hw/usb/hcd-ohci.c in QEMU 5.0.0 has a stack-based buffer over-read via values obtained from the host controller driver.

QEMU 5.0.0 has a heap-based Buffer Overflow in flatview_read_continue in exec.c because hw/sd/sdhci.c mishandles a write operation in the SDHC_BLKSIZE case.

A TOCTOU mismatch in the NFS client code in the Linux kernel before 5.8.3 could be used by local attackers to corrupt memory or possibly have unspecified other impact because a size check is in fs/nfs/nfs4proc.c instead of fs/nfs/nfs4xdr.c, aka CID-b4487b935452.

Flatpak before 1.0.7, and 1.1.x and 1.2.x before 1.2.3, exposes /proc in the apply_extra script sandbox, which allows attackers to modify a host-side executable file.

Insufficient data validation in developer tools in Google Chrome on OS X prior to 74.0.3729.108 allowed a local attacker to execute arbitrary code via a crafted string copied to clipboard.

A code execution vulnerability exists in the directory rehashing functionality of E2fsprogs e2fsck 1.45.4. A specially crafted ext4 directory can cause an out-of-bounds write on the stack, resulting in code execution. An attacker can corrupt a partition to trigger this vulnerability.

In systemd before v242-rc4, it was discovered that pam_systemd does not properly sanitize the environment before using the XDG_SEAT variable. It is possible for an attacker, in some particular configurations, to set a XDG_SEAT environment variable which allows for commands to be checked against polkit policies using the "allow_active" element rather than "allow_any".

An issue was discovered in USBGuard before 1.1.0. On systems with the usbguard-dbus daemon running, an unprivileged user could make USBGuard allow all USB devices to be connected in the future.

runc through 1.0.0-rc9 has Incorrect Access Control leading to Escalation of Privileges, related to libcontainer/rootfs_linux.go. To exploit this, an attacker must be able to spawn two containers with custom volume-mount configurations, and be able to run custom images. (This vulnerability does not affect Docker due to an implementation detail that happens to block the attack.)

The default configuration of the apache2 package in Debian GNU/Linux squeeze before 2.2.16-6+squeeze7, wheezy before 2.2.22-4, and sid before 2.2.22-4, when mod_php or mod_rivet is used, provides example scripts under the doc/ URI, which might allow local users to conduct cross-site scripting (XSS) attacks, gain privileges, or obtain sensitive information via vectors involving localhost HTTP requests to the Apache HTTP Server.

OpenSC before 0.20.0-rc1 has an out-of-bounds access of an ASN.1 Octet string in asn1_decode_entry in libopensc/asn1.c.

OpenSC before 0.20.0-rc1 has an out-of-bounds access of an ASN.1 Bitstring in decode_bit_string in libopensc/asn1.c.

An issue was discovered in the Linux kernel before 5.0.5. There is a use-after-free issue when hci_uart_register_dev() fails in hci_uart_set_proto() in drivers/bluetooth/hci_ldisc.c.

runc through 1.1.4 has Incorrect Access Control leading to Escalation of Privileges, related to libcontainer/rootfs_linux.go. To exploit this, an attacker must be able to spawn two containers with custom volume-mount configurations, and be able to run custom images. NOTE: this issue exists because of a CVE-2019-19921 regression.

arch/powerpc/mm/mmu_context_book3s64.c in the Linux kernel before 5.1.15 for powerpc has a bug where unrelated processes may be able to read/write to one another's virtual memory under certain conditions via an mmap above 512 TB. Only a subset of powerpc systems are affected.

hw/net/xgmac.c in the XGMAC Ethernet controller in QEMU before 07-20-2020 has a buffer overflow. This occurs during packet transmission and affects the highbank and midway emulated machines. A guest user or process could use this flaw to crash the QEMU process on the host, resulting in a denial of service or potential privileged code execution. This was fixed in commit 5519724a13664b43e225ca05351c60b4468e4555.

mm/mremap.c in the Linux kernel before 5.13.3 has a use-after-free via a stale TLB because an rmap lock is not held during a PUD move.

IOMMU: RMRR (VT-d) and unity map (AMD-Vi) handling issues T[his CNA information record relates to multiple CVEs; the text explains which aspects/vulnerabilities correspond to which CVE.] Certain PCI devices in a system might be assigned Reserved Memory Regions (specified via Reserved Memory Region Reporting, "RMRR") for Intel VT-d or Unity Mapping ranges for AMD-Vi. These are typically used for platform tasks such as legacy USB emulation. Since the precise purpose of these regions is unknown, once a device associated with such a region is active, the mappings of these regions need to remain continuouly accessible by the device. This requirement has been violated. Subsequent DMA or interrupts from the device may have unpredictable behaviour, ranging from IOMMU faults to memory corruption.

IOMMU: RMRR (VT-d) and unity map (AMD-Vi) handling issues T[his CNA information record relates to multiple CVEs; the text explains which aspects/vulnerabilities correspond to which CVE.] Certain PCI devices in a system might be assigned Reserved Memory Regions (specified via Reserved Memory Region Reporting, "RMRR") for Intel VT-d or Unity Mapping ranges for AMD-Vi. These are typically used for platform tasks such as legacy USB emulation. Since the precise purpose of these regions is unknown, once a device associated with such a region is active, the mappings of these regions need to remain continuouly accessible by the device. This requirement has been violated. Subsequent DMA or interrupts from the device may have unpredictable behaviour, ranging from IOMMU faults to memory corruption.

The fix for bug CVE-2020-9484 introduced a time of check, time of use vulnerability into Apache Tomcat 10.1.0-M1 to 10.1.0-M8, 10.0.0-M5 to 10.0.14, 9.0.35 to 9.0.56 and 8.5.55 to 8.5.73 that allowed a local attacker to perform actions with the privileges of the user that the Tomcat process is using. This issue is only exploitable when Tomcat is configured to persist sessions using the FileStore.

open-vm-tools contains a file descriptor hijack vulnerability in the vmware-user-suid-wrapper. A malicious actor with non-root privileges may be able to hijack the /dev/uinput file descriptor allowing them to simulate user inputs.

In emulation_proc_handler of armv8_deprecated.c, there is a possible way to corrupt memory due to a race condition. This could lead to local escalation of privilege with no additional execution privileges needed. User interaction is not needed for exploitation.Product: AndroidVersions: Android kernelAndroid ID: A-237540956References: Upstream kernel

A potentially exploitable crash in TransportSecurityInfo used for SSL can be triggered by data stored in the local cache in the user profile directory. This issue is only exploitable in combination with another vulnerability allowing an attacker to write data into the local cache or from locally installed malware. This issue also triggers a non-exploitable startup crash for users switching between the Nightly and Release versions of Firefox if the same profile is used. This vulnerability affects Thunderbird < 60.2.1, Firefox ESR < 60.2.1, and Firefox < 62.0.2.

procps-ng before version 3.3.15 is vulnerable to a local privilege escalation in top. If a user runs top with HOME unset in an attacker-controlled directory, the attacker could achieve privilege escalation by exploiting one of several vulnerabilities in the config_file() function.

A flaw was found in the way the dumpable flag setting was handled when certain SUID binaries executed its descendants. The prerequisite is a SUID binary that sets real UID equal to effective UID, and real GID equal to effective GID. The descendant will then have a dumpable value set to 1. As a result, if the descendant process crashes and core_pattern is set to a relative value, its core dump is stored in the current directory with uid:gid permissions. An unprivileged local user with eligible root SUID binary could use this flaw to place core dumps into root-owned directories, potentially resulting in escalation of privileges.

hso_free_net_device in drivers/net/usb/hso.c in the Linux kernel through 5.13.4 calls unregister_netdev without checking for the NETREG_REGISTERED state, leading to a use-after-free and a double free.

