as the menu is displayed, the window might go away or change its
label causing menuhit() to dereference bad memory. just strdup()
the labels before passing to menu3str to prevent accidents.
avoid double entries in the cache for copen() and properly handle
locking so we wont just give up if we cant lock the Mntcache entry,
but drop the cache lock, qlock the Mntcache entry, and then recheck
the cache.
general cleanup (cdev -> ccache, use eqchantdqid())
the lock order of page.Lock -> palloc.hashlock was
violated in cachedel() which is called from the
pager. change the code to do it in the right oder
to prevent deadlock.
change lookpage to retry on false hit. i assume that
a false hit means:
a) we'r low on memory -> cached page got uncached/reused
b) duppage() got called on the page, meaning theres another
cached copy in the image now.
paging in is expensive compared to the hashtable lookup, so
i think retrying is better.
cleanup fixfault, adding comments.
swaped pages use a 8bit refcount where as the Page uses a 16bit one.
this might be exploited with having a process having a single page
swaped out and then forking 255 times to make the swap map refcount
overflow and panic the kernel.
this condition is probably very rare. so instead of doubling the
size of the swap map, we add a single 32bit refcount swapalloc.xref
which will keep the combined refcount of all swap map entries who
exceeded 255 references.
zero swapimage.c in setswapchan() after closing it as the stat() call
below might error leaving a dangeling pointer.
attachimage()'s approach to handling newseg() error is flawed:
a) the the image is on the hash table, but ref is still 0, and
there is no segment/pages attached to it so nobody is going to
reclaim / putimage() it -> leak
b) calling pexit() would deadlock us because exec has acquired
up->seglock when calling attachimage(), so this would just deadlock.
the fix does the following:
attachimage() will putimage() and nexterror() if newseg() fails
instead of pexit(). this is less surprising.
exec now keeps the condition variable commit which is set once
we are commited / reached the point of no return and check this
variable in the highest waserror() handler and pexit() us there.
this way we have released up all the locks and pexit() will
cleanup.
note: this bug shouldnt us hit in with the current newseg()
implementation as it uses smalloc() which would wait to
satisfy the allocation instead of erroring.
kstrcpy() did not null terminate for < 4 byte buffers. fixed,
but i dont think there is any case where this can happen in
practice.
always set malloctag in kstrdup(), cleanup.
always use ERRMAX bounded kstrcpy() to set up->errstr, q->err
and note[]->msg. paranoia.
instead of silently truncating interface name in netifinit(),
panic the kernel if interface name is too long as this case
is clearly a mistake.
panic kernel when filename is too long for addbootfile() in
devroot. this might happen if your kernel configuration is
messed up.
