/*
 * netsniff-ng - the packet sniffing beast
 * Copyright 2009, 2010 Daniel Borkmann.
 * Copyright 2013 Tobias Klauser.
 * Subject to the GPL, version 2.
 */

#define _BSD_SOURCE
#include <ctype.h>
#include <stdio.h>
#include <stdarg.h>
#include <sys/ioctl.h>

#include "tprintf.h"
#include "die.h"
#include "locking.h"
#include "built_in.h"

#define term_trailing_size	5
#define term_starting_size	3

#define term_curr_size		(get_tty_size() - term_trailing_size)

static char buffer[1024];

static volatile size_t buffer_use = 0;

static struct spinlock buffer_lock;

static int get_tty_size(void)
{
#ifdef TIOCGSIZE
	struct ttysize ts = {0};

	return (ioctl(0, TIOCGSIZE, &ts) == 0 ?	ts.ts_cols : DEFAULT_TTY_SIZE);
#elif defined(TIOCGWINSZ)
	struct winsize ts;

	return (ioctl(0, TIOCGWINSZ, &ts) == 0 ? ts.ws_col : DEFAULT_TTY_SIZE);
#else
	return DEFAULT_TTY_SIZE;
#endif
}

static inline void __tprintf_flush_newline(void)
{
	int i;

	fputc('\n', stdout);
	for (i = 0; i < term_starting_size; ++i)
		fputc(' ', stdout);
}

static inline int __tprintf_flush_skip(char *buf, int i)
{
	int val = buf[i];

	if (val == ' ' || val == ',')
		return 1;

	return 0;
}

static void __tprintf_flush(void)
{
	size_t i;
	static ssize_t line_count = 0;
	ssize_t term_len = term_curr_size;

	for (i = 0; i < buffer_use; ++i) {
		if (buffer[i] == '\n') {
			term_len = term_curr_size;
			line_count = -1;
		}

		if (line_count == term_len) {
			__tprintf_flush_newline();
			line_count = term_starting_size;

			while (i < buffer_use &&
			       __tprintf_flush_skip(buffer, i))
				i++;
		}

		fputc(buffer[i], stdout);
		line_count++;
	}

	fflush(stdout);
	buffer_use = 0;
}

void tprintf_flush(void)
{
	spinlock_lock(&buffer_lock);
	__tprintf_flush();
	spinlock_unlock(&buffer_lock);
}

void tprintf_init(void)
{
	spinlock_init(&buffer_lock);

	setvbuf(stdout, NULL, _IONBF, 0);
	setvbuf(stderr, NULL, _IONBF, 0);
}

void tprintf_cleanup(void)
{
	tprintf_flush();
	spinlock_destroy(&buffer_lock);
}

void tprintf(char *msg, ...)
{
	ssize_t ret;
	ssize_t avail;
	va_list vl;

	spinlock_lock(&buffer_lock);

	avail = sizeof(buffer) - buffer_use;
	bug_on(avail < 0);

	va_start(vl, msg);
	ret = vsnprintf(buffer + buffer_use, avail, msg, vl);
	va_end(vl);

	if (ret < 0)
		panic("vsnprintf screwed up in tprintf!\n");
	if ((size_t) ret > sizeof(buffer))
		panic("No mem in tprintf left!\n");
	if (ret >= avail) {
		__tprintf_flush();

		avail = sizeof(buffer) - buffer_use;
		bug_on(avail < 0);

		va_start(vl, msg);
		ret = vsnprintf(buffer + buffer_use, avail, msg, vl);
		va_end(vl);

		if (ret < 0)
			panic("vsnprintf screwed up in tprintf!\n");
	}

	buffer_use += ret;

	spinlock_unlock(&buffer_lock);
}

void tputchar_safe(int c)
{
	unsigned char ch = (unsigned char)(c & 0xff);