In the Linux kernel, the following vulnerability has been resolved: ALSA: sh: aica: reorder cleanup operations to avoid UAF bugs The dreamcastcard->timer could schedule the spu_dma_work and the spu_dma_work could also arm the dreamcastcard->timer. When the snd_pcm_substream is closing, the aica_channel will be deallocated. But it could still be dereferenced in the worker thread. The reason is that del_timer() will return directly regardless of whether the timer handler is running or not and the worker could be rescheduled in the timer handler. As a result, the UAF bug will happen. The racy situation is shown below: (Thread 1) | (Thread 2) snd_aicapcm_pcm_close() | ... | run_spu_dma() //worker | mod_timer() flush_work() | del_timer() | aica_period_elapsed() //timer kfree(dreamcastcard->channel) | schedule_work() | run_spu_dma() //worker ... | dreamcastcard->channel-> //USE In order to mitigate this bug and other possible corner cases, call mod_timer() conditionally in run_spu_dma(), then implement PCM sync_stop op to cancel both the timer and worker. The sync_stop op will be called from PCM core appropriately when needed.

The fix for CVE-2020-9484 was incomplete. When using Apache Tomcat 10.0.0-M1 to 10.0.0, 9.0.0.M1 to 9.0.41, 8.5.0 to 8.5.61 or 7.0.0. to 7.0.107 with a configuration edge case that was highly unlikely to be used, the Tomcat instance was still vulnerable to CVE-2020-9494. Note that both the previously published prerequisites for CVE-2020-9484 and the previously published mitigations for CVE-2020-9484 also apply to this issue.

The OPVPWrapper::loadDriver function in oprs/OPVPWrapper.cxx in the pdftoopvp filter in CUPS and cups-filters before 1.0.47 allows local users to gain privileges via a Trojan horse driver in the same directory as the PDF file.

grant table v2 status pages may remain accessible after de-allocation (take two) Guest get permitted access to certain Xen-owned pages of memory. The majority of such pages remain allocated / associated with a guest for its entire lifetime. Grant table v2 status pages, however, get de-allocated when a guest switched (back) from v2 to v1. The freeing of such pages requires that the hypervisor know where in the guest these pages were mapped. The hypervisor tracks only one use within guest space, but racing requests from the guest to insert mappings of these pages may result in any of them to become mapped in multiple locations. Upon switching back from v2 to v1, the guest would then retain access to a page that was freed and perhaps re-used for other purposes. This bug was fortuitously fixed by code cleanup in Xen 4.14, and backported to security-supported Xen branches as a prerequisite of the fix for XSA-378.

Race condition in the sandbox launcher implementation in Google Chrome before 11.0.696.57 on Linux allows remote attackers to cause a denial of service or possibly have unspecified other impact via unknown vectors.

In Paramiko before 2.10.1, a race condition (between creation and chmod) in the write_private_key_file function could allow unauthorized information disclosure.

In the Linux kernel before 4.9.3, fs/xfs/xfs_aops.c allows local users to cause a denial of service (system crash) because there is a race condition between direct and memory-mapped I/O (associated with a hole) that is handled with BUG_ON instead of an I/O failure.

