← Back
CWE-362

2,963 CVEs • Abstraction: Class • Likelihood of Exploit: Medium

Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

The product contains a code sequence that can run concurrently with other code, and the code sequence requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence that is operating concurrently.

JSON object

Loading...

CVEs (2,963)

CVE
VENDORS
PRODUCTS
UPDATED
PUBLISHED
CVSS
1Linux
1Linux Kernel
Aug 4, 2026
Dec 2, 2024
N/A· v4
5.5 MEDIUM· v3
N/A· v2
In the Linux kernel, the following vulnerability has been resolved: net/mlx5: fs, lock FTE when checking if active The referenced commits introduced a two-step process for deleting FTEs: - Lock the FTE, delete it from...Show more
In the Linux kernel, the following vulnerability has been resolved: net/mlx5: fs, lock FTE when checking if active The referenced commits introduced a two-step process for deleting FTEs: - Lock the FTE, delete it from hardware, set the hardware deletion function to NULL and unlock the FTE. - Lock the parent flow group, delete the software copy of the FTE, and remove it from the xarray. However, this approach encounters a race condition if a rule with the same match value is added simultaneously. In this scenario, fs_core may set the hardware deletion function to NULL prematurely, causing a panic during subsequent rule deletions. To prevent this, ensure the active flag of the FTE is checked under a lock, which will prevent the fs_core layer from attaching a new steering rule to an FTE that is in the process of deletion. [ 438.967589] MOSHE: 2496 mlx5_del_flow_rules del_hw_func [ 438.968205] ------------[ cut here ]------------ [ 438.968654] refcount_t: decrement hit 0; leaking memory. [ 438.969249] WARNING: CPU: 0 PID: 8957 at lib/refcount.c:31 refcount_warn_saturate+0xfb/0x110 [ 438.970054] Modules linked in: act_mirred cls_flower act_gact sch_ingress openvswitch nsh mlx5_vdpa vringh vhost_iotlb vdpa mlx5_ib mlx5_core xt_conntrack xt_MASQUERADE nf_conntrack_netlink nfnetlink xt_addrtype iptable_nat nf_nat br_netfilter rpcsec_gss_krb5 auth_rpcgss oid_registry overlay rpcrdma rdma_ucm ib_iser libiscsi scsi_transport_iscsi ib_umad rdma_cm ib_ipoib iw_cm ib_cm ib_uverbs ib_core zram zsmalloc fuse [last unloaded: cls_flower] [ 438.973288] CPU: 0 UID: 0 PID: 8957 Comm: tc Not tainted 6.12.0-rc1+ #8 [ 438.973888] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.13.0-0-gf21b5a4aeb02-prebuilt.qemu.org 04/01/2014 [ 438.974874] RIP: 0010:refcount_warn_saturate+0xfb/0x110 [ 438.975363] Code: 40 66 3b 82 c6 05 16 e9 4d 01 01 e8 1f 7c a0 ff 0f 0b c3 cc cc cc cc 48 c7 c7 10 66 3b 82 c6 05 fd e8 4d 01 01 e8 05 7c a0 ff <0f> 0b c3 cc cc cc cc 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 00 90 [ 438.976947] RSP: 0018:ffff888124a53610 EFLAGS: 00010286 [ 438.977446] RAX: 0000000000000000 RBX: ffff888119d56de0 RCX: 0000000000000000 [ 438.978090] RDX: ffff88852c828700 RSI: ffff88852c81b3c0 RDI: ffff88852c81b3c0 [ 438.978721] RBP: ffff888120fa0e88 R08: 0000000000000000 R09: ffff888124a534b0 [ 438.979353] R10: 0000000000000001 R11: 0000000000000001 R12: ffff888119d56de0 [ 438.979979] R13: