CVE-2023-53641

Description

In the Linux kernel, the following vulnerability has been resolved: wifi: ath9k: hif_usb: fix memory leak of remain_skbs hif_dev->remain_skb is allocated and used exclusively in ath9k_hif_usb_rx_stream(). It is implied that an allocated remain_skb is processed and subsequently freed (in error paths) only during the next call of ath9k_hif_usb_rx_stream(). So, if the urbs are deallocated between those two calls due to the device deinitialization or suspend, it is possible that ath9k_hif_usb_rx_stream() is not called next time and the allocated remain_skb is leaked. Our local Syzkaller instance was able to trigger that. remain_skb makes sense when receiving two consecutive urbs which are logically linked together, i.e. