From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Juergen Gross <jgross@suse.com>, Jan Beulich <jbeulich@suse.com>
Subject: [PATCH 4.4 50/64] xen/events: fix race in evtchn_fifo_unmask()
Date: Tue, 17 Nov 2020 14:05:13 +0100 [thread overview]
Message-ID: <20201117122108.636669729@linuxfoundation.org> (raw)
In-Reply-To: <20201117122106.144800239@linuxfoundation.org>
From: Juergen Gross <jgross@suse.com>
commit f01337197419b7e8a492e83089552b77d3b5fb90 upstream.
Unmasking a fifo event channel can result in unmasking it twice, once
directly in the kernel and once via a hypercall in case the event was
pending.
Fix that by doing the local unmask only if the event is not pending.
This is part of XSA-332.
Cc: stable@vger.kernel.org
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/xen/events/events_fifo.c | 13 +++++++++----
1 file changed, 9 insertions(+), 4 deletions(-)
--- a/drivers/xen/events/events_fifo.c
+++ b/drivers/xen/events/events_fifo.c
@@ -227,19 +227,25 @@ static bool evtchn_fifo_is_masked(unsign
return sync_test_bit(EVTCHN_FIFO_BIT(MASKED, word), BM(word));
}
/*
- * Clear MASKED, spinning if BUSY is set.
+ * Clear MASKED if not PENDING, spinning if BUSY is set.
+ * Return true if mask was cleared.
*/
-static void clear_masked(volatile event_word_t *word)
+static bool clear_masked_cond(volatile event_word_t *word)
{
event_word_t new, old, w;
w = *word;
do {
+ if (w & (1 << EVTCHN_FIFO_PENDING))
+ return false;
+
old = w & ~(1 << EVTCHN_FIFO_BUSY);
new = old & ~(1 << EVTCHN_FIFO_MASKED);
w = sync_cmpxchg(word, old, new);
} while (w != old);
+
+ return true;
}
static void evtchn_fifo_unmask(unsigned port)
@@ -248,8 +254,7 @@ static void evtchn_fifo_unmask(unsigned
BUG_ON(!irqs_disabled());
- clear_masked(word);
- if (evtchn_fifo_is_pending(port)) {
+ if (!clear_masked_cond(word)) {
struct evtchn_unmask unmask = { .port = port };
(void)HYPERVISOR_event_channel_op(EVTCHNOP_unmask, &unmask);
}
next prev parent reply other threads:[~2020-11-17 13:08 UTC|newest]
Thread overview: 68+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-17 13:04 [PATCH 4.4 00/64] 4.4.244-rc1 review Greg Kroah-Hartman
2020-11-17 13:04 ` [PATCH 4.4 01/64] ring-buffer: Fix recursion protection transitions between interrupt context Greg Kroah-Hartman
2020-11-17 13:04 ` [PATCH 4.4 02/64] gfs2: Wake up when sd_glock_disposal becomes zero Greg Kroah-Hartman
2020-11-17 13:04 ` [PATCH 4.4 03/64] mm: mempolicy: fix potential pte_unmap_unlock pte error Greg Kroah-Hartman
2020-11-17 13:04 ` [PATCH 4.4 04/64] time: Prevent undefined behaviour in timespec64_to_ns() Greg Kroah-Hartman
2020-11-17 13:04 ` [PATCH 4.4 05/64] btrfs: reschedule when cloning lots of extents Greg Kroah-Hartman
2020-11-17 13:04 ` [PATCH 4.4 06/64] net: xfrm: fix a race condition during allocing spi Greg Kroah-Hartman
2020-11-17 13:04 ` [PATCH 4.4 07/64] perf tools: Add missing swap for ino_generation Greg Kroah-Hartman
2020-11-17 13:04 ` [PATCH 4.4 08/64] ALSA: hda: prevent undefined shift in snd_hdac_ext_bus_get_link() Greg Kroah-Hartman
2020-11-17 13:04 ` [PATCH 4.4 09/64] can: dev: can_get_echo_skb(): prevent call to kfree_skb() in hard IRQ context Greg Kroah-Hartman