ffff888120fa0ec0 R14: ffff888120fa0ee8 R15: ffff888119d56de0 [ 438.980607] FS: 00007fe6dcc0f800(0000) GS:ffff88852c800000(0000) knlGS:0000000000000000 [ 438.983984] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 438.984544] CR2: 00000000004275e0 CR3: 0000000186982001 CR4: 0000000000372eb0 [ 438.985205] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 438.985842] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 438.986507] Call Trace: [ 438.986799] <TASK> [ 438.987070] ? __warn+0x7d/0x110 [ 438.987426] ? refcount_warn_saturate+0xfb/0x110 [ 438.987877] ? report_bug+0x17d/0x190 [ 438.988261] ? prb_read_valid+0x17/0x20 [ 438.988659] ? handle_bug+0x53/0x90 [ 438.989054] ? exc_invalid_op+0x14/0x70 [ 438.989458] ? asm_exc_invalid_op+0x16/0x20 [ 438.989883] ? refcount_warn_saturate+0xfb/0x110 [ 438.990348] mlx5_del_flow_rules+0x2f7/0x340 [mlx5_core] [ 438.990932] __mlx5_eswitch_del_rule+0x49/0x170 [mlx5_core] [ 438.991519] ? mlx5_lag_is_sriov+0x3c/0x50 [mlx5_core] [ 438.992054] ? xas_load+0x9/0xb0 [ 438.992407] mlx5e_tc_rule_unoffload+0x45/0xe0 [mlx5_core] [ 438.993037] mlx5e_tc_del_fdb_flow+0x2a6/0x2e0 [mlx5_core] [ 438.993623] mlx5e_flow_put+0x29/0x60 [mlx5_core] [ 438.994161] mlx5e_delete_flower+0x261/0x390 [mlx5_core] [ 438.994728] tc_setup_cb_destroy+0xb9/0x190 [ 438.995150] fl_hw_destroy_filter+0x94/0xc0 [cls_flower] [ 438.995650] fl_change+0x11a4/0x13c0 [cls_flower] [ 438.996105] tc_new_tfilter+0x347/0xbc0 [ 438.996503] ? __ ---truncated---Show less
1Ffmpeg
1Ffmpeg
Jun 17, 2026
Nov 29, 2024
N/A· v4
5.9 MEDIUM· v3
N/A· v2
FFmpeg n7.0 has a race condition vulnerability in the VP9 decoder. This could lead to a data race if video encoding parameters were being exported, as the side data would be attached in the decoder thread while being rea...Show more
FFmpeg n7.0 has a race condition vulnerability in the VP9 decoder. This could lead to a data race if video encoding parameters were being exported, as the side data would be attached in the decoder thread while being read in the output thread.Show less
1Mobyproject
1Moby
Jun 17, 2026
Nov 29, 2024
N/A· v4
8.1 HIGH· v3
N/A· v2
moby through v25.0.3 has a Race Condition vulnerability in the streamformatter package which can be used to trigger multiple concurrent write operations resulting in data corruption or application crashes.
1Mobyproject
1Moby
Jun 17, 2026
Nov 29, 2024
N/A· v4
6.5 MEDIUM· v3
N/A· v2
moby v25.0.5 is affected by a Race Condition in builder/builder-next/adapters/snapshot/layer.go. The vulnerability could be used to trigger concurrent builds that call the EnsureLayer function resulting in resource leaks...Show more
moby v25.0.5 is affected by a Race Condition in builder/builder-next/adapters/snapshot/layer.go. The vulnerability could be used to trigger concurrent builds that call the EnsureLayer function resulting in resource leaks/exhaustion.Show less
1Mozilla
2Firefox
Thunderbird
Jun 17, 2026
Nov 26, 2024
N/A· v4
6.5 MEDIUM· v3
N/A· v2
Missing thread synchronization primitives could have led to a data race on members of the PlaybackParams structure. This vulnerability affects Firefox < 133 and Thunderbird < 133.
