CVE-2025-38488 (GCVE-0-2025-38488)
Vulnerability from cvelistv5
Published
2025-07-28 11:21
Modified
2026-08-05 12:02
Severity ?
9.8 (Critical) - CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: smb: client: fix use-after-free in crypt_message when using async crypto The CVE-2024-50047 fix removed asynchronous crypto handling from crypt_message(), assuming all crypto operations are synchronous. However, when hardware crypto accelerators are used, this can cause use-after-free crashes: crypt_message() // Allocate the creq buffer containing the req creq = smb2_get_aead_req(..., &req); // Async encryption returns -EINPROGRESS immediately rc = enc ? crypto_aead_encrypt(req) : crypto_aead_decrypt(req); // Free creq while async operation is still in progress kvfree_sensitive(creq, ...); Hardware crypto modules often implement async AEAD operations for performance. When crypto_aead_encrypt/decrypt() returns -EINPROGRESS, the operation completes asynchronously. Without crypto_wait_req(), the function immediately frees the request buffer, leading to crashes when the driver later accesses the freed memory. This results in a use-after-free condition when the hardware crypto driver later accesses the freed request structure, leading to kernel crashes with NULL pointer dereferences. The issue occurs because crypto_alloc_aead() with mask=0 doesn't guarantee synchronous operation. Even without CRYPTO_ALG_ASYNC in the mask, async implementations can be selected. Fix by restoring the async crypto handling: - DECLARE_CRYPTO_WAIT(wait) for completion tracking - aead_request_set_callback() for async completion notification - crypto_wait_req() to wait for operation completion This ensures the request buffer isn't freed until the crypto operation completes, whether synchronous or asynchronous, while preserving the CVE-2024-50047 fix.
References
Impacted products
Vendor Product Version
Linux Linux Version: 8f14a476abba13144df5434871a7225fd29af633
Version: ef51c0d544b1518b35364480317ab6d3468f205d
Version: bce966530fd5542bbb422cb45ecb775f7a1a6bc3
Version: 0809fb86ad13b29e1d6d491364fc7ea4fb545995
Version: b0abcd65ec545701b8793e12bc27dc98042b151a
Version: b0abcd65ec545701b8793e12bc27dc98042b151a
Version: b0abcd65ec545701b8793e12bc27dc98042b151a
Version: 538c26d9bf70c90edc460d18c81008a4e555925a
Version: 5.10.237   ≤
Version: 5.15.181   ≤
Version: 6.1.128   ≤
Version: 6.6.57   ≤
Version: 6.11.4   ≤
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nsmb: client: fix use-after-free in crypt_message when using async crypto\n\nThe CVE-2024-50047 fix removed asynchronous crypto handling from\ncrypt_message(), assuming all crypto operations are synchronous.\nHowever, when hardware crypto accelerators are used, this can cause\nuse-after-free crashes:\n\n  crypt_message()\n    // Allocate the creq buffer containing the req\n    creq = smb2_get_aead_req(..., \u0026req);\n\n    // Async encryption returns -EINPROGRESS immediately\n    rc = enc ? crypto_aead_encrypt(req) : crypto_aead_decrypt(req);\n\n    // Free creq while async operation is still in progress\n    kvfree_sensitive(creq, ...);\n\nHardware crypto modules often implement async AEAD operations for\nperformance. When crypto_aead_encrypt/decrypt() returns -EINPROGRESS,\nthe operation completes asynchronously. Without crypto_wait_req(),\nthe function immediately frees the request buffer, leading to crashes\nwhen the driver later accesses the freed memory.\n\nThis results in a use-after-free condition when the hardware crypto\ndriver later accesses the freed request structure, leading to kernel\ncrashes with NULL pointer dereferences.\n\nThe issue occurs because crypto_alloc_aead() with mask=0 doesn\u0027t\nguarantee synchronous operation. Even without CRYPTO_ALG_ASYNC in\nthe mask, async implementations can be selected.\n\nFix by restoring the async crypto handling:\n- DECLARE_CRYPTO_WAIT(wait) for completion tracking\n- aead_request_set_callback() for async completion notification\n- crypto_wait_req() to wait for operation completion\n\nThis ensures the request buffer isn\u0027t freed until the crypto operation\ncompletes, whether synchronous or asynchronous, while preserving the\nCVE-2024-50047 fix."
        }
      ],
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            "baseScore": 9.8,
            "baseSeverity": "CRITICAL",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
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              "value": "AV:N - The decrypt path of crypt_message() processes SMB3 transform PDUs received from the remote server (smb3_receive_transform \u2192 receive_encrypted_read/standard \u2192 decrypt_raw_data), and the server itself dictates whether encryption is used via SMB2_SESSION_FLAG_ENCRYPT_DATA/SHI1005_FLAGS_ENCRYPT_DATA, so a remote SMB peer drives the vulnerable code over TCP/445.\nAC:L - There is no race the attacker must win: on any target whose crypto API binds gcm(aes)/ccm(aes) to an async hardware accelerator (CAAM, CCP, Chelsio, HiSilicon, Tegra, STM32 and ~24 other in-tree drivers, ubiquitous on embedded and enterprise hardware), every single encrypted SMB message frees the in-flight request buffer deterministically, and the attacker further controls message size and rate to time heap reuse.\nPR:N - The attacker is the remote SMB server (or an attacker who has compromised it) and holds no privileges whatsoever on the vulnerable client; it can even mandate encryption itself, so no local account or credential on the target is required.\nUI:N - Against an already-mounted share (fstab/autofs/persistent enterprise mounts) the server can emit encrypted responses and unsolicited oplock/lease-break messages that reach crypt_message() with no action by any user on the client.\nS:U - The use-after-free corrupts kernel slab memory within the same security authority as the affected component; no VM, IOMMU, or sandbox boundary is crossed.\nC:H - The freed allocation holds the scatterlist that the crypto driver walks to place decrypted output and the driver\u0027s private DMA context, so reallocation of that slab lets the hardware write plaintext into attacker-chosen memory and exposes kernel data, giving an arbitrary-read-grade disclosure primitive.\nI:H - The freed buffer contains req-\u003ebase.complete and req-\u003ebase.data, later invoked as req-\u003ecomplete(req-\u003edata, err), plus the sg pointers used for output DMA; spraying the freed slab during the accelerator round-trip yields a controlled indirect call and arbitrary kernel writes.\nA:H - Even without exploitation the defect reliably produces a slab use-after-free and NULL-pointer dereference in the crypto completion path, as documented in the changelog, crashing the kernel on every encrypted SMB message."
            }
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        "dateUpdated": "2026-08-05T12:02:19.784Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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          "url": "https://git.kernel.org/stable/c/5d047b12f86cc3b9fde1171c02d9bccf4dba0632"
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        {
          "url": "https://git.kernel.org/stable/c/6550b2bef095d0dd2d2c8390d2ea4c3837028833"
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        {
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        {
          "url": "https://git.kernel.org/stable/c/15a0a5de49507062bc3be4014a403d8cea5533de"
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        {
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        {
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        {
          "url": "https://git.kernel.org/stable/c/b220bed63330c0e1733dc06ea8e75d5b9962b6b6"
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      "title": "smb: client: fix use-after-free in crypt_message when using async crypto",
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  "cveMetadata": {
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    "assignerShortName": "Linux",
    "cveId": "CVE-2025-38488",
    "datePublished": "2025-07-28T11:21:52.085Z",
    "dateReserved": "2025-04-16T04:51:24.021Z",
    "dateUpdated": "2026-08-05T12:02:19.784Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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