FKIE_CVE-2026-98431

Vulnerability from fkie_nvd - Published: 2026-10-14 14:17 - Updated: 2026-10-19 10:18
Severity
Summary
In the Linux kernel, the following vulnerability has been resolved: RDMA/uverbs: Fix mmap_lock/disassociation_lock circular dependency Commit 51976c6cd786 ("RDMA/core: Provide rdma_user_mmap_disassociate() to disassociate mmap pages") introduced disassociation_lock to protect new mmap registrations against uverbs_user_mmap_disassociate(), but created an ABBA deadlock: Thread A (mmap / fork): mmap_lock -> disassociation_lock Thread B (disassociate): disassociation_lock -> mmap_lock Fix by removing disassociation_lock entirely and using the pre-existing hw_destroy_rwsem instead. hw_destroy_rwsem already provides the same protection: rdma_umap_open() and ib_uverbs_mmap() both use down_read_trylock() before registering a new VMA, so holding hw_destroy_rwsem in uverbs_user_mmap_disassociate() is sufficient to block new registrations. trylock is used in both mmap paths (not blocking down_read) because mmap_lock is already held on entry, and uverbs_user_mmap_disassociate() acquires mmap_lock internally — a blocking read would recreate the same deadlock. The only caller that was not taking hw_destroy_rwsem for write was rdma_user_mmap_disassociate(). Fix it to take the rwsem per-ufile while iterating under lists_mutex. This is safe because ib_uverbs_close() releases hw_destroy_rwsem entirely before acquiring lists_mutex, so the two locks are never held simultaneously. lockdep warning: [ 776.654252] ====================================================== [ 776.655214] WARNING: possible circular locking dependency detected [ 776.656167] 6.18.0for-upstream_debug_94e244d9ccab #1 Not tainted [ 776.657114] ------------------------------------------------------ [ 776.658087] devlink/14824 is trying to acquire lock: [ 776.658879] ffff88811170c800 (&mm->mmap_lock){++++}-{4:4}, at: uverbs_user_mmap_disassociate+0x168/0x780 [ib_uverbs] [ 776.660479] [ 776.660479] but task is already holding lock: [ 776.661460] ffff888142d92b08 (&file->disassociation_lock){+.+.}-{4:4}, at: uverbs_user_mmap_disassociate+0x39/0x780 [ib_uverbs] [ 776.663177] [ 776.663177] which lock already depends on the new lock. [ 776.663177] [ 776.664525] [ 776.664525] the existing dependency chain (in reverse order) is: [ 776.665724] [ 776.665724] -> #2 (&file->disassociation_lock){+.+.}-{4:4}: [ 776.666887] __mutex_lock+0x16d/0x2330 [ 776.667633] rdma_umap_open+0x129/0x280 [ib_uverbs] [ 776.668489] dup_mmap+0xa40/0x1790 [ 776.669170] copy_process+0x5dd2/0x6170 [ 776.669933] kernel_clone+0xb6/0x610 [ 776.670636] __do_sys_clone+0xb5/0xf0 [ 776.671354] do_syscall_64+0x70/0x12e0 [ 776.672083] entry_SYSCALL_64_after_hwframe+0x4b/0x53 [ 776.672940] [ 776.672940] -> #1 (&mm->mmap_lock/1){+.+.}-{4:4}: [ 776.673985] down_write_nested+0x90/0x1e0 [ 776.674751] dup_mmap+0x201/0x1790 [ 776.675448] copy_process+0x5dd2/0x6170 [ 776.676180] kernel_clone+0xb6/0x610 [ 776.676904] __do_sys_clone+0xb5/0xf0 [ 776.677615] do_syscall_64+0x70/0x12e0 [ 776.678351] entry_SYSCALL_64_after_hwframe+0x4b/0x53 [ 776.679239] [ 776.679239] -> #0 (&mm->mmap_lock){++++}-{4:4}: [ 776.680253] __lock_acquire+0x18c6/0x2ec0 [ 776.681018] lock_acquire+0x10e/0x2e0 [ 776.681742] down_read+0x95/0x430 [ 776.682395] uverbs_user_mmap_disassociate+0x168/0x780 [ib_uverbs] [ 776.683436] uverbs_destroy_ufile_hw+0x1ae/0x270 [ib_uverbs] [ 776.684416] ib_uverbs_remove_one+0x22b/0x420 [ib_uverbs] [ 776.685371] remove_client_context+0xa6/0xf0 [ib_core] [ 776.686342] disable_device+0x12b/0x240 [ib_core] [ 776.687249] __ib_unregister_device+0x269/0x460 [ib_core] [ 776.688233] ib_unregister_device+0x21/0x30 [ib_core] [ 776.689140] mlx5r_remove+0xd0/0x170 [mlx5_ib] [ 776.689999] device_release_driver_internal+0x3b2/0x5 ---truncated---
