute it.
> There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
> and "show warranty" for details.
> This GDB was configured as "x86_64-linux-gnu".
> For bug reporting instructions, please see:
> <http://bugs.launchpad.net/gdb-linaro/>...
> Reading symbols from /usr/src/coreutils-8.13/src/cat...done.
> (gdb) set args /dev/zero
> (gdb) run
> Starting program: /usr/src/coreutils-8.13/src/cat /dev/zero
> ^\
> Program received signal SIGQUIT, Quit.
> 0x00007ffff7b02100 in __write_nocancel () at 
> ../sysdeps/unix/syscall-template.S:82
> 82      ../sysdeps/unix/syscall-template.S: No such file or directory.
> (gdb) bt
> #0  0x00007ffff7b02100 in __write_nocancel () at 
> ../sysdeps/unix/syscall-template.S:82
> #1  0x0000000000405184 in safe_write (fd=1, buf=0x60f000, count=32768) at 
> safe-read.c:66
> #2  0x0000000000402dba in full_write (fd=1, buf=0x60f000, count=32768) at 
> full-write.c:65
> #3  0x0000000000401e0e in simple_cat (buf=0x60f000 "", bufsize=32768) at 
> cat.c:186
> #4  0x0000000000402958 in main (argc=2, argv=0x7fffffffe088) at cat.c:731
> (gdb) bt full
> #0  0x00007ffff7b02100 in __write_nocancel () at 
> ../sysdeps/unix/syscall-template.S:82
> No locals.
> #1  0x0000000000405184 in safe_write (fd=1, buf=0x60f000, count=32768) at 
> safe-read.c:66
>        result = 32768
> #2  0x0000000000402dba in full_write (fd=1, buf=0x60f000, count=32768) at 
> full-write.c:65
>        n_rw = 32768
>        total = 0
>        ptr = 0x60f000 ""
> #3  0x0000000000401e0e in simple_cat (buf=0x60f000 "", bufsize=32768) at 
> cat.c:186
>        n = 32768
>        n_read = 32768
> #4  0x0000000000402958 in main (argc=2, argv=0x7fffffffe088) at cat.c:731
>        outsize = 32768
>        insize = 32768
>        page_size = 4096
>        inbuf = 0x60ef90 ""
>        outbuf = 0x0
>        ok = true
>        c = -1
>        argind = 1
>        out_dev = 15774435
>        out_ino = 9
>        check_redirection = false
>        have_read_stdin = false
>        stat_buf = {st_dev = 5, st_ino = 1031, st_nlink = 1, st_mode = 8630, 
> st_uid = 0, st_gid = 0, __pad0 = 0, st_rdev = 261, st_size = 0, st_blksize = 
> 4096, st_blocks = 0, st_atim = {tv_sec = 1348073751, tv_nsec = 756796048},
>          st_mtim = {tv_sec = 1348073751, tv_nsec = 756796048}, st_ctim = 
> {tv_sec = 1348073751, tv_nsec = 756796048}, __unused = {0, 0, 0}}
>        number = false
>        number_nonblank = false
>        squeeze_blank = false
>        show_ends = false
>        show_nonprinting = false
>        show_tabs = false
>        file_open_mode = 0
>        long_options = {{name = 0x409810 "number-nonblank", has_arg = 0, flag 
> = 0x0, val = 98}, {name = 0x409820 "number", has_arg = 0, flag = 0x0, val = 
> 110}, {name = 0x409827 "squeeze-blank", has_arg = 0, flag = 0x0, val = 115}, {
>            name = 0x409835 "show-nonprinting", has_arg = 0, flag = 0x0, val = 
> 118}, {name = 0x409846 "show-ends", has_arg = 0, flag = 0x0, val = 69}, {name 
> = 0x409850 "show-tabs", has_arg = 0, flag = 0x0, val = 84}, {
>            name = 0x40985a "show-all", has_arg = 0, flag = 0x0, val = 65}, 
> {name = 0x409863 "help", has_arg = 0, flag = 0x0, val = -130}, {name = 
> 0x409868 "version", has_arg = 0, flag = 0x0, val = -131}, {name = 0x0, 
> has_arg = 0,
>            flag = 0x0, val = 0}}
> (gdb)
>
> It's a cat bug, or libc?
>