1Ibm
1Watson Assistant For Ibm Cloud Pak For Data
Jun 17, 2026
Nov 26, 2024
N/A· v4
5.9 MEDIUM· v3
N/A· v2
IBM Watson Speech Services Cartridge for IBM Cloud Pak for Data 4.0.0 through 5.0.2 does not properly check inputs to resources that are used concurrently, which might lead to unexpected states, possibly resulting in a c...Show more
IBM Watson Speech Services Cartridge for IBM Cloud Pak for Data 4.0.0 through 5.0.2 does not properly check inputs to resources that are used concurrently, which might lead to unexpected states, possibly resulting in a crash.Show less
1Linux
1Linux Kernel
Aug 4, 2026
Nov 25, 2024
N/A· v4
4.7 MEDIUM· v3
N/A· v2
In the Linux kernel, the following vulnerability has been resolved: nvme: tcp: avoid race between queue_lock lock and destroy Commit 76d54bf20cdc ("nvme-tcp: don't access released socket during error recovery") added a...Show more
In the Linux kernel, the following vulnerability has been resolved: nvme: tcp: avoid race between queue_lock lock and destroy Commit 76d54bf20cdc ("nvme-tcp: don't access released socket during error recovery") added a mutex_lock() call for the queue->queue_lock in nvme_tcp_get_address(). However, the mutex_lock() races with mutex_destroy() in nvme_tcp_free_queue(), and causes the WARN below. DEBUG_LOCKS_WARN_ON(lock->magic != lock) WARNING: CPU: 3 PID: 34077 at kernel/locking/mutex.c:587 __mutex_lock+0xcf0/0x1220 Modules linked in: nvmet_tcp nvmet nvme_tcp nvme_fabrics iw_cm ib_cm ib_core pktcdvd nft_fib_inet nft_fib_ipv4 nft_fib_ipv6 nft_fib nft_reject_inet nf_reject_ipv4 nf_reject_ipv6 nft_reject nft_ct nft_chain_nat nf_nat nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 ip_set nf_tables qrtr sunrpc ppdev 9pnet_virtio 9pnet pcspkr netfs parport_pc parport e1000 i2c_piix4 i2c_smbus loop fuse nfnetlink zram bochs drm_vram_helper drm_ttm_helper ttm drm_kms_helper xfs drm sym53c8xx floppy nvme scsi_transport_spi nvme_core nvme_auth serio_raw ata_generic pata_acpi dm_multipath qemu_fw_cfg [last unloaded: ib_uverbs] CPU: 3 UID: 0 PID: 34077 Comm: udisksd Not tainted 6.11.0-rc7 #319 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-2.fc40 04/01/2014 RIP: 0010:__mutex_lock+0xcf0/0x1220 Code: 08 84 d2 0f 85 c8 04 00 00 8b 15 ef b6 c8 01 85 d2 0f 85 78 f4 ff ff 48 c7 c6 20 93 ee af 48 c7 c7 60 91 ee af e8 f0 a7 6d fd <0f> 0b e9 5e f4 ff ff 48 b8 00 00 00 00 00 fc ff df 4c 89 f2 48 c1 RSP: 0018:ffff88811305f760 EFLAGS: 00010286 RAX: 0000000000000000 RBX: ffff88812c652058 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 0000000000000004 RDI: 0000000000000001 RBP: ffff88811305f8b0 R08: 0000000000000001 R09: ffffed1075c36341 R10: ffff8883ae1b1a0b R11: 0000000000010498 R12: 0000000000000000 R13: 0000000000000000 R14: dffffc0000000000 R15: ffff88812c652058 FS: 00007f9713ae4980(0000) GS:ffff8883ae180000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fcd78483c7c CR3: 0000000122c38000 CR4: 00000000000006f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <TASK> ? __warn.cold+0x5b/0x1af ? __mutex_lock+0xcf0/0x1220 ? report_bug+0x1ec/0x390 ? handle_bug+0x3c/0x80 ? exc_invalid_op+0x13/0x40 ? asm_exc_invalid_op+0x16/0x20 ? __mutex_lock+0xcf0/0x1220 ? nvme_tcp_get_address+0xc2/0x1e0 [nvme_tcp] ? __pfx___mutex_lock+0x10/0x10 ? __lock_acquire+0xd6a/0x59e0 ? nvme_tcp_get_address+0xc2/0x1e0 [nvme_tcp] nvme_tcp_get_address+0xc2/0x1e0 [nvme_tcp] ? __pfx_nvme_tcp_get_address+0x10/0x10 [nvme_tcp] nvme_sysfs_show_address+0x81/0xc0 [nvme_core] dev_attr_show+0x42/0x80 ? __asan_memset+0x1f/0x40 sysfs_kf_seq_show+0x1f0/0x370 seq_read_iter+0x2cb/0x1130 ? rw_verify_area+0x3b1/0x590 ? __mutex_lock+0x433/0x1220 vfs_read+0x6a6/0xa20 ? lockdep_hardirqs_on+0x78/0x100 ? __pfx_vfs_read+0x10/0x10 ksys_read+0xf7/0x1d0 ? __pfx_ksys_read+0x10/0x10 ? __x64_sys_openat+0x105/0x1d0 do_syscall_64+0x93/0x180 ? lockdep_hardirqs_on_prepare+0x16d/0x400 ? do_syscall_64+0x9f/0x180 ? lockdep_hardirqs_on+0x78/0x100 ? do_syscall_64+0x9f/0x180 ? __pfx_ksys_read+0x10/0x10 ? lockdep_hardirqs_on_prepare+0x16d/0x400 ? do_syscall_64+0x9f/0x180 ? lockdep_hardirqs_on+0x78/0x100 ? do_syscall_64+0x9f/0x180 ? lockdep_hardirqs_on_prepare+0x16d/0x400 ? do_syscall_64+0x9f/0x180 ? lockdep_hardirqs_on+0x78/0x100 ? do_syscall_64+0x9f/0x180 ? lockdep_hardirqs_on_prepare+0x16d/0x400 ? do_syscall_64+0x9f/0x180 ? lockdep_hardirqs_on+0x78/0x100 ? do_syscall_64+0x9f/0x180 ? lockdep_hardirqs_on_prepare+0x16d/0x400 ? do_syscall_64+0x9f/0x180 ? lockdep_hardirqs_on+0x78/0x100 ? do_syscall_64+0x9f/0x180 ? do_syscall_64+0x9f/0x180 entry_SYSCALL_64_after_hwframe+0x76/0x7e RIP: 0033:0x7f9713f55cfa Code: 55 48 89 e5 48 83 ec 20 48 89 55 e8 48 89 75 f0 89 7d f8 e8 e8 74 f8 ff 48 8b 55 e8 48 8b 75 f0 4 ---truncated---Show less