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/426f54f20b79c5b164a0472ad3f6ba36afcd08c6
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/a44a3f175eaee7e5aeb6a8fed381c4a0d5f49236
Impacted products
Vendor Product Version
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{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/infiniband/core/rdma_core.c",
            "drivers/infiniband/core/uverbs_main.c",
            "include/rdma/uverbs_types.h"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "426f54f20b79c5b164a0472ad3f6ba36afcd08c6",
              "status": "affected",
              "version": "51976c6cd786151b6a1bdf8b8b3334beac0ba99c",
              "versionType": "git"
            },
            {
              "lessThan": "a44a3f175eaee7e5aeb6a8fed381c4a0d5f49236",
              "status": "affected",
              "version": "51976c6cd786151b6a1bdf8b8b3334beac0ba99c",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "0598914a950ddfa694f410e482453cdbb9265515",
              "versionType": "git"
            },
            {
              "status": "affected",
              "version": "86092a4e46d161d24f8106df082e24b8efe87382",
              "versionType": "git"
            },
            {
              "lessThan": "6.12",
              "status": "affected",
              "version": "6.11.11",
              "versionType": "semver"
            },
            {
              "lessThan": "6.13",
              "status": "affected",
              "version": "6.12.2",
              "versionType": "semver"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "drivers/infiniband/core/rdma_core.c",
            "drivers/infiniband/core/uverbs_main.c",
            "include/rdma/uverbs_types.h"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "6.13"
            },
            {
              "lessThan": "6.13",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.2.*",
              "status": "unaffected",
              "version": "7.2.8",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.3",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nRDMA/uverbs: Fix mmap_lock/disassociation_lock circular dependency\n\nCommit 51976c6cd786 (\"RDMA/core: Provide rdma_user_mmap_disassociate()\nto disassociate mmap pages\") introduced disassociation_lock to protect\nnew mmap registrations against uverbs_user_mmap_disassociate(), but\ncreated an ABBA deadlock:\n\n  Thread A (mmap / fork):\n    mmap_lock -\u003e disassociation_lock\n\n  Thread B (disassociate):\n    disassociation_lock -\u003e mmap_lock\n\nFix by removing disassociation_lock entirely and using the pre-existing\nhw_destroy_rwsem instead. hw_destroy_rwsem already provides the same\nprotection: rdma_umap_open() and ib_uverbs_mmap() both use\ndown_read_trylock() before registering a new VMA, so holding hw_destroy_rwsem\nin uverbs_user_mmap_disassociate() is sufficient to block new registrations.\ntrylock is used in both mmap paths (not blocking down_read) because\nmmap_lock is already held on entry, and uverbs_user_mmap_disassociate()\nacquires mmap_lock internally \u2014 a blocking read would recreate the same\ndeadlock.