In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_tables: flush pending destroy work before exit_net release Similar to 2c9f0293280e ("netfilter: nf_tables: flush pending destroy work before netlink notifier") to address a race between exit_net and the destroy workqueue. The trace below shows an element to be released via destroy workqueue while exit_net path (triggered via module removal) has already released the set that is used in such transaction. [ 1360.547789] BUG: KASAN: slab-use-after-free in nf_tables_trans_destroy_work+0x3f5/0x590 [nf_tables] [ 1360.547861] Read of size 8 at addr ffff888140500cc0 by task kworker/4:1/152465 [ 1360.547870] CPU: 4 PID: 152465 Comm: kworker/4:1 Not tainted 6.8.0+ #359 [ 1360.547882] Workqueue: events nf_tables_trans_destroy_work [nf_tables] [ 1360.547984] Call Trace: [ 1360.547991] <TASK> [ 1360.547998] dump_stack_lvl+0x53/0x70 [ 1360.548014] print_report+0xc4/0x610 [ 1360.548026] ? __virt_addr_valid+0xba/0x160 [ 1360.548040] ? __pfx__raw_spin_lock_irqsave+0x10/0x10 [ 1360.548054] ? nf_tables_trans_destroy_work+0x3f5/0x590 [nf_tables] [ 1360.548176] kasan_report+0xae/0xe0 [ 1360.548189] ? nf_tables_trans_destroy_work+0x3f5/0x590 [nf_tables] [ 1360.548312] nf_tables_trans_destroy_work+0x3f5/0x590 [nf_tables] [ 1360.548447] ? __pfx_nf_tables_trans_destroy_work+0x10/0x10 [nf_tables] [ 1360.548577] ? _raw_spin_unlock_irq+0x18/0x30 [ 1360.548591] process_one_work+0x2f1/0x670 [ 1360.548610] worker_thread+0x4d3/0x760 [ 1360.548627] ? __pfx_worker_thread+0x10/0x10 [ 1360.548640] kthread+0x16b/0x1b0 [ 1360.548653] ? __pfx_kthread+0x10/0x10 [ 1360.548665] ret_from_fork+0x2f/0x50 [ 1360.548679] ? __pfx_kthread+0x10/0x10 [ 1360.548690] ret_from_fork_asm+0x1a/0x30 [ 1360.548707] </TASK> [ 1360.548719] Allocated by task 192061: [ 1360.548726] kasan_save_stack+0x20/0x40 [ 1360.548739] kasan_save_track+0x14/0x30 [ 1360.548750] __kasan_kmalloc+0x8f/0xa0 [ 1360.548760] __kmalloc_node+0x1f1/0x450 [ 1360.548771] nf_tables_newset+0x10c7/0x1b50 [nf_tables] [ 1360.548883] nfnetlink_rcv_batch+0xbc4/0xdc0 [nfnetlink] [ 1360.548909] nfnetlink_rcv+0x1a8/0x1e0 [nfnetlink] [ 1360.548927] netlink_unicast+0x367/0x4f0 [ 1360.548935] netlink_sendmsg+0x34b/0x610 [ 1360.548944] ____sys_sendmsg+0x4d4/0x510 [ 1360.548953] ___sys_sendmsg+0xc9/0x120 [ 1360.548961] __sys_sendmsg+0xbe/0x140 [ 1360.548971] do_syscall_64+0x55/0x120 [ 1360.548982] entry_SYSCALL_64_after_hwframe+0x55/0x5d [ 1360.548994] Freed by task 192222: [ 1360.548999] kasan_save_stack+0x20/0x40 [ 1360.549009] kasan_save_track+0x14/0x30 [ 1360.549019] kasan_save_free_info+0x3b/0x60 [ 1360.549028] poison_slab_object+0x100/0x180 [ 1360.549036] __kasan_slab_free+0x14/0x30 [ 1360.549042] kfree+0xb6/0x260 [ 1360.549049] __nft_release_table+0x473/0x6a0 [nf_tables] [ 1360.549131] nf_tables_exit_net+0x170/0x240 [nf_tables] [ 1360.549221] ops_exit_list+0x50/0xa0 [ 1360.549229] free_exit_list+0x101/0x140 [ 1360.549236] unregister_pernet_operations+0x107/0x160 [ 1360.549245] unregister_pernet_subsys+0x1c/0x30 [ 1360.549254] nf_tables_module_exit+0x43/0x80 [nf_tables] [ 1360.549345] __do_sys_delete_module+0x253/0x370 [ 1360.549352] do_syscall_64+0x55/0x120 [ 1360.549360] entry_SYSCALL_64_after_hwframe+0x55/0x5d (gdb) list *__nft_release_table+0x473 0x1e033 is in __nft_release_table (net/netfilter/nf_tables_api.c:11354). 11349 list_for_each_entry_safe(flowtable, nf, &table->flowtables, list) { 11350 list_del(&flowtable->list); 11351 nft_use_dec(&table->use); 11352 nf_tables_flowtable_destroy(flowtable); 11353 } 11354 list_for_each_entry_safe(set, ns, &table->sets, list) { 11355 list_del(&set->list); 11356 nft_use_dec(&table->use); 11357 if (set->flags & (NFT_SET_MAP | NFT_SET_OBJECT)) 11358 nft_map_deactivat ---truncated---