	if (isprint(ch))
		tprintf("%c", ch);
	else
		tprintf("\\0x%02x", ch);
}

void tputs_safe(const char *str, size_t len)
{
	while (len--) {
		tputchar_safe(*str);
		str++;
	}
}
nux/net-next.git/commit/sound/soc?id=ea07b862ac8ef9b8c8358517d2e39f847dda6659'>soc</a>/<a href='/cgit.cgi/linux/net-next.git/commit/sound/soc/sh?id=ea07b862ac8ef9b8c8358517d2e39f847dda6659'>sh</a>/<a href='/cgit.cgi/linux/net-next.git/commit/sound/soc/sh/rcar?id=ea07b862ac8ef9b8c8358517d2e39f847dda6659'>rcar</a>/<a href='/cgit.cgi/linux/net-next.git/commit/sound/soc/sh/rcar/Makefile?id=ea07b862ac8ef9b8c8358517d2e39f847dda6659'>Makefile</a></div><div class='content'><div class='cgit-panel'><b>diff options</b><form method='get'><input type='hidden' name='id' value='ea07b862ac8ef9b8c8358517d2e39f847dda6659'/><table><tr><td colspan='2'/></tr><tr><td class='label'>context:</td><td class='ctrl'><select name='context' onchange='this.form.submit();'><option value='1'>1</option><option value='2'>2</option><option value='3' selected='selected'>3</option><option value='4'>4</option><option value='5'>5</option><option value='6'>6</option><option value='7'>7</option><option value='8'>8</option><option value='9'>9</option><option value='10'>10</option><option value='15'>15</option><option value='20'>20</option><option value='25'>25</option><option value='30'>30</option><option value='35'>35</option><option value='40'>40</option></select></td></tr><tr><td class='label'>space:</td><td class='ctrl'><select name='ignorews' onchange='this.form.submit();'><option value='0' selected='selected'>include</option><option value='1'>ignore</option></select></td></tr><tr><td class='label'>mode:</td><td class='ctrl'><select name='dt' onchange='this.form.submit();'><option value='0' selected='selected'>unified</option><option value='1'>ssdiff</option><option value='2'>stat only</option></select></td></tr><tr><td/><td class='ctrl'><noscript><input type='submit' value='reload'/></noscript></td></tr></table></form></div><table summary='commit info' class='commit-info'>
<tr><th>author</th><td>Johannes Weiner &lt;hannes@cmpxchg.org&gt;</td><td class='right'>2017-01-06 19:21:43 -0500</td></tr>
<tr><th>committer</th><td>Linus Torvalds &lt;torvalds@linux-foundation.org&gt;</td><td class='right'>2017-01-07 18:22:40 -0800</td></tr>
<tr><th>commit</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/sound/soc/sh/rcar/Makefile?id=ea07b862ac8ef9b8c8358517d2e39f847dda6659'>ea07b862ac8ef9b8c8358517d2e39f847dda6659</a> (<a href='/cgit.cgi/linux/net-next.git/patch/sound/soc/sh/rcar/Makefile?id=ea07b862ac8ef9b8c8358517d2e39f847dda6659'>patch</a>)</td></tr>
<tr><th>tree</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/tree/?id=ea07b862ac8ef9b8c8358517d2e39f847dda6659'>a1db46e9dd5dcf4c26dca819fad0b69fbb37e073</a> /<a href='/cgit.cgi/linux/net-next.git/tree/sound/soc/sh/rcar/Makefile?id=ea07b862ac8ef9b8c8358517d2e39f847dda6659'>sound/soc/sh/rcar/Makefile</a></td></tr>
<tr><th>parent</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/sound/soc/sh/rcar/Makefile?id=b0b9b3df27d100a975b4e8818f35382b64a5e35c'>b0b9b3df27d100a975b4e8818f35382b64a5e35c</a> (<a href='/cgit.cgi/linux/net-next.git/diff/sound/soc/sh/rcar/Makefile?id=ea07b862ac8ef9b8c8358517d2e39f847dda6659&amp;id2=b0b9b3df27d100a975b4e8818f35382b64a5e35c'>diff</a>)</td></tr></table>
<div class='commit-subject'>mm: workingset: fix use-after-free in shadow node shrinker</div><div class='commit-msg'>Several people report seeing warnings about inconsistent radix tree
nodes followed by crashes in the workingset code, which all looked like
use-after-free access from the shadow node shrinker.

