Commit 8febdd85 authored by Linus Torvalds's avatar Linus Torvalds
Browse files

sysctl: don't overflow the user-supplied buffer with '\0'

If the string was too long to fit in the user-supplied buffer,
the sysctl layer would zero-terminate it by writing past the
end of the buffer. Don't do that.

Noticed by Yi Yang <>
Signed-off-by: default avatarLinus Torvalds <>
parent 8b90db0d
......@@ -2201,14 +2201,12 @@ int sysctl_string(ctl_table *table, int __user *name, int nlen,
if (get_user(len, oldlenp))
return -EFAULT;
if (len) {
l = strlen(table->data);
l = strlen(table->data)+1;
if (len > l) len = l;
if (len >= table->maxlen)
len = table->maxlen;
if(copy_to_user(oldval, table->data, len))
return -EFAULT;
if(put_user(0, ((char __user *) oldval) + len))
return -EFAULT;
if(put_user(len, oldlenp))
return -EFAULT;
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