/*
 * netsniff-ng - the packet sniffing beast
 * Copyright 2012 Markus Amend <markus@netsniff-ng.org>, Deutsche Flugsicherung GmbH
 * Subject to the GPL, version 2.
 *
 * IPv6 Hop-By-Hop Header described in RFC2460
 */

#include <stdio.h>
#include <stdint.h>
#include <netinet/in.h>    /* for ntohs() */

#include "proto.h"
#include "dissector_eth.h"
#include "built_in.h"
#include "pkt_buff.h"

struct hop_by_hophdr {
	uint8_t h_next_header;
	uint8_t hdr_len;
} __packed;

static void dissect_opt_hop(struct pkt_buff *pkt __maybe_unused,
			    ssize_t *opt_len)
{
	/* Have to been upgraded.
	 * http://tools.ietf.org/html/rfc2460#section-4.2
	 * Look also for proto_ipv6_dest_opts.h, it needs
	 * dissect_opt(), too.
	 */
	if (*opt_len)
		tprintf(", Option(s) recognized ");

	/* If adding dissector reduce opt_len for each using of pkt_pull
	 * to the same size.
	 */
}

static void hop_by_hop(struct pkt_buff *pkt)
{
	uint16_t hdr_ext_len;
	ssize_t opt_len;
	struct hop_by_hophdr *hop_ops;

	hop_ops = (struct hop_by_hophdr *) pkt_pull(pkt, sizeof(*hop_ops));
	if (hop_ops == NULL)
		return;

	/* Total Header Length in Bytes */
	hdr_ext_len = (hop_ops->hdr_len + 1) * 8;
	/* Options length in Bytes */
	opt_len = hdr_ext_len - sizeof(*hop_ops);

	tprintf("\t [ Hop-by-Hop Options ");
	tprintf("NextHdr (%u), ", hop_ops->h_next_header);
	if (opt_len > pkt_len(pkt) || opt_len < 0){
		tprintf("HdrExtLen (%u, %u Bytes, %s)", hop_ops->hdr_len,
		      hdr_ext_len, colorize_start_full(black, red)
		      "invalid" colorize_end());
		      return;
	}
	tprintf("HdrExtLen (%u, %u Bytes)", hop_ops->hdr_len,
		hdr_ext_len);

	dissect_opt_hop(pkt, &opt_len);

	tprintf(" ]\n");

	pkt_pull(pkt, opt_len);
	pkt_set_dissector(pkt, &eth_lay3, hop_ops->h_next_header);
}

static void hop_by_hop_less(struct pkt_buff *pkt)
{
	uint16_t hdr_ext_len;
	ssize_t opt_len;
	struct hop_by_hophdr *hop_ops;

	hop_ops = (struct hop_by_hophdr *) pkt_pull(pkt, sizeof(*hop_ops));
	if (hop_ops == NULL)
		return;

	/* Total Header Length in Bytes */
	hdr_ext_len = (hop_ops->hdr_len + 1) * 8;
	/* Options length in Bytes */
	opt_len = hdr_ext_len - sizeof(*hop_ops);
	if (opt_len > pkt_len(pkt) || opt_len < 0)
		return;

	tprintf(" Hop Ops");

	pkt_pull(pkt, opt_len);
	pkt_set_dissector(pkt, &eth_lay3, hop_ops->h_next_header);
}