1Linux
1Linux Kernel
Aug 4, 2026
Nov 19, 2024
N/A· v4
4.7 MEDIUM· v3
N/A· v2
In the Linux kernel, the following vulnerability has been resolved: i40e: fix race condition by adding filter's intermediate sync state Fix a race condition in the i40e driver that leads to MAC/VLAN filters becoming co...Show more
In the Linux kernel, the following vulnerability has been resolved: i40e: fix race condition by adding filter's intermediate sync state Fix a race condition in the i40e driver that leads to MAC/VLAN filters becoming corrupted and leaking. Address the issue that occurs under heavy load when multiple threads are concurrently modifying MAC/VLAN filters by setting mac and port VLAN. 1. Thread T0 allocates a filter in i40e_add_filter() within i40e_ndo_set_vf_port_vlan(). 2. Thread T1 concurrently frees the filter in __i40e_del_filter() within i40e_ndo_set_vf_mac(). 3. Subsequently, i40e_service_task() calls i40e_sync_vsi_filters(), which refers to the already freed filter memory, causing corruption. Reproduction steps: 1. Spawn multiple VFs. 2. Apply a concurrent heavy load by running parallel operations to change MAC addresses on the VFs and change port VLANs on the host. 3. Observe errors in dmesg: "Error I40E_AQ_RC_ENOSPC adding RX filters on VF XX, please set promiscuous on manually for VF XX". Exact code for stable reproduction Intel can't open-source now. The fix involves implementing a new intermediate filter state, I40E_FILTER_NEW_SYNC, for the time when a filter is on a tmp_add_list. These filters cannot be deleted from the hash list directly but must be removed using the full process.Show less
1Needrestart Project
1Needrestart
Jun 17, 2026
Nov 19, 2024
N/A· v4
7.8 HIGH· v3
N/A· v2
Qualys discovered that needrestart, before version 3.8, allows local attackers to execute arbitrary code as root by winning a race condition and tricking needrestart into running their own, fake Python interpreter (inste...Show more
Qualys discovered that needrestart, before version 3.8, allows local attackers to execute arbitrary code as root by winning a race condition and tricking needrestart into running their own, fake Python interpreter (instead of the system's real Python interpreter). The initial security fix (6ce6136) introduced a regression which was subsequently resolved (42af5d3).Show less
1Weaver
1E Cology
Jun 17, 2026
Nov 19, 2024
N/A· v4
9.8 CRITICAL· v3
N/A· v2
A vulnerability was found in Weaver E-cology allows attackers use race conditions to bypass security mechanisms to upload malicious files and control server privileges
1Linux
1Linux Kernel
Aug 4, 2026
Nov 19, 2024
N/A· v4
4.7 MEDIUM· v3
N/A· v2
In the Linux kernel, the following vulnerability has been resolved: net: xilinx: axienet: Enqueue Tx packets in dql before dmaengine starts Enqueue packets in dql after dma engine starts causes race condition. Tx trans...Show more
In the Linux kernel, the following vulnerability has been resolved: net: xilinx: axienet: Enqueue Tx packets in dql before dmaengine starts Enqueue packets in dql after dma engine starts causes race condition. Tx transfer starts once dma engine is started and may execute dql dequeue in completion before it gets queued. It results in following kernel crash while running iperf stress test: kernel BUG at lib/dynamic_queue_limits.c:99! <snip> Internal error: Oops - BUG: 00000000f2000800 [#1] SMP pc : dql_completed+0x238/0x248 lr : dql_completed+0x3c/0x248 Call trace: dql_completed+0x238/0x248 axienet_dma_tx_cb+0xa0/0x170 xilinx_dma_do_tasklet+0xdc/0x290 tasklet_action_common+0xf8/0x11c tasklet_action+0x30/0x3c handle_softirqs+0xf8/0x230 <snip> Start dmaengine after enqueue in dql fixes the crash.Show less
1Ivanti
1Secure Access Client
Jun 17, 2026
Nov 13, 2024
N/A· v4
4.7 MEDIUM· v3
N/A· v2
A race condition in Ivanti Secure Access Client before version 22.7R4 allows a local authenticated attacker to modify sensitive configuration files.