In the Linux kernel, the following vulnerability has been resolved: netfilter: nf_tables: Fix potential data-race in __nft_flowtable_type_get() nft_unregister_flowtable_type() within nf_flow_inet_module_exit() can concurrent with __nft_flowtable_type_get() within nf_tables_newflowtable(). And thhere is not any protection when iterate over nf_tables_flowtables list in __nft_flowtable_type_get(). Therefore, there is pertential data-race of nf_tables_flowtables list entry. Use list_for_each_entry_rcu() to iterate over nf_tables_flowtables list in __nft_flowtable_type_get(), and use rcu_read_lock() in the caller nft_flowtable_type_get() to protect the entire type query process.

Race condition in the tty_fasync function in drivers/char/tty_io.c in the Linux kernel before 2.6.32.6 allows local users to cause a denial of service (NULL pointer dereference and system crash) or possibly have unspecified other impact via unknown vectors, related to the put_tty_queue and __f_setown functions. NOTE: the vulnerability was addressed in a different way in 2.6.32.9.

Race condition in the NPObjWrapper_NewResolve function in modules/plugin/base/src/nsJSNPRuntime.cpp in xul.dll in Mozilla Firefox 3 before 3.0.11 might allow remote attackers to execute arbitrary code via a page transition during Java applet loading, related to a use-after-free vulnerability for memory associated with a destroyed Java object.

A race condition flaw was found in Ansible Engine 2.7.17 and prior, 2.8.9 and prior, 2.9.6 and prior when running a playbook with an unprivileged become user. When Ansible needs to run a module with become user, the temporary directory is created in /var/tmp. This directory is created with "umask 77 && mkdir -p <dir>"; this operation does not fail if the directory already exists and is owned by another user. An attacker could take advantage to gain control of the become user as the target directory can be retrieved by iterating '/proc/<pid>/cmdline'.

Race condition in the SystemTap stap tool 0.0.20080705 and 0.0.20090314 allows local users in the stapusr group to insert arbitrary SystemTap kernel modules and gain privileges via unknown vectors.

Go before 1.13.13 and 1.14.x before 1.14.5 has a data race in some net/http servers, as demonstrated by the httputil.ReverseProxy Handler, because it reads a request body and writes a response at the same time.

nsFrameManager in Firefox 3.x before 3.0.4, Firefox 2.x before 2.0.0.18, Thunderbird 2.x before 2.0.0.18, and SeaMonkey 1.x before 1.1.13 allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code by modifying properties of a file input element while it is still being initialized, then using the blur method to access uninitialized memory.

Race condition in the grant table code in Xen 4.6.x through 4.9.x allows local guest OS administrators to cause a denial of service (free list corruption and host crash) or gain privileges on the host via vectors involving maptrack free list handling.

The shadow-paging feature in Xen through 4.8.x mismanages page references and consequently introduces a race condition, which allows guest OS users to obtain Xen privileges, aka XSA-219.