2020-11-17 13:04 ` [PATCH 4.4 10/64] can: dev: __can_get_echo_skb(): fix real payload length return value for RTR frames Greg Kroah-Hartman
2020-11-17 13:04 ` [PATCH 4.4 11/64] can: can_create_echo_skb(): fix echo skb generation: always use skb_clone() Greg Kroah-Hartman
2020-11-17 13:04 ` [PATCH 4.4 12/64] can: peak_usb: add range checking in decode operations Greg Kroah-Hartman
2020-11-17 13:04 ` [PATCH 4.4 13/64] can: peak_usb: peak_usb_get_ts_time(): fix timestamp wrapping Greg Kroah-Hartman
2020-11-17 13:04 ` [PATCH 4.4 14/64] Btrfs: fix missing error return if writeback for extent buffer never started Greg Kroah-Hartman
2020-11-17 13:04 ` [PATCH 4.4 15/64] pinctrl: devicetree: Avoid taking direct reference to device name string Greg Kroah-Hartman
2020-11-17 13:04 ` [PATCH 4.4 16/64] i40e: Wrong truncation from u16 to u8 Greg Kroah-Hartman
2020-11-17 13:04 ` [PATCH 4.4 17/64] i40e: Fix of memory leak and integer truncation in i40e_virtchnl.c Greg Kroah-Hartman
2020-11-17 13:04 ` [PATCH 4.4 18/64] geneve: add transport ports in route lookup for geneve Greg Kroah-Hartman
2020-11-17 13:04 ` [PATCH 4.4 19/64] ath9k_htc: Use appropriate rs_datalen type Greg Kroah-Hartman
2020-11-17 13:04 ` [PATCH 4.4 20/64] usb: gadget: goku_udc: fix potential crashes in probe Greg Kroah-Hartman
2020-11-17 13:04 ` [PATCH 4.4 21/64] gfs2: Free rd_bits later in gfs2_clear_rgrpd to fix use-after-free Greg Kroah-Hartman
2020-11-17 13:04 ` [PATCH 4.4 22/64] gfs2: check for live vs. read-only file system in gfs2_fitrim Greg Kroah-Hartman
2020-11-17 13:04 ` [PATCH 4.4 23/64] drm/amdgpu: perform srbm soft reset always on SDMA resume Greg Kroah-Hartman
2020-11-17 13:04 ` [PATCH 4.4 24/64] mac80211: fix use of skb payload instead of header Greg Kroah-Hartman
2020-11-17 13:04 ` [PATCH 4.4 25/64] mac80211: always wind down STA state Greg Kroah-Hartman
2020-11-17 13:04 ` [PATCH 4.4 26/64] cfg80211: regulatory: Fix inconsistent format argument Greg Kroah-Hartman
2020-11-17 13:04 ` [PATCH 4.4 27/64] iommu/amd: Increase interrupt remapping table limit to 512 entries Greg Kroah-Hartman
2020-11-17 13:04 ` [PATCH 4.4 28/64] xfs: fix a missing unlock on error in xfs_fs_map_blocks Greg Kroah-Hartman
2020-11-17 13:04 ` [PATCH 4.4 29/64] of/address: Fix of_node memory leak in of_dma_is_coherent Greg Kroah-Hartman
2020-11-17 13:04 ` [PATCH 4.4 30/64] cosa: Add missing kfree in error path of cosa_write Greg Kroah-Hartman
2020-11-17 13:04 ` [PATCH 4.4 31/64] perf: Fix get_recursion_context() Greg Kroah-Hartman
2020-11-17 13:04 ` [PATCH 4.4 32/64] ext4: correctly report "not supported" for {usr,grp}jquota when !CONFIG_QUOTA Greg Kroah-Hartman
2020-11-17 13:04 ` [PATCH 4.4 33/64] ext4: unlock xattr_sem properly in ext4_inline_data_truncate() Greg Kroah-Hartman
2020-11-17 13:04 ` [PATCH 4.4 34/64] usb: cdc-acm: Add DISABLE_ECHO for Renesas USB Download mode Greg Kroah-Hartman
2020-11-17 13:04 ` [PATCH 4.4 35/64] mei: protect mei_cl_mtu from null dereference Greg Kroah-Hartman
2020-11-17 13:04 ` [PATCH 4.4 36/64] ocfs2: initialize ip_next_orphan Greg Kroah-Hartman