1Mendix
1Mendix
Jun 17, 2026
Nov 12, 2024
6.9 MEDIUM· v4
4.8 MEDIUM· v3
N/A· v2
A vulnerability has been identified in Mendix Runtime V10 (All versions < V10.16.0 only if the basic authentication mechanism is used by the application), Mendix Runtime V10.12 (All versions < V10.12.7 only if the basic...Show more
A vulnerability has been identified in Mendix Runtime V10 (All versions < V10.16.0 only if the basic authentication mechanism is used by the application), Mendix Runtime V10.12 (All versions < V10.12.7 only if the basic authentication mechanism is used by the application), Mendix Runtime V10.6 (All versions < V10.6.15 only if the basic authentication mechanism is used by the application), Mendix Runtime V8 (All versions only if the basic authentication mechanism is used by the application), Mendix Runtime V9 (All versions < V9.24.29 only if the basic authentication mechanism is used by the application). The basic authentication implementation of affected applications contains a race condition vulnerability which could allow unauthenticated remote attackers to circumvent default account lockout measures.Show less
1Linux
1Linux Kernel
Jun 17, 2026
Nov 8, 2024
N/A· v4
4.7 MEDIUM· v3
N/A· v2
In the Linux kernel, the following vulnerability has been resolved: scsi: lpfc: Ensure DA_ID handling completion before deleting an NPIV instance Deleting an NPIV instance requires all fabric ndlps to be released befor...Show more
In the Linux kernel, the following vulnerability has been resolved: scsi: lpfc: Ensure DA_ID handling completion before deleting an NPIV instance Deleting an NPIV instance requires all fabric ndlps to be released before an NPIV's resources can be torn down. Failure to release fabric ndlps beforehand opens kref imbalance race conditions. Fix by forcing the DA_ID to complete synchronously with usage of wait_queue.Show less
1Linux
1Linux Kernel
Aug 4, 2026
Nov 8, 2024
N/A· v4
4.7 MEDIUM· v3
N/A· v2
In the Linux kernel, the following vulnerability has been resolved: drm/panthor: Fix race when converting group handle to group object XArray provides it's own internal lock which protects the internal array when entri...Show more
In the Linux kernel, the following vulnerability has been resolved: drm/panthor: Fix race when converting group handle to group object XArray provides it's own internal lock which protects the internal array when entries are being simultaneously added and removed. However there is still a race between retrieving the pointer from the XArray and incrementing the reference count. To avoid this race simply hold the internal XArray lock when incrementing the reference count, this ensures there cannot be a racing call to xa_erase().Show less
1Linux
1Linux Kernel
Jun 17, 2026
Nov 5, 2024
N/A· v4
4.7 MEDIUM· v3
N/A· v2
In the Linux kernel, the following vulnerability has been resolved: nvme-pci: fix race condition between reset and nvme_dev_disable() nvme_dev_disable() modifies the dev->online_queues field, therefore nvme_pci_update_...Show more
In the Linux kernel, the following vulnerability has been resolved: nvme-pci: fix race condition between reset and nvme_dev_disable() nvme_dev_disable() modifies the dev->online_queues field, therefore nvme_pci_update_nr_queues() should avoid racing against it, otherwise we could end up passing invalid values to blk_mq_update_nr_hw_queues(). WARNING: CPU: 39 PID: 61303 at drivers/pci/msi/api.c:347 pci_irq_get_affinity+0x187/0x210 Workqueue: nvme-reset-wq nvme_reset_work [nvme] RIP: 0010:pci_irq_get_affinity+0x187/0x210 Call Trace: <TASK> ? blk_mq_pci_map_queues+0x87/0x3c0 ? pci_irq_get_affinity+0x187/0x210 blk_mq_pci_map_queues+0x87/0x3c0 nvme_pci_map_queues+0x189/0x460 [nvme] blk_mq_update_nr_hw_queues+0x2a/0x40 nvme_reset_work+0x1be/0x2a0 [nvme] Fix the bug by locking the shutdown_lock mutex before using dev->online_queues. Give up if nvme_dev_disable() is running or if it has been executed already.Show less
1Huawei
1Harmonyos
Jun 17, 2026
Nov 5, 2024
N/A· v4
4.7 MEDIUM· v3
N/A· v2
Race condition vulnerability in the kernel network module Impact:Successful exploitation of this vulnerability may affect availability.
