Linux Kernel up to 7.2.5 smbdirect mm/slub.c smbdirect_accept_connect_request null pointer dereference

Summaryinfo

A vulnerability identified as critical has been detected in Linux Kernel up to 7.2.5. Affected by this vulnerability is the function smbdirect_accept_connect_request of the file mm/slub.c of the component smbdirect. This manipulation causes null pointer dereference. This vulnerability is handled as CVE-2026-90172. The attack can be initiated remotely. There is not any exploit available. You should upgrade the affected component.

Detailsinfo

A vulnerability was found in Linux Kernel up to 7.2.5. It has been declared as critical. Affected by this vulnerability is the function smbdirect_accept_connect_request of the file mm/slub.c of the component smbdirect. The manipulation with an unknown input leads to a null pointer dereference vulnerability. The CWE definition for the vulnerability is CWE-476. A NULL pointer dereference occurs when the application dereferences a pointer that it expects to be valid, but is NULL, typically causing a crash or exit. As an impact it is known to affect availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: smb: smbdirect: destroy QP before mem pools on accept failure On the rdma_accept_failed error path of smbdirect_accept_connect_request(), the receive io posted just above is owned by the QP (recv_io is set to NULL after a successful post). The error path fell through to smbdirect_connection_destroy_mem_pools() before smbdirect_connection_destroy_qp(), so the mem pools and the recv_io slab cache were destroyed while that recv_io was still outstanding on the QP. The drain in smbdirect_connection_destroy_qp() (ib_drain_qp()) is what runs the recv completion that returns the recv_io to the free list, so destroying the pools first leaves the object outstanding at kmem_cache_destroy() time ("Slab cache still has objects") and later frees it into an already-destroyed mempool (mempool_free_bulk NULL-pointer dereference). Give rdma_accept_failed its own teardown that drains the QP first, then destroys the mem pools, and returns. The remaining labels (post_recv_io_failed onward) run before the recv_io was ever posted, so they keep the mem-pools-then-qp order. The outstanding recv_io at kmem_cache_destroy() time: [ 3487.344647] ============================================================================= [ 3487.349942] BUG smbdirect_recv_io_cache_ffff88811ba99000 (Not tainted): Objects remaining on __kmem_cache_shutdown() [ 3487.356078] ----------------------------------------------------------------------------- [ 3487.356078] [ 3487.356738] Object 0xffff8881511c3440 @offset=13376 [ 3487.358464] Allocated in mempool_alloc_noprof+0x18c/0x290 age=1194 cpu=6 pid=22254 [ 3487.361197] mempool_alloc_noprof+0x18c/0x290 [ 3487.361542] smbdirect_connection_create_mem_pools+0x405/0x780 [ 3487.361972] smbdirect_accept_connect_request+0x5a8/0x1b80 [ 3487.362359] smbdirect_listen_rdma_event_handler+0x1579/0x1b90 [ 3487.362779] cma_cm_event_handler+0x9c/0x230 [ 3487.363096] cma_ib_req_handler+0x2682/0x45d0 [ 3487.363414] cm_process_work+0x56/0x3d0 [ 3487.363676] cm_work_handler+0x8a0e/0xd000 [ 3487.367496] process_scheduled_works+0xa07/0x13a0 [ 3487.367859] worker_thread+0x7c9/0xc80 [ 3487.368148] kthread+0x341/0x430 [ 3487.368407] ret_from_fork+0x3a8/0x7a0 [ 3487.368704] ret_from_fork_asm+0x1a/0x30 [ 3487.370307] Slab 0xffffea0005447000 objects=19 used=1 fp=0xffff8881511c0040 flags=0x100000000000240(workingset|head|node=0|zone=2) [ 3487.372840] ------------[ cut here ]------------ [ 3487.373195] WARNING: mm/slub.c:1244 at __slab_err+0x1a/0x30, CPU#6: kworker/6:84/22254 [ 3487.373759] Modules linked in: [ 3487.373993] CPU: 6 UID: 0 PID: 22254 Comm: kworker/6:84 Tainted: G B 7.1.0-next-20260623+ #88 PREEMPT(lazy) [ 3487.374778] Tainted: [B]=BAD_PAGE [ 3487.377830] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.17.0-debian-1.17.0-1 04/01/2014 [ 3487.378515] Workqueue: ib_cm cm_work_handler [ 3487.378820] RIP: 0010:__slab_err+0x1a/0x30 [ 3487.379129] Code: 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f 1f 44 00 00 e8 36 00 00 00 bf 05 00 00 00 be 01 00 00 00 e8 f7 75 45 00 90 <0f> 0b 90 c3 cc cc cc cc cc 66 66 66 66 2e 0f 1f 84 00 00 00 00 00 [ 3487.383255] RSP: 0018:ffff888220fc7050 EFLAGS: 00010093 [ 3487.383643] RAX: ffffffff8168e60a RBX: ffff88810955e640 RCX: ffff88821c381d80 [ 3487.384158] RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff870fa080 [ 3487.384662] RBP: ffff888220fc7068 R08: ffffffff870fa087 R09: 1ffffffff0e1f410 [ 3487.385192] R10: dffffc0000000000 R11: fffffbfff0e1f411 R12: ffffea0005447210 [ 3487.385674] R13: ffffea0005447000 R14: ffff888220fc7068 R15: ffff88812a8ab300 [ 3487.388932] FS: 0000000000000000(0000) GS:ffff888427e76000(0000) knlGS:0000000000000000 [ 3487.389529] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 3487.389934] CR2: 00007ffcf2d84fd8 CR3: 0000000111d64006 CR4: 0000000000f72ef0 [ 3487.390440] PKRU: 55555554 [ 3487.390641] Call Trace: [ 3487.390826] <TASK> [ 3 ---truncated---

The advisory is shared at git.kernel.org. This vulnerability is known as CVE-2026-90172 since 09/11/2026. The exploitation appears to be easy. The attack can be launched remotely. Technical details are known, but no exploit is available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 09/17/2026).

Upgrading to version 7.2.6 or 7.3-rc1 eliminates this vulnerability. Applying the patch 959813a3752b459ed77b0b3eaf30b9f4c6204260/383a9480f5f40bc46454cce27ccfad532cedad9c is able to eliminate this problem. The best possible mitigation is suggested to be upgrading to the latest version.

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 7.2.0
• 7.2.1
• 7.2.2
• 7.2.3
• 7.2.4
• 7.2.5

License

• open-source

Website

• Vendor: https://www.kernel.org/

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Entryinfo

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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