struct protocol ipv6_hop_by_hop_ops = {
	.key = 0x0,
	.print_full = hop_by_hop,
	.print_less = hop_by_hop_less,
};
ion value='committer'>committer</option>
<option value='range'>range</option>
</select>
<input class='txt' type='search' size='10' name='q' value=''/>
<input type='submit' value='search'/>
</form>
</td></tr></table>
<div class='path'>path: <a href='/cgit.cgi/linux/net-next.git/diff/?id=f9a42e0d58cf0fe3d902e63d4582f2ea4cd2bb8b'>root</a>/<a href='/cgit.cgi/linux/net-next.git/diff/include?id=f9a42e0d58cf0fe3d902e63d4582f2ea4cd2bb8b'>include</a>/<a href='/cgit.cgi/linux/net-next.git/diff/include/uapi?id=f9a42e0d58cf0fe3d902e63d4582f2ea4cd2bb8b'>uapi</a>/<a href='/cgit.cgi/linux/net-next.git/diff/include/uapi/asm-generic?id=f9a42e0d58cf0fe3d902e63d4582f2ea4cd2bb8b'>asm-generic</a>/<a href='/cgit.cgi/linux/net-next.git/diff/include/uapi/asm-generic/poll.h?id=f9a42e0d58cf0fe3d902e63d4582f2ea4cd2bb8b'>poll.h</a></div><div class='content'><div class='cgit-panel'><b>diff options</b><form method='get'><input type='hidden' name='id' value='f9a42e0d58cf0fe3d902e63d4582f2ea4cd2bb8b'/><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><div class='diffstat-header'><a href='/cgit.cgi/linux/net-next.git/diff/?id=f9a42e0d58cf0fe3d902e63d4582f2ea4cd2bb8b'>Diffstat</a> (limited to 'include/uapi/asm-generic/poll.h')</div><table summary='diffstat' class='diffstat'>>Tejun Heo &lt;tj@kernel.org&gt;</td><td class='right'>2017-01-28 07:49:42 -0500</td></tr>
<tr><th>commit</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/include/net/caif/cfctrl.h?id=966d2b04e070bc040319aaebfec09e0144dc3341'>966d2b04e070bc040319aaebfec09e0144dc3341</a> (<a href='/cgit.cgi/linux/net-next.git/patch/include/net/caif/cfctrl.h?id=966d2b04e070bc040319aaebfec09e0144dc3341'>patch</a>)</td></tr>
<tr><th>tree</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/tree/?id=966d2b04e070bc040319aaebfec09e0144dc3341'>4b96156e3d1dd4dfd6039b7c219c9dc4616da52d</a> /<a href='/cgit.cgi/linux/net-next.git/tree/include/net/caif/cfctrl.h?id=966d2b04e070bc040319aaebfec09e0144dc3341'>include/net/caif/cfctrl.h</a></td></tr>
<tr><th>parent</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/include/net/caif/cfctrl.h?id=1b1bc42c1692e9b62756323c675a44cb1a1f9dbd'>1b1bc42c1692e9b62756323c675a44cb1a1f9dbd</a> (<a href='/cgit.cgi/linux/net-next.git/diff/include/net/caif/cfctrl.h?id=966d2b04e070bc040319aaebfec09e0144dc3341&amp;id2=1b1bc42c1692e9b62756323c675a44cb1a1f9dbd'>diff</a>)</td></tr></table>
<div class='commit-subject'>percpu-refcount: fix reference leak during percpu-atomic transition</div><div class='commit-msg'>percpu_ref_tryget() and percpu_ref_tryget_live() should return
"true" IFF they acquire a reference. But the return value from
atomic_long_inc_not_zero() is a long and may have high bits set,
e.g. PERCPU_COUNT_BIAS, and the return value of the tryget routines
is bool so the reference may actually be acquired but the routines
return "false" which results in a reference leak since the caller
assumes it does not need to do a corresponding percpu_ref_put().

This was seen when performing CPU hotplug during I/O, as hangs in
blk_mq_freeze_queue_wait where percpu_ref_kill (blk_mq_freeze_queue_start)
raced with percpu_ref_tryget (blk_mq_timeout_work).
Sample stack trace:

__switch_to+0x2c0/0x450
__schedule+0x2f8/0x970
schedule+0x48/0xc0
blk_mq_freeze_queue_wait+0x94/0x120
blk_mq_queue_reinit_work+0xb8/0x180
blk_mq_queue_reinit_prepare+0x84/0xa0
cpuhp_invoke_callback+0x17c/0x600
cpuhp_up_callbacks+0x58/0x150
_cpu_up+0xf0/0x1c0
do_cpu_up+0x120/0x150
cpu_subsys_online+0x64/0xe0
device_online+0xb4/0x120
online_store+0xb4/0xc0
dev_attr_store+0x68/0xa0
sysfs_kf_write+0x80/0xb0
kernfs_fop_write+0x17c/0x250
__vfs_write+0x6c/0x1e0
vfs_write+0xd0/0x270
SyS_write+0x6c/0x110
system_call+0x38/0xe0

Examination of the queue showed a single reference (no PERCPU_COUNT_BIAS,
and __PERCPU_REF_DEAD, __PERCPU_REF_ATOMIC set) and no requests.
However, conditions at the time of the race are count of PERCPU_COUNT_BIAS + 0
and __PERCPU_REF_DEAD and __PERCPU_REF_ATOMIC set.

The fix is to make the tryget routines use an actual boolean internally instead
of the atomic long result truncated to a int.

Fixes: e625305b3907 percpu-refcount: make percpu_ref based on longs instead of ints
Link: https://bugzilla.kernel.org/show_bug.cgi?id=190751
Signed-off-by: Douglas Miller &lt;dougmill@linux.vnet.ibm.com&gt;
Reviewed-by: Jens Axboe &lt;axboe@fb.com&gt;
Signed-off-by: Tejun Heo &lt;tj@kernel.org&gt;
Fixes: e625305b3907 ("percpu-refcount: make percpu_ref based on longs instead of ints")
Cc: stable@vger.kernel.org # v3.18+
</div><div class='diffstat-header'><a href='/cgit.cgi/linux/net-next.git/diff/?id=966d2b04e070bc040319aaebfec09e0144dc3341'>Diffstat</a> (limited to 'include/net/caif/cfctrl.h')</div><table summary='diffstat' class='diffstat'>