1Mozilla
2Firefox
Thunderbird
Jun 17, 2026
Oct 29, 2024
N/A· v4
5.3 MEDIUM· v3
N/A· v2
Potential race conditions in IndexedDB could have caused memory corruption, leading to a potentially exploitable crash. This vulnerability affects Firefox < 132 and Thunderbird < 132.
2Argo Workflows Project
Argoproj
2Argo Workflows
Argo Workflows
Jun 17, 2026
Oct 28, 2024
N/A· v4
4.8 MEDIUM· v3
N/A· v2
Argo Workflows is an open source container-native workflow engine for orchestrating parallel jobs on Kubernetes. Due to a race condition in a global variable in 3.6.0-rc1, the argo workflows controller can be made to cra...Show more
Argo Workflows is an open source container-native workflow engine for orchestrating parallel jobs on Kubernetes. Due to a race condition in a global variable in 3.6.0-rc1, the argo workflows controller can be made to crash on-command by any user with access to execute a workflow. This vulnerability is fixed in 3.6.0-rc2.Show less
1Linux
1Linux Kernel
Aug 4, 2026
Oct 23, 2024
N/A· v4
7.0 HIGH· v3
N/A· v2
In the Linux kernel, the following vulnerability has been resolved: mm/mremap: fix move_normal_pmd/retract_page_tables race In mremap(), move_page_tables() looks at the type of the PMD entry and the specified address r...Show more
In the Linux kernel, the following vulnerability has been resolved: mm/mremap: fix move_normal_pmd/retract_page_tables race In mremap(), move_page_tables() looks at the type of the PMD entry and the specified address range to figure out by which method the next chunk of page table entries should be moved. At that point, the mmap_lock is held in write mode, but no rmap locks are held yet. For PMD entries that point to page tables and are fully covered by the source address range, move_pgt_entry(NORMAL_PMD, ...) is called, which first takes rmap locks, then does move_normal_pmd(). move_normal_pmd() takes the necessary page table locks at source and destination, then moves an entire page table from the source to the destination. The problem is: The rmap locks, which protect against concurrent page table removal by retract_page_tables() in the THP code, are only taken after the PMD entry has been read and it has been decided how to move it. So we can race as follows (with two processes that have mappings of the same tmpfs file that is stored on a tmpfs mount with huge=advise); note that process A accesses page tables through the MM while process B does it through the file rmap: process A process B ========= ========= mremap mremap_to move_vma move_page_tables get_old_pmd alloc_new_pmd *** PREEMPT *** madvise(MADV_COLLAPSE) do_madvise madvise_walk_vmas madvise_vma_behavior madvise_collapse hpage_collapse_scan_file collapse_file retract_page_tables i_mmap_lock_read(mapping) pmdp_collapse_flush i_mmap_unlock_read(mapping) move_pgt_entry(NORMAL_PMD, ...) take_rmap_locks move_normal_pmd drop_rmap_locks When this happens, move_normal_pmd() can end up creating bogus PMD entries in the line `pmd_populate(mm, new_pmd, pmd_pgtable(pmd))`. The effect depends on arch-specific and machine-specific details; on x86, you can end up with physical page 0 mapped as a page table, which is likely exploitable for user->kernel privilege escalation. Fix the race by letting process B recheck that the PMD still points to a page table after the rmap locks have been taken. Otherwise, we bail and let the caller fall back to the PTE-level copying path, which will then bail immediately at the pmd_none() check. Bug reachability: Reaching this bug requires that you can create shmem/file THP mappings - anonymous THP uses different code that doesn't zap stuff under rmap locks. File THP is gated on an experimental config flag (CONFIG_READ_ONLY_THP_FOR_FS), so on normal distro kernels you need shmem THP to hit this bug. As far as I know, getting shmem THP normally requires that you can mount your own tmpfs with the right mount flags, which would require creating your own user+mount namespace; though I don't know if some distros maybe enable shmem THP by default or something like that. Bug impact: This issue can likely be used for user->kernel privilege escalation when it is reachable.Show less