In the Linux kernel, the following vulnerability has been resolved: wifi: mac80211: fix race condition on enabling fast-xmit fast-xmit must only be enabled after the sta has been uploaded to the driver, otherwise it could end up passing the not-yet-uploaded sta via drv_tx calls to the driver, leading to potential crashes because of uninitialized drv_priv data. Add a missing sta->uploaded check and re-check fast xmit after inserting a sta.

drivers/video/fbdev/smscufx.c in the Linux kernel through 5.19.12 has a race condition and resultant use-after-free if a physically proximate attacker removes a USB device while calling open(), aka a race condition between ufx_ops_open and ufx_usb_disconnect.

roccat_report_event in drivers/hid/hid-roccat.c in the Linux kernel through 5.19.12 has a race condition and resultant use-after-free in certain situations where a report is received while copying a report->value is in progress.

In the Linux kernel, the following vulnerability has been resolved: hv_netvsc: Fix race condition between netvsc_probe and netvsc_remove In commit ac5047671758 ("hv_netvsc: Disable NAPI before closing the VMBus channel"), napi_disable was getting called for all channels, including all subchannels without confirming if they are enabled or not. This caused hv_netvsc getting hung at napi_disable, when netvsc_probe() has finished running but nvdev->subchan_work has not started yet. netvsc_subchan_work() -> rndis_set_subchannel() has not created the sub-channels and because of that netvsc_sc_open() is not running. netvsc_remove() calls cancel_work_sync(&nvdev->subchan_work), for which netvsc_subchan_work did not run. netif_napi_add() sets the bit NAPI_STATE_SCHED because it ensures NAPI cannot be scheduled. Then netvsc_sc_open() -> napi_enable will clear the NAPIF_STATE_SCHED bit, so it can be scheduled. napi_disable() does the opposite. Now during netvsc_device_remove(), when napi_disable is called for those subchannels, napi_disable gets stuck on infinite msleep. This fix addresses this problem by ensuring that napi_disable() is not getting called for non-enabled NAPI struct. But netif_napi_del() is still necessary for these non-enabled NAPI struct for cleanup purpose. Call trace: [ 654.559417] task:modprobe state:D stack: 0 pid: 2321 ppid: 1091 flags:0x00004002 [ 654.568030] Call Trace: [ 654.571221] <TASK> [ 654.573790] __schedule+0x2d6/0x960 [ 654.577733] schedule+0x69/0xf0 [ 654.581214] schedule_timeout+0x87/0x140 [ 654.585463] ? __bpf_trace_tick_stop+0x20/0x20 [ 654.590291] msleep+0x2d/0x40 [ 654.593625] napi_disable+0x2b/0x80 [ 654.597437] netvsc_device_remove+0x8a/0x1f0 [hv_netvsc] [ 654.603935] rndis_filter_device_remove+0x194/0x1c0 [hv_netvsc] [ 654.611101] ? do_wait_intr+0xb0/0xb0 [ 654.615753] netvsc_remove+0x7c/0x120 [hv_netvsc] [ 654.621675] vmbus_remove+0x27/0x40 [hv_vmbus]

In the Linux kernel, the following vulnerability has been resolved: wireguard: receive: annotate data-race around receiving_counter.counter Syzkaller with KCSAN identified a data-race issue when accessing keypair->receiving_counter.counter. Use READ_ONCE() and WRITE_ONCE() annotations to mark the data race as intentional. BUG: KCSAN: data-race in wg_packet_decrypt_worker / wg_packet_rx_poll write to 0xffff888107765888 of 8 bytes by interrupt on cpu 0: counter_validate drivers/net/wireguard/receive.c:321 [inline] wg_packet_rx_poll+0x3ac/0xf00 drivers/net/wireguard/receive.c:461 __napi_poll+0x60/0x3b0 net/core/dev.c:6536 napi_poll net/core/dev.c:6605 [inline] net_rx_action+0x32b/0x750 net/core/dev.c:6738 __do_softirq+0xc4/0x279 kernel/softirq.c:553 do_softirq+0x5e/0x90 kernel/softirq.c:454 __local_bh_enable_ip+0x64/0x70 kernel/softirq.c:381 __raw_spin_unlock_bh include/linux/spinlock_api_smp.h:167 [inline] _raw_spin_unlock_bh+0x36/0x40 kernel/locking/spinlock.c:210 spin_unlock_bh include/linux/spinlock.h:396 [inline] ptr_ring_consume_bh include/linux/ptr_ring.h:367 [inline] wg_packet_decrypt_worker+0x6c5/0x700 drivers/net/wireguard/receive.c:499 process_one_work kernel/workqueue.c:2633 [inline] ... read to 0xffff888107765888 of 8 bytes by task 3196 on cpu 1: decrypt_packet drivers/net/wireguard/receive.c:252 [inline] wg_packet_decrypt_worker+0x220/0x700 drivers/net/wireguard/receive.c:501 process_one_work kernel/workqueue.c:2633 [inline] process_scheduled_works+0x5b8/0xa30 kernel/workqueue.c:2706 worker_thread+0x525/0x730 kernel/workqueue.c:2787 ...