Dave Jones managed to reproduce the issue with a debug patch applied,
which confirmed that the radix tree shrinking indeed frees shadow nodes
while they are still linked to the shadow LRU:

  WARNING: CPU: 2 PID: 53 at lib/radix-tree.c:643 delete_node+0x1e4/0x200
  CPU: 2 PID: 53 Comm: kswapd0 Not tainted 4.10.0-rc2-think+ #3
  Call Trace:
     delete_node+0x1e4/0x200
     __radix_tree_delete_node+0xd/0x10
     shadow_lru_isolate+0xe6/0x220
     __list_lru_walk_one.isra.4+0x9b/0x190
     list_lru_walk_one+0x23/0x30
     scan_shadow_nodes+0x2e/0x40
     shrink_slab.part.44+0x23d/0x5d0
     shrink_node+0x22c/0x330
     kswapd+0x392/0x8f0

This is the WARN_ON_ONCE(!list_empty(&amp;node-&gt;private_list)) placed in the
inlined radix_tree_shrink().

The problem is with 14b468791fa9 ("mm: workingset: move shadow entry
tracking to radix tree exceptional tracking"), which passes an update
callback into the radix tree to link and unlink shadow leaf nodes when
tree entries change, but forgot to pass the callback when reclaiming a
shadow node.

While the reclaimed shadow node itself is unlinked by the shrinker, its
deletion from the tree can cause the left-most leaf node in the tree to
be shrunk.  If that happens to be a shadow node as well, we don't unlink
it from the LRU as we should.

Consider this tree, where the s are shadow entries:

       root-&gt;rnode
            |
       [0       n]
        |       |
     [s    ] [sssss]

Now the shadow node shrinker reclaims the rightmost leaf node through
the shadow node LRU:

       root-&gt;rnode
            |
       [0        ]
        |
    [s     ]

Because the parent of the deleted node is the first level below the
root and has only one child in the left-most slot, the intermediate
level is shrunk and the node containing the single shadow is put in
its place:

       root-&gt;rnode
            |
       [s        ]

The shrinker again sees a single left-most slot in a first level node
and thus decides to store the shadow in root-&gt;rnode directly and free
the node - which is a leaf node on the shadow node LRU.

  root-&gt;rnode
       |
       s

Without the update callback, the freed node remains on the shadow LRU,
where it causes later shrinker runs to crash.

Pass the node updater callback into __radix_tree_delete_node() in case
the deletion causes the left-most branch in the tree to collapse too.

Also add warnings when linked nodes are freed right away, rather than
wait for the use-after-free when the list is scanned much later.

Fixes: 14b468791fa9 ("mm: workingset: move shadow entry tracking to radix tree exceptional tracking")
Reported-by: Dave Chinner &lt;david@fromorbit.com&gt;
Reported-by: Hugh Dickins &lt;hughd@google.com&gt;
Reported-by: Andrea Arcangeli &lt;aarcange@redhat.com&gt;
Reported-and-tested-by: Dave Jones &lt;davej@codemonkey.org.uk&gt;
Signed-off-by: Johannes Weiner &lt;hannes@cmpxchg.org&gt;
Cc: Christoph Hellwig &lt;hch@lst.de&gt;
Cc: Chris Leech &lt;cleech@redhat.com&gt;
Cc: Lee Duncan &lt;lduncan@suse.com&gt;
Cc: Jan Kara &lt;jack@suse.cz&gt;
Cc: Kirill A. Shutemov &lt;kirill.shutemov@linux.intel.com&gt;
Cc: Matthew Wilcox &lt;mawilcox@linuxonhyperv.com&gt;
Cc: Andrew Morton &lt;akpm@linux-foundation.org&gt;
Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</div><div class='diffstat-header'><a href='/cgit.cgi/linux/net-next.git/diff/?id=ea07b862ac8ef9b8c8358517d2e39f847dda6659'>Diffstat</a> (limited to 'sound/soc/sh/rcar/Makefile')</div><table summary='diffstat' class='diffstat'>