CVE-2023-52730 in Linux
Summary
by MITRE • 05/21/2024
In the Linux kernel, the following vulnerability has been resolved:
mmc: sdio: fix possible resource leaks in some error paths
If sdio_add_func() or sdio_init_func() fails, sdio_remove_func() can not release the resources, because the sdio function is not presented in these two cases, it won't call of_node_put() or put_device().
To fix these leaks, make sdio_func_present() only control whether device_del() needs to be called or not, then always call of_node_put() and put_device().
In error case in sdio_init_func(), the reference of 'card->dev' is not get, to avoid redundant put in sdio_free_func_cis(), move the get_device() to sdio_alloc_func() and put_device() to sdio_release_func(), it can keep the get/put function be balanced.
Without this patch, while doing fault inject test, it can get the following leak reports, after this fix, the leak is gone.
unreferenced object 0xffff888112514000 (size 2048): comm "kworker/3:2", pid 65, jiffies 4294741614 (age 124.774s) hex dump (first 32 bytes): 00 e0 6f 12 81 88 ff ff 60 58 8d 06 81 88 ff ff ..o.....`X...... 10 40 51 12 81 88 ff ff 10 40 51 12 81 88 ff ff .@Q......@Q..... backtrace: [] kmalloc_trace+0x21/0x110
[] mmc_alloc_card+0x38/0xb0 [mmc_core]
[] mmc_sdio_init_card+0xde/0x170 [mmc_core]
[] mmc_attach_sdio+0xcb/0x1b0 [mmc_core]
[] mmc_rescan+0x54a/0x640 [mmc_core]
unreferenced object 0xffff888112511000 (size 2048): comm "kworker/3:2", pid 65, jiffies 4294741623 (age 124.766s) hex dump (first 32 bytes): 00 40 51 12 81 88 ff ff e0 58 8d 06 81 88 ff ff [email protected]...... 10 10 51 12 81 88 ff ff 10 10 51 12 81 88 ff ff ..Q.......Q..... backtrace: [] kmalloc_trace+0x21/0x110
[] sdio_alloc_func+0x35/0x100 [mmc_core]
[] mmc_attach_sdio.cold.18+0xb1/0x395 [mmc_core]
[] mmc_rescan+0x54a/0x640 [mmc_core]
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Analysis
by VulDB Data Team • 09/23/2025
The vulnerability identified as CVE-2023-52730 resides within the Linux kernel's multimedia card subsystem, specifically affecting the SDIO (Secure Digital Input Output) driver component. This issue manifests as resource leaks occurring during error handling paths when the mmc subsystem attempts to manage SDIO function devices. The problem stems from improper resource management in the sdio_add_func() and sdio_init_func() functions, where the sdio_remove_func() routine fails to properly release allocated resources due to the absence of the sdio function structure in error cases. Such resource leaks can lead to memory exhaustion and system instability over time, particularly under stress conditions or during fault injection testing scenarios.
The technical flaw lies in the conditional execution of resource release functions within the SDIO driver's error handling mechanisms. When sdio_add_func() or sdio_init_func() encounters failures, the sdio_remove_func() function cannot properly execute of_node_put() or put_device() operations because the sdio function structure has not been fully initialized or registered. This creates a scenario where kernel memory allocated for SDIO function devices remains unreleased, leading to memory leaks as evidenced by the kworker processes generating unreferenced object reports. The vulnerability specifically impacts the mmc_core kernel module and demonstrates a classic case of resource management imbalance where acquire and release operations are not properly matched.
The operational impact of this vulnerability extends beyond simple memory leaks to potentially compromise system stability and performance. During fault injection testing, the kernel reports show unreferenced objects of 2048 bytes each, indicating that memory allocated for SDIO card and function structures remains allocated even after error conditions have occurred. These memory leaks can accumulate over time, leading to reduced system performance, increased memory pressure, and potential system crashes. The vulnerability affects any system utilizing SDIO devices through the mmc subsystem, including wireless network adapters, Bluetooth modules, and other peripheral devices that rely on SDIO interfaces.
The fix implemented addresses the resource leak by modifying the sdio_func_present() function to control only whether device_del() needs to be called, while ensuring that of_node_put() and put_device() are always executed regardless of error conditions. Additionally, the patch restructures the reference counting mechanism by moving get_device() calls to sdio_alloc_func() and put_device() to sdio_release_func(), thereby maintaining proper balance between acquire and release operations. This solution aligns with CWE-404, which addresses improper resource release or unbalanced resource management, and follows ATT&CK technique T1490 for resource exhaustion through memory leaks. The patch ensures that all allocated resources are properly released during error paths, preventing the accumulation of unreferenced objects and maintaining system stability under fault injection testing conditions.