medium CVSS 5.5

CVE-2025-21885·Kernel vulnerability

In the Linux kernel, the following vulnerability has been resolved: RDMA/bnxt_re: Fix the page details for the srq created by kernel consumers While using nvme target with use_srq on, below kernel panic is noticed. [ 549.698111] bnxt_en 0000:41:00.0 enp65s0np0: FEC autoneg off encoding: Clause 91 RS(544,514) [ 566.393619] Oops: divide error: 0000 [#1] PREEMPT SMP NOPTI .. [ 566.393799] <TASK> [ 566.393807] ? __die_body+0x1a/0x60 [ 566.393823] ? die+0x38/0x60 [ 566.393835] ? do_trap+0xe4/0x110 [ 566.393847] ? bnxt_qplib_alloc_init_hwq+0x1d4/0x580 [bnxt_re] [ 566.393867] ? bnxt_qplib_alloc_init_hwq+0x1d4/0x580 [bnxt_re] [ 566.393881] ? do_error_trap+0x7c/0x120 [ 566.393890] ? bnxt_qplib_alloc_init_hwq+0x1d4/0x580 [bnxt_re] [ 566.393911] ? exc_divide_error+0x34/0x50 [ 566.393923] ? bnxt_qplib_alloc_init_hwq+0x1d4/0x580 [bnxt_re] [ 566.393939] ? asm_exc_divide_error+0x16/0x20 [ 566.393966] ? bnxt_qplib_alloc_init_hwq+0x1d4/0x580 [bnxt_re] [ 566.393997] bnxt_qplib_create_srq+0xc9/0x340 [bnxt_re] [ 566.394040] bnxt_re_create_srq+0x335/0x3b0 [bnxt_re] [ 566.394057] ? srso_return_thunk+0x5/0x5f [ 566.394068] ? __init_swait_queue_head+0x4a/0x60 [ 566.394090] ib_create_srq_user+0xa7/0x150 [ib_core] [ 566.394147] nvmet_rdma_queue_connect+0x7d0/0xbe0 [nvmet_rdma] [ 566.394174] ? lock_release+0x22c/0x3f0 [ 566.394187] ? srso_return_thunk+0x5/0x5f Page size and shift info is set only for the user space SRQs. Set page size and page shift for kernel space SRQs also.

Severity
medium
Software
Kernel
Fixed in
6.13.6
Published
2025-03-27

Affected versions

From: 6.13

Until: 6.13.6

Fixed in: 6.13.6

How to fix this CVE

Update your Linux kernel to version 6.13.6 or later to resolve this divide-by-zero error in the RDMA bnxt_re driver. The vulnerability occurs when NVMe target mode is enabled with SRQ (Shared Receive Queue) functionality, causing kernel panics during SRQ allocation. Apply the kernel update immediately to systems running kernel versions 6.13.0 through 6.13.5.

sudo dnf update kernel kernel-devel

Defensia detects this vulnerability

How to check if you are affected

  1. Check your current kernel version: uname -r
  2. Verify if bnxt_re (Broadcom RDMA) driver is loaded: lsmod | grep bnxt_re
  3. Check for NVMe target configuration: cat /sys/kernel/config/nvmet/*/subsystems/*/use_srq 2>/dev/null || echo 'NVMe target not configured'
  4. Inspect kernel logs for divide error panics: dmesg | grep -i 'divide error\|bnxt_qplib_alloc_init_hwq'
  5. Verify kernel update: uname -r should show version 6.13.6 or later after patching

FAQ

What is CVE-2025-21885?

This is a divide-by-zero vulnerability in the Linux kernel's RDMA bnxt_re driver that occurs when kernel consumers (such as NVMe target) create Shared Receive Queues (SRQ) without proper page size initialization, leading to kernel panics and system instability.

Is CVE-2025-21885 being actively exploited?

No, this vulnerability is not listed on CISA's Known Exploited Vulnerabilities (KEV) catalog and no public exploits are available. However, it can be triggered reliably by administrators running NVMe target with SRQ enabled.

What versions of Kernel are affected by CVE-2025-21885?

Linux kernel versions 6.13.0 through 6.13.5 are affected. The vulnerability was patched in kernel 6.13.6.

How do I check if my server is vulnerable to CVE-2025-21885?

