2.9 KiB
CVE-2025-38488
Description
In the Linux kernel, the following vulnerability has been resolved:smb: client: fix use-after-free in crypt_message when using async cryptoThe CVE-2024-50047 fix removed asynchronous crypto handling fromcrypt_message(), assuming all crypto operations are synchronous.However, when hardware crypto accelerators are used, this can causeuse-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 forperformance. When crypto_aead_encrypt/decrypt() returns -EINPROGRESS,the operation completes asynchronously. Without crypto_wait_req(),the function immediately frees the request buffer, leading to crasheswhen the driver later accesses the freed memory.This results in a use-after-free condition when the hardware cryptodriver later accesses the freed request structure, leading to kernelcrashes with NULL pointer dereferences.The issue occurs because crypto_alloc_aead() with mask=0 doesn'tguarantee synchronous operation. Even without CRYPTO_ALG_ASYNC inthe 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 completionThis ensures the request buffer isn't freed until the crypto operationcompletes, whether synchronous or asynchronous, while preserving theCVE-2024-50047 fix.
POC
Reference
No PoCs from references.