From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Gratian Crisan <gratian.crisan@ni.com>,
"Peter Zijlstra (Intel)" <peterz@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
dvhart@infradead.org, Ben Hutchings <ben@decadent.org.uk>
Subject: [PATCH 4.9 05/41] futex: Fix pi_state->owner serialization
Date: Fri, 5 Mar 2021 13:22:12 +0100 [thread overview]
Message-ID: <20210305120851.538190367@linuxfoundation.org> (raw)
In-Reply-To: <20210305120851.255002428@linuxfoundation.org>
From: Ben Hutchings <ben@decadent.org.uk>
From: Peter Zijlstra <peterz@infradead.org>
commit c74aef2d06a9f59cece89093eecc552933cba72a upstream.
There was a reported suspicion about a race between exit_pi_state_list()
and put_pi_state(). The same report mentioned the comment with
put_pi_state() said it should be called with hb->lock held, and it no
longer is in all places.
As it turns out, the pi_state->owner serialization is indeed broken. As per
the new rules:
734009e96d19 ("futex: Change locking rules")
pi_state->owner should be serialized by pi_state->pi_mutex.wait_lock.
For the sites setting pi_state->owner we already hold wait_lock (where
required) but exit_pi_state_list() and put_pi_state() were not and
raced on clearing it.
Fixes: 734009e96d19 ("futex: Change locking rules")
Reported-by: Gratian Crisan <gratian.crisan@ni.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: dvhart@infradead.org
Cc: stable@vger.kernel.org
Link:
https://lkml.kernel.org/r/20170922154806.jd3ffltfk24m4o4y@hirez.programming.kicks-ass.net
[bwh: Backported to 4.9: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
kernel/futex.c | 21 ++++++++++++++-------
1 file changed, 14 insertions(+), 7 deletions(-)
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -868,8 +868,6 @@ static void get_pi_state(struct futex_pi
/*
* Drops a reference to the pi_state object and frees or caches it
* when the last reference is gone.
- *
- * Must be called with the hb lock held.
*/
static void put_pi_state(struct futex_pi_state *pi_state)
{
@@ -884,13 +882,15 @@ static void put_pi_state(struct futex_pi
* and has cleaned up the pi_state already
*/
if (pi_state->owner) {
+ raw_spin_lock_irq(&pi_state->pi_mutex.wait_lock);
pi_state_update_owner(pi_state, NULL);
rt_mutex_proxy_unlock(&pi_state->pi_mutex);
+ raw_spin_unlock_irq(&pi_state->pi_mutex.wait_lock);
}
- if (current->pi_state_cache)
+ if (current->pi_state_cache) {
kfree(pi_state);
- else {
+ } else {
/*
* pi_state->list is already empty.
* clear pi_state->owner.
@@ -949,13 +949,14 @@ static void exit_pi_state_list(struct ta
raw_spin_unlock_irq(&curr->pi_lock);
spin_lock(&hb->lock);
-
- raw_spin_lock_irq(&curr->pi_lock);
+ raw_spin_lock_irq(&pi_state->pi_mutex.wait_lock);
+ raw_spin_lock(&curr->pi_lock);
/*
* We dropped the pi-lock, so re-check whether this
* task still owns the PI-state:
*/
if (head->next != next) {
+ raw_spin_unlock(&pi_state->pi_mutex.wait_lock);
spin_unlock(&hb->lock);
continue;
}
@@ -964,9 +965,10 @@ static void exit_pi_state_list(struct ta
WARN_ON(list_empty(&pi_state->list));
list_del_init(&pi_state->list);
pi_state->owner = NULL;
- raw_spin_unlock_irq(&curr->pi_lock);
+ raw_spin_unlock(&curr->pi_lock);
get_pi_state(pi_state);
+ raw_spin_unlock_irq(&pi_state->pi_mutex.wait_lock);
spin_unlock(&hb->lock);
rt_mutex_futex_unlock(&pi_state->pi_mutex);
@@ -1349,6 +1351,10 @@ static int attach_to_pi_owner(u32 __user
WARN_ON(!list_empty(&pi_state->list));
list_add(&pi_state->list, &p->pi_state_list);
+ /*
+ * Assignment without holding pi_state->pi_mutex.wait_lock is safe
+ * because there is no concurrency as the object is not published yet.