\n\nThe only caller that was not taking hw_destroy_rwsem for write was\nrdma_user_mmap_disassociate(). Fix it to take the rwsem per-ufile while\niterating under lists_mutex.  This is safe because ib_uverbs_close()\nreleases hw_destroy_rwsem entirely before acquiring lists_mutex, so the\ntwo locks are never held simultaneously.\n\nlockdep warning:\n\n [  776.654252] ======================================================\n [  776.655214] WARNING: possible circular locking dependency detected\n [  776.656167] 6.18.0for-upstream_debug_94e244d9ccab #1 Not tainted\n [  776.657114] ------------------------------------------------------\n [  776.658087] devlink/14824 is trying to acquire lock:\n [  776.658879] ffff88811170c800 (\u0026mm-\u003emmap_lock){++++}-{4:4}, at: uverbs_user_mmap_disassociate+0x168/0x780 [ib_uverbs]\n [  776.660479]\n [  776.660479] but task is already holding lock:\n [  776.661460] ffff888142d92b08 (\u0026file-\u003edisassociation_lock){+.+.}-{4:4}, at: uverbs_user_mmap_disassociate+0x39/0x780 [ib_uverbs]\n [  776.663177]\n [  776.663177] which lock already depends on the new lock.\n [  776.663177]\n [  776.664525]\n [  776.664525] the existing dependency chain (in reverse order) is:\n [  776.665724]\n [  776.665724] -\u003e #2 (\u0026file-\u003edisassociation_lock){+.+.}-{4:4}:\n [  776.666887]        __mutex_lock+0x16d/0x2330\n [  776.667633]        rdma_umap_open+0x129/0x280 [ib_uverbs]\n [  776.668489]        dup_mmap+0xa40/0x1790\n [  776.669170]        copy_process+0x5dd2/0x6170\n [  776.669933]        kernel_clone+0xb6/0x610\n [  776.670636]        __do_sys_clone+0xb5/0xf0\n [  776.671354]        do_syscall_64+0x70/0x12e0\n [  776.672083]        entry_SYSCALL_64_after_hwframe+0x4b/0x53\n [  776.672940]\n [  776.672940] -\u003e #1 (\u0026mm-\u003emmap_lock/1){+.+.}-{4:4}:\n [  776.673985]        down_write_nested+0x90/0x1e0\n [  776.674751]        dup_mmap+0x201/0x1790\n [  776.675448]        copy_process+0x5dd2/0x6170\n [  776.676180]        kernel_clone+0xb6/0x610\n [  776.676904]        __do_sys_clone+0xb5/0xf0\n [  776.677615]        do_syscall_64+0x70/0x12e0\n [  776.678351]        entry_SYSCALL_64_after_hwframe+0x4b/0x53\n [  776.679239]\n [  776.679239] -\u003e #0 (\u0026mm-\u003emmap_lock){++++}-{4:4}:\n [  776.680253]        __lock_acquire+0x18c6/0x2ec0\n [  776.681018]        lock_acquire+0x10e/0x2e0\n [  776.681742]        down_read+0x95/0x430\n [  776.682395]        uverbs_user_mmap_disassociate+0x168/0x780 [ib_uverbs]\n [  776.683436]        uverbs_destroy_ufile_hw+0x1ae/0x270 [ib_uverbs]\n [  776.684416]        ib_uverbs_remove_one+0x22b/0x420 [ib_uverbs]\n [  776.685371]        remove_client_context+0xa6/0xf0 [ib_core]\n [  776.686342]        disable_device+0x12b/0x240 [ib_core]\n [  776.687249]        __ib_unregister_device+0x269/0x460 [ib_core]\n [  776.688233]        ib_unregister_device+0x21/0x30 [ib_core]\n [  776.689140]        mlx5r_remove+0xd0/0x170 [mlx5_ib]\n [  776.689999]        device_release_driver_internal+0x3b2/0x5\n---truncated---"
    }
  ],
  "id": "CVE-2026-98431",
  "lastModified": "2026-10-19T10:18:49.857",
  "metrics": {},
  "published": "2026-10-14T14:17:54.887",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/426f54f20b79c5b164a0472ad3f6ba36afcd08c6"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/a44a3f175eaee7e5aeb6a8fed381c4a0d5f49236"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Received"
}



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