Summary
In the Linux kernel, the following vulnerability has been resolved: smb: client: fix crypto...
In the Linux kernel, the following vulnerability has been resolved:
smb: client: fix crypto buffers in non-linear memory
The crypto API, through the scatterlist API, expects input buffers to be
in linear memory. We handle this with the cifs_sg_set_buf() helper
that converts vmalloc'd memory to their corresponding pages.
However, when we allocate our aead_request buffer (@creq in
smb2ops.c::crypt_message()), we do so with kvzalloc(), which possibly
puts aead_request->__ctx in vmalloc area.
AEAD algorithm then uses ->__ctx for its private/internal data and
operations, and uses sg_set_buf() for such data on a few places.
This works fine as long as @creq falls into kmalloc zone (small
requests) or vmalloc'd memory is still within linear range.
Tasks' stacks are vmalloc'd by default (CONFIG_VMAP_STACK=y), so too
many tasks will increment the base stacks' addresses to a point where
virt_addr_valid(buf) will fail (BUG() in sg_set_buf()) when that
happens.
In practice: too many parallel reads and writes on an encrypted mount
will trigger this bug.
To fix this, always alloc @creq with kmalloc() instead.
Also drop the @sensitive_size variable/arguments since
kfree_sensitive() doesn't need it.
Backtrace:
[ 945.272081] ------------[ cut here ]------------
[ 945.272774] kernel BUG at include/linux/scatterlist.h:209!
[ 945.273520] Oops: invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC NOPTI
[ 945.274412] CPU: 7 UID: 0 PID: 56 Comm: kworker/u33:0 Kdump: loaded Not tainted 6.15.0-lku-11779-g8e9d6efccdd7-dirty #1 PREEMPT(voluntary)
[ 945.275736] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.16.3-2-gc13ff2cd-prebuilt.qemu.org 04/01/2014
[ 945.276877] Workqueue: writeback wb_workfn (flush-cifs-2)
[ 945.277457] RIP: 0010:crypto_gcm_init_common+0x1f9/0x220
[ 945.278018] Code: b0 00 00 00 48 83 c4 08 5b 5d 41 5c 41 5d 41 5e 41 5f c3 cc cc cc cc 48 c7 c0 00 00 00 80 48 2b 05 5c 58 e5 00 e9 58 ff ff ff <0f> 0b 0f 0b 0f 0b 0f 0b 0f 0b 0f 0b 48 c7 04 24 01 00 00 00 48 8b
[ 945.279992] RSP: 0018:ffffc90000a27360 EFLAGS: 00010246
[ 945.280578] RAX: 0000000000000000 RBX: ffffc90001d85060 RCX: 0000000000000030
[ 945.281376] RDX: 0000000000080000 RSI: 0000000000000000 RDI: ffffc90081d85070
[ 945.282145] RBP: ffffc90001d85010 R08: ffffc90001d85000 R09: 0000000000000000
[ 945.282898] R10: ffffc90001d85090 R11: 0000000000001000 R12: ffffc90001d85070
[ 945.283656] R13: ffff888113522948 R14: ffffc90001d85060 R15: ffffc90001d85010
[ 945.284407] FS: 0000000000000000(0000) GS:ffff8882e66cf000(0000) knlGS:0000000000000000
[ 945.285262] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 945.285884] CR2: 00007fa7ffdd31f4 CR3: 000000010540d000 CR4: 0000000000350ef0
[ 945.286683] Call Trace:
[ 945.286952]
[ 945.287184] ? crypt_message+0x33f/0xad0 [cifs]
[ 945.287719] crypto_gcm_encrypt+0x36/0xe0
[ 945.288152] crypt_message+0x54a/0xad0 [cifs]
[ 945.288724] smb3_init_transform_rq+0x277/0x300 [cifs]
[ 945.289300] smb_send_rqst+0xa3/0x160 [cifs]
[ 945.289944] cifs_call_async+0x178/0x340 [cifs]
[ 945.290514] ? __pfx_smb2_writev_callback+0x10/0x10 [cifs]
[ 945.291177] smb2_async_writev+0x3e3/0x670 [cifs]
[ 945.291759] ? find_held_lock+0x32/0x90
[ 945.292212] ? netfs_advance_write+0xf2/0x310
[ 945.292723] netfs_advance_write+0xf2/0x310
[ 945.293210] netfs_write_folio+0x346/0xcc0
[ 945.293689] ? __pfx__raw_spin_unlock_irq+0x10/0x10
[ 945.294250] netfs_writepages+0x117/0x460
[ 945.294724] do_writepages+0xbe/0x170
[ 945.295152] ? find_held_lock+0x32/0x90
[ 945.295600] ? kvm_sched_clock_read+0x11/0x20
[ 945.296103] __writeback_single_inode+0x56/0x4b0
[ 945.296643] writeback_sb_inodes+0x229/0x550
[ 945.297140] __writeback_inodes_wb+0x4c/0xe0
[ 945.297642] wb_writeback+0x2f1/0x3f0
[ 945.298069] wb_workfn+0x300/0x490
[ 945.298472] process_one_work+0x1fe/0x590
[ 945.298949] worker_thread+0x1ce/0x3c0
[ 945.299397] ? __pfx_worker_thread+0x10/0x10
[ 945.299900] kthr
---truncated---
Impact
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
Already deployed Kodem?
See it in your environmentNew to Kodem? Get a demo →Remediation advice
Frequently Asked Questions
- What is CVE-2025-40052? CVE-2025-40052 is a unknown-severity security vulnerability. No fixed version is listed yet.
- Is there a fix for CVE-2025-40052? No fixed version is listed for CVE-2025-40052 yet. Monitor the advisory for updates and apply mitigations in the interim.
- Is CVE-2025-40052 exploitable, and should I be worried? Whether CVE-2025-40052 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2025-40052 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.