+ */
pi_state->owner = p;
raw_spin_unlock_irq(&p->pi_lock);
@@ -3027,6 +3033,7 @@ retry:
raw_spin_lock_irq(&pi_state->pi_mutex.wait_lock);
spin_unlock(&hb->lock);
+ /* drops pi_state->pi_mutex.wait_lock */
ret = wake_futex_pi(uaddr, uval, pi_state);
put_pi_state(pi_state);
next prev parent reply other threads:[~2021-03-05 12:41 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-05 12:22 [PATCH 4.9 00/41] 4.9.260-rc1 review Greg Kroah-Hartman
2021-03-05 12:22 ` [PATCH 4.9 01/41] futex: Cleanup variable names for futex_top_waiter() Greg Kroah-Hartman
2021-03-05 12:22 ` [PATCH 4.9 02/41] futex: Cleanup refcounting Greg Kroah-Hartman
2021-03-05 12:22 ` [PATCH 4.9 03/41] futex: Pull rt_mutex_futex_unlock() out from under hb->lock Greg Kroah-Hartman
2021-03-05 12:22 ` [PATCH 4.9 04/41] futex: Futex_unlock_pi() determinism Greg Kroah-Hartman
2021-03-05 12:22 ` Greg Kroah-Hartman [this message]
2021-03-05 12:22 ` [PATCH 4.9 06/41] futex: Fix more put_pi_state() vs. exit_pi_state_list() races Greg Kroah-Hartman
2021-03-05 12:22 ` [PATCH 4.9 07/41] futex: Dont enable IRQs unconditionally in put_pi_state() Greg Kroah-Hartman
2021-03-05 12:22 ` [PATCH 4.9 08/41] net: usb: qmi_wwan: support ZTE P685M modem Greg Kroah-Hartman
2021-03-05 12:22 ` [PATCH 4.9 09/41] arm: kprobes: Allow to handle reentered kprobe on single-stepping Greg Kroah-Hartman
2021-03-05 12:22 ` [PATCH 4.9 10/41] scripts: use pkg-config to locate libcrypto Greg Kroah-Hartman
2021-03-05 12:22 ` [PATCH 4.9 11/41] scripts: set proper OpenSSL include dir also for sign-file Greg Kroah-Hartman
2021-03-05 12:22 ` [PATCH 4.9 12/41] hugetlb: fix update_and_free_page contig page struct assumption Greg Kroah-Hartman
2021-03-05 12:22 ` [PATCH 4.9 13/41] printk: fix deadlock when kernel panic Greg Kroah-Hartman
2021-03-05 12:22 ` [PATCH 4.9 14/41] arm64: Remove redundant mov from LL/SC cmpxchg Greg Kroah-Hartman
2021-03-05 12:22 ` [PATCH 4.9 15/41] arm64: Avoid redundant type conversions in xchg() and cmpxchg() Greg Kroah-Hartman
2021-03-05 12:22 ` [PATCH 4.9 16/41] arm64: cmpxchg: Use "K" instead of "L" for ll/sc immediate constraint Greg Kroah-Hartman
2021-03-05 12:22 ` [PATCH 4.9 17/41] arm64: Use correct ll/sc atomic constraints Greg Kroah-Hartman
2021-03-05 12:22 ` [PATCH 4.9 18/41] JFS: more checks for invalid superblock Greg Kroah-Hartman
2021-03-05 12:22 ` [PATCH 4.9 19/41] xfs: Fix assert failure in xfs_setattr_size() Greg Kroah-Hartman
2021-03-05 12:22 ` [PATCH 4.9 20/41] smackfs: restrict bytes count in smackfs write functions Greg Kroah-Hartman
2021-03-05 12:22 ` [PATCH 4.9 21/41] net: fix up truesize of cloned skb in skb_prepare_for_shift() Greg Kroah-Hartman
2021-03-05 12:22 ` [PATCH 4.9 22/41] mm/hugetlb.c: fix unnecessary address expansion of pmd sharing Greg Kroah-Hartman
