HIGH Introduced in 5.10
ucma SetPath UAF
CVE-2026-89508
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
KernelScan AI6.9MEDIUM
01Description
In the Linux kernel, the following vulnerability has been resolved: RDMA/ucma: Lock the handler in ucma_set_ib_path() ucma_set_ib_path() calls ucma_event_handler() straight from the write() path, without the handler lock that keeps ctx->file stable while a uevent is queued. The handler re-reads ctx->file for every dereference: mutex_lock(&ctx->file->mut); /* file A */ list_add_tail(&uevent->list, &ctx->file->event_list); /* file B */ mutex_unlock(&ctx->file->mut); /* file B */ wake_up_interruptible(&ctx->file->poll_wait); /* file B */ A concurrent ucma_migrate_id() reassigns ctx->file while the SET_OPTION caller sleeps in mutex_lock(), so the list_add_tail() lands on file B's event_list while only file A's mutex is held, racing every other user of that list: BUG: KASAN: slab-use-after-free in __list_add_valid_or_report+0x1aa/0x1c0 Read of size 8 at addr ffff888153c6a418 by task poc_corr/486 Call Trace: __list_add_valid_or_report+0x1aa/0x1c0 ucma_event_handler+0x1be/0xc00 ucma_set_ib_path+0x45e/0x710 ucma_set_option+0x32e/0x590 ucma_write+0x1f9/0x330 Allocated by task 505: ucma_write_cm_event+0x1a1/0x660 Freed by task 505: kfree+0x1da/0x4c0 ucma_get_event+0x5d5/0x7e0 The freed object is a ucma_event that another thread dequeued from file B's list under file B's mutex. File A's mut is left held on top of that, wedging its next writer in uninterruptible sleep. This path needs a bound and address-resolved cm_id, so it requires an RDMA device to be present. Take the handler lock around the call.
02KernelScan AI Analysis
Risk summary
A local user with access to the RDMA CM device can exploit a race condition to trigger a use-after-free in kernel memory, potentially achieving arbitrary read/write and denial of service. The bug requires an RDMA device to be present and bound, limiting exposure to systems with InfiniBand or RoCE hardware. Exploitation depends on winning a narrow timing window between two concurrent operations.
Vulnerability analysis
A race condition in the RDMA connection manager allows a local attacker to trigger a use-after-free in kernel heap memory. When a user sets a path option through the device's write path, an internal handler runs without a required lock that keeps the connection context's associated file stable. A concurrent migration operation can reassign that file while the handler is executing, causing list operations to target the wrong event list without proper synchronization. This corrupts list state, frees objects still in use, and can leave a kernel lock permanently held. The fix adds the missing lock around the handler so the file association cannot change during execution. The vulnerable path is reachable locally by any user who can open the RDMA connection manager device and requires RDMA hardware to be present and configured on the system.
Lifecycle
03Fix Versions
| Branch | Introduced | Fixed in | Patch commit |
|---|---|---|---|
| 5.10 | 5.10 | 5.10.270 | 3dd07b369371 |
| 5.15 | 5.10 | 5.15.221 | b2da0d488a1c |
| 6.12 | 5.10 | 6.12.109 | 764586f8f618 |
| 6.18 | 5.10 | 6.18.50 | 28ac2dd41648 |
| 7.2 | 5.10 | 7.2.4 | 43a7d8ae9f64 |
| 6.6 | 5.10 | 6.6.157 | 71dc206f2e2a |
| 6.1 | 5.10 | 6.1.188 | a7f8d26e653e |
| mainline | 5.10 | 7.3-rc1 | ecbe7d36dc2d |
| cip/6.12 | 5.10 | 6.12.111-cip32 | 764586f8f618 |