{"id":"CVE-2026-98431","revision":"f459c697e4cd497ebbb11d202df24be3","records":[{"revision":"f459c697e4cd497ebbb11d202df24be3","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-98431","aliases":[],"title":"RDMA/uverbs: Fix mmap_lock/disassociation_lock circular dependency","description":"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 -> disassociation_lock\n\n Thread B (disassociate):\n disassociation_lock -> 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 — 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 (&mm->mmap_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 (&file->disassociation_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] -> #2 (&file->disassociation_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] -> #1 (&mm->mmap_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] -> #0 (&mm->mmap_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---","state":0,"publishedAt":"2026-10-14T13:27:56.162+00:00","modifiedAt":"2026-10-19T09:19:26.316+00:00","affected":[{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n \"product\": \"Linux\",\n \"vendor\": \"Linux\",\n \"defaultStatus\": \"unaffected\",\n \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n \"programFiles\": [\n \"drivers/infiniband/core/rdma_core.c\",\n \"drivers/infiniband/core/uverbs_main.c\",\n \"include/rdma/uverbs_types.h\"\n ],\n \"versions\": [\n {\n \"version\": \"51976c6cd786151b6a1bdf8b8b3334beac0ba99c\",\n \"lessThan\": \"426f54f20b79c5b164a0472ad3f6ba36afcd08c6\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"51976c6cd786151b6a1bdf8b8b3334beac0ba99c\",\n \"lessThan\": \"a44a3f175eaee7e5aeb6a8fed381c4a0d5f49236\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"0598914a950ddfa694f410e482453cdbb9265515\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"86092a4e46d161d24f8106df082e24b8efe87382\",\n \"status\": \"affected\",\n \"versionType\": \"git\"\n },\n {\n \"version\": \"6.11.11\",\n \"lessThan\": \"6.12\",\n \"status\": \"affected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"6.12.2\",\n \"lessThan\": \"6.13\",\n \"status\": \"affected\",\n \"versionType\": \"semver\"\n }\n ]\n }"},{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n \"product\": \"Linux\",\n \"vendor\": \"Linux\",\n \"defaultStatus\": \"affected\",\n \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n \"programFiles\": [\n \"drivers/infiniband/core/rdma_core.c\",\n \"drivers/infiniband/core/uverbs_main.c\",\n \"include/rdma/uverbs_types.h\"\n ],\n \"versions\": [\n {\n \"version\": \"6.13\",\n \"status\": \"affected\"\n },\n {\n \"version\": \"0\",\n \"lessThan\": \"6.13\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"7.2.8\",\n \"lessThanOrEqual\": \"7.2.*\",\n \"status\": \"unaffected\",\n \"versionType\": \"semver\"\n },\n {\n \"version\": \"7.3\",\n \"lessThanOrEqual\": \"*\",\n \"status\": \"unaffected\",\n \"versionType\": \"original_commit_for_fix\"\n }\n ]\n }"}],"metrics":[],"references":["https://git.kernel.org/stable/c/426f54f20b79c5b164a0472ad3f6ba36afcd08c6","https://git.kernel.org/stable/c/a44a3f175eaee7e5aeb6a8fed381c4a0d5f49236"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-98431","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-98431","identifiers":["CVE-2026-98431"]},"retained":false,"historicalAffected":[]}],"coverage":[]}