2021-03-05 12:22 ` [PATCH 4.9 23/41] staging: fwserial: Fix error handling in fwserial_create Greg Kroah-Hartman
2021-03-05 12:22 ` [PATCH 4.9 24/41] x86/reboot: Add Zotac ZBOX CI327 nano PCI reboot quirk Greg Kroah-Hartman
2021-03-05 12:22 ` [PATCH 4.9 25/41] vt/consolemap: do font sum unsigned Greg Kroah-Hartman
2021-03-05 12:22 ` [PATCH 4.9 26/41] wlcore: Fix command execute failure 19 for wl12xx Greg Kroah-Hartman
2021-03-05 12:22 ` [PATCH 4.9 27/41] pktgen: fix misuse of BUG_ON() in pktgen_thread_worker() Greg Kroah-Hartman
2021-03-05 12:22 ` [PATCH 4.9 28/41] ath10k: fix wmi mgmt tx queue full due to race condition Greg Kroah-Hartman
2021-03-05 12:22 ` [PATCH 4.9 29/41] x86/build: Treat R_386_PLT32 relocation as R_386_PC32 Greg Kroah-Hartman
2021-03-05 12:22 ` [PATCH 4.9 30/41] Bluetooth: Fix null pointer dereference in amp_read_loc_assoc_final_data Greg Kroah-Hartman
2021-03-05 12:22 ` [PATCH 4.9 31/41] staging: most: sound: add sanity check for function argument Greg Kroah-Hartman
2021-03-05 12:22 ` [PATCH 4.9 32/41] media: uvcvideo: Allow entities with no pads Greg Kroah-Hartman
2021-03-05 12:22 ` [PATCH 4.9 33/41] scsi: iscsi: Restrict sessions and handles to admin capabilities Greg Kroah-Hartman
2021-03-05 12:22 ` [PATCH 4.9 34/41] sysfs: Add sysfs_emit and sysfs_emit_at to format sysfs output Greg Kroah-Hartman
2021-03-05 12:22 ` [PATCH 4.9 35/41] scsi: iscsi: Ensure sysfs attributes are limited to PAGE_SIZE Greg Kroah-Hartman
2021-03-05 12:22 ` [PATCH 4.9 36/41] scsi: iscsi: Verify lengths on passthrough PDUs Greg Kroah-Hartman
2021-03-05 12:22 ` [PATCH 4.9 37/41] Xen/gnttab: handle p2m update errors on a per-slot basis Greg Kroah-Hartman
2021-03-05 12:22 ` [PATCH 4.9 38/41] xen-netback: respect gnttab_map_refs()s return value Greg Kroah-Hartman
2021-03-05 12:22 ` [PATCH 4.9 39/41] zsmalloc: account the number of compacted pages correctly Greg Kroah-Hartman
2021-03-05 12:22 ` [PATCH 4.9 40/41] swap: fix swapfile read/write offset Greg Kroah-Hartman
2021-03-05 12:22 ` [PATCH 4.9 41/41] media: v4l: ioctl: Fix memory leak in video_usercopy Greg Kroah-Hartman
2021-03-06 5:16 ` [PATCH 4.9 00/41] 4.9.260-rc1 review Florian Fainelli
2021-03-06 16:29 ` Guenter Roeck
2021-03-06 16:30 ` Guenter Roeck
2021-03-07 2:26 ` Naresh Kamboju
2021-03-12 20:24 ` Florian Fainelli
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20210305120851.538190367@linuxfoundation.org \
--to=gregkh@linuxfoundation.org \
--cc=ben@decadent.org.uk \
--cc=dvhart@infradead.org \
--cc=gratian.crisan@ni.com \
--cc=linux-kernel@vger.kernel.org \
--cc=peterz@infradead.org \
--cc=stable@vger.kernel.org \
--cc=tglx@linutronix.de \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).