Run 'uname -r' to check your kernel version. If it shows 6.13.0 through 6.13.5, and you have bnxt_re driver loaded (verify with 'lsmod | grep bnxt_re'), your system is vulnerable if NVMe target SRQ is in use.

Does Defensia detect CVE-2025-21885?

Yes — Defensia's CVE advisory scanner compares installed package versions against the NVD database. If Linux kernel is installed on a monitored server, CVE-2025-21885 will appear in your dashboard with remediation steps.

Related Kernel CVEs

CVE-2026-64439CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: crypto: krb5 - filter out async aead implementations at alloc krb5_aead_encrypt(), krb5_aead_decrypt() in rfc3961_simplified.c and rfc8009_encrypt(), rfc8009_decrypt() in rfc8009_aes2.c set a NULL completion callback and treat any negative return from crypto_aead_{encrypt,decrypt}() as terminal, falling through to kfree_sensitive(buffer). When the encrypt_name resolves to an async AEAD instance the request returns -EINPROGRESS, the buffer is freed while the backend's worker still holds a pointer, and the worker dereferences the freed slab on completion. KASAN report under UML+SLUB with a synthetic async aead backend bound to krb5->encrypt_name: BUG: KASAN: slab-use-after-free in t5_stub_complete+0x7d/0xc7 The helpers were written synchronously, so filter the async instances out at allocation time instead of plumbing crypto_wait_req() through every call site. Reachable via net/rxrpc/rxgk.c, fs/afs/cm_security.c and net/ceph/crypto.c on systems with an async AEAD provider bound to the krb5 enctype name.
CVE-2026-100075CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: RDMA/srpt: Fix srpt_alloc_rw_ctxs() unwind counters When srpt_alloc_rw_ctxs() fails partway through a multi-buffer indirect descriptor, the unwind path destroys RDMA contexts but leaves stale n_rw_ctx and n_rdma values (and a dangling rw_ctxs pointer). Later sq_wr_avail accounting in srpt_queue_response() or srpt_write_pending() can then subtract the wrong number of send queue credits. Reset the counters and clear rw_ctxs after freeing the heap allocation before returning an error.
CVE-2026-64067CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: netfs: Fix missing barriers when accessing stream->subrequests locklessly The list of subrequests attached to stream->subrequests is accessed without locks by netfs_collect_read_results() and netfs_collect_write_results(), and then they access subreq->flags without taking a barrier after getting the subreq pointer from the list. Relatedly, the functions that build the list don't use any sort of write barrier when constructing the list to make sure that the NETFS_SREQ_IN_PROGRESS flag is perceived to be set first if no lock is taken. Fix this by: (1) Add a new list_add_tail_release() function that uses a release barrier to set the pointer to the new member of the list. (2) Add a new list_first_entry_or_null_acquire() function that uses an acquire barrier to read the pointer to the first member in a list (or return NULL). (3) Use list_add_tail_release() when adding a subreq to ->subrequests. (4) Use list_first_entry_or_null_acquire() when initially accessing the front of the list (when an item is removed, the pointer to the new front iterm is obtained under the same lock).
CVE-2026-64068CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: netfs: Fix missing locking around retry adding new subreqs Fix netfs_retry_read_subrequests() and netfs_retry_write_stream() to take the appropriate lock when adding extra subrequests into stream->subrequests.
CVE-2026-64355CVSS 9.8In the Linux kernel, the following vulnerability has been resolved: bpf: Reject fragmented frames in devmap Devmap broadcast redirects clone the packet for all but the last destination. For native XDP, that clone path copies only the linear xdp_frame data, while fragmented frames keep skb_shared_info in tailroom outside the linear area. Cloning such a frame leaves XDP_FLAGS_HAS_FRAGS set but without valid frag metadata, and the later free path can interpret uninitialized tail data as skb_shared_info, leading to an out-of-bounds access during frame return. Reject fragmented native XDP frames in dev_map_enqueue_clone(). Add the same restriction to the generic XDP clone path in dev_map_redirect_clone(). Generic XDP represents fragmented packets as nonlinear skbs, and rejecting them here keeps clone-based broadcast support aligned between native and generic XDP.

References

Track CVEs across your fleet automatically

Defensia scans your Linux servers and tells you exactly which ones are running vulnerable versions — including CVE-2025-21885. Free for 1 server.

Get started free