In the Linux kernel, the following vulnerability has been resolved: mm: swap: fix race between free_swap_and_cache() and swapoff() There was previously a theoretical window where swapoff() could run and teardown a swap_info_struct while a call to free_swap_and_cache() was running in another thread. This could cause, amongst other bad possibilities, swap_page_trans_huge_swapped() (called by free_swap_and_cache()) to access the freed memory for swap_map. This is a theoretical problem and I haven't been able to provoke it from a test case. But there has been agreement based on code review that this is possible (see link below). Fix it by using get_swap_device()/put_swap_device(), which will stall swapoff(). There was an extra check in _swap_info_get() to confirm that the swap entry was not free. This isn't present in get_swap_device() because it doesn't make sense in general due to the race between getting the reference and swapoff. So I've added an equivalent check directly in free_swap_and_cache(). Details of how to provoke one possible issue (thanks to David Hildenbrand for deriving this): --8<----- __swap_entry_free() might be the last user and result in "count == SWAP_HAS_CACHE". swapoff->try_to_unuse() will stop as soon as soon as si->inuse_pages==0. So the question is: could someone reclaim the folio and turn si->inuse_pages==0, before we completed swap_page_trans_huge_swapped(). Imagine the following: 2 MiB folio in the swapcache. Only 2 subpages are still references by swap entries. Process 1 still references subpage 0 via swap entry. Process 2 still references subpage 1 via swap entry. Process 1 quits. Calls free_swap_and_cache(). -> count == SWAP_HAS_CACHE [then, preempted in the hypervisor etc.] Process 2 quits. Calls free_swap_and_cache(). -> count == SWAP_HAS_CACHE Process 2 goes ahead, passes swap_page_trans_huge_swapped(), and calls __try_to_reclaim_swap(). __try_to_reclaim_swap()->folio_free_swap()->delete_from_swap_cache()-> put_swap_folio()->free_swap_slot()->swapcache_free_entries()-> swap_entry_free()->swap_range_free()-> ... WRITE_ONCE(si->inuse_pages, si->inuse_pages - nr_entries); What stops swapoff to succeed after process 2 reclaimed the swap cache but before process1 finished its call to swap_page_trans_huge_swapped()? --8<-----

In the Linux kernel, the following vulnerability has been resolved: quota: Fix potential NULL pointer dereference Below race may cause NULL pointer dereference P1 P2 dquot_free_inode quota_off drop_dquot_ref remove_dquot_ref dquots = i_dquot(inode) dquots = i_dquot(inode) srcu_read_lock dquots[cnt]) != NULL (1) dquots[type] = NULL (2) spin_lock(&dquots[cnt]->dq_dqb_lock) (3) .... If dquot_free_inode(or other routines) checks inode's quota pointers (1) before quota_off sets it to NULL(2) and use it (3) after that, NULL pointer dereference will be triggered. So let's fix it by using a temporary pointer to avoid this issue.