2020-11-17 13:05 ` [PATCH 4.4 37/64] dont dump the threads that had been already exiting when zapped Greg Kroah-Hartman
2020-11-17 13:05 ` [PATCH 4.4 38/64] drm/gma500: Fix out-of-bounds access to struct drm_device.vblank[] Greg Kroah-Hartman
2020-11-17 13:05 ` [PATCH 4.4 39/64] pinctrl: amd: use higher precision for 512 RtcClk Greg Kroah-Hartman
2020-11-17 13:05 ` [PATCH 4.4 40/64] pinctrl: amd: fix incorrect way to disable debounce filter Greg Kroah-Hartman
2020-11-17 13:05 ` [PATCH 4.4 41/64] swiotlb: fix "x86: Dont panic if can not alloc buffer for swiotlb" Greg Kroah-Hartman
2020-11-17 13:05 ` [PATCH 4.4 42/64] IPv6: Set SIT tunnel hard_header_len to zero Greg Kroah-Hartman
2020-11-17 13:05 ` [PATCH 4.4 43/64] net/af_iucv: fix null pointer dereference on shutdown Greg Kroah-Hartman
2020-11-17 13:05 ` [PATCH 4.4 44/64] net/x25: Fix null-ptr-deref in x25_connect Greg Kroah-Hartman
2020-11-17 13:05 ` [PATCH 4.4 45/64] net: Update window_clamp if SOCK_RCVBUF is set Greg Kroah-Hartman
2020-11-17 13:05 ` [PATCH 4.4 46/64] random32: make prandom_u32() output unpredictable Greg Kroah-Hartman
2020-11-17 13:05 ` [PATCH 4.4 47/64] x86/speculation: Allow IBPB to be conditionally enabled on CPUs with always-on STIBP Greg Kroah-Hartman
2020-11-17 13:05 ` [PATCH 4.4 48/64] xen/events: avoid removing an event channel while handling it Greg Kroah-Hartman
2020-11-17 13:05 ` [PATCH 4.4 49/64] xen/events: add a proper barrier to 2-level uevent unmasking Greg Kroah-Hartman
2020-11-17 13:05 ` Greg Kroah-Hartman [this message]
2020-11-17 13:05 ` [PATCH 4.4 51/64] xen/events: add a new "late EOI" evtchn framework Greg Kroah-Hartman
2020-11-17 13:05 ` [PATCH 4.4 52/64] xen/blkback: use lateeoi irq binding Greg Kroah-Hartman
2020-11-17 13:05 ` [PATCH 4.4 53/64] xen/netback: " Greg Kroah-Hartman
2020-11-17 13:05 ` [PATCH 4.4 54/64] xen/scsiback: " Greg Kroah-Hartman
2020-11-17 13:05 ` [PATCH 4.4 55/64] xen/pciback: " Greg Kroah-Hartman
2020-11-17 13:05 ` [PATCH 4.4 56/64] xen/events: switch user event channels to lateeoi model Greg Kroah-Hartman
2020-11-17 13:05 ` [PATCH 4.4 57/64] xen/events: use a common cpu hotplug hook for event channels Greg Kroah-Hartman
2020-11-17 13:05 ` [PATCH 4.4 58/64] xen/events: defer eoi in case of excessive number of events Greg Kroah-Hartman
2020-11-17 13:05 ` [PATCH 4.4 59/64] xen/events: block rogue events for some time Greg Kroah-Hartman
2020-11-17 13:05 ` [PATCH 4.4 60/64] perf/core: Fix race in the perf_mmap_close() function Greg Kroah-Hartman
2020-11-17 13:05 ` [PATCH 4.4 61/64] Revert "kernel/reboot.c: convert simple_strtoul to kstrtoint" Greg Kroah-Hartman
2020-11-17 13:05 ` [PATCH 4.4 62/64] reboot: fix overflow parsing reboot cpu number Greg Kroah-Hartman
2020-11-17 13:05 ` [PATCH 4.4 63/64] ext4: fix leaking sysfs kobject after failed mount Greg Kroah-Hartman
2020-11-17 13:05 ` [PATCH 4.4 64/64] Convert trailing spaces and periods in path components Greg Kroah-Hartman
2020-11-17 18:27 ` [PATCH 4.4 00/64] 4.4.244-rc1 review Pavel Machek
2020-11-18 11:25 ` Naresh Kamboju
2020-11-18 15:22 ` Guenter Roeck
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