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SubjectRe: Bug in set/gethostname.
Hi guys,

Linus writes ...

asmlinkage int sys_gethostname(char *name, int len)
{
- int i;
+ int i, errno;
if (len < 0)
return -EINVAL;
i = 1 + strlen(system_utsname.nodename);
if (i > len)
i = len;
- return copy_to_user(name, system_utsname.nodename, i) ? -EFAULT : 0;
+ down(&uts_sem);
+ errno = 0;
+ if (copy_to_user(name, system_utsname.nodename, i))
+ errno = -EFAULT;
+ up(&uts_sem);
+ return errno;
}
In my humble opinion, sys_gethostname should acquire the semaphore
before calling strlen on system_utsname.nodename. That way, gethostname
will return either the old name or the new name, but not some mongrel
mixture of the two.

Also, system_utsname is used in a bunch of other places. These places
look like they actually read or write it:

arch/alpha/kernel/osf_sys.c
arch/arm/kernel/sys_arm.c
arch/i386/kernel/sys_i386.c
arch/mips/kernel/syscall.c
arch/ppc/kernel/syscalls.c
arch/sparc/kernel/sys_sparc.c
arch/sparc/kernel/sys_sunos.c
arch/sparc64/kernel/sys_sparc.c
arch/sparc64/kernel/sys_sunos32.c
arch/sparc64/solaris/misc.c
drivers/char/random.c
drivers/sound/soundcard.c
fs/lockd/clntproc.c
fs/lockd/mon.c
fs/nfs/nfsroot.c
kernel/sys.c
kernel/sysctl.c
net/ipv4/ipconfig.c
net/sunrpc/auth_unix.c

Cheers,

Michael Chastain
<mailto:mec@shout.net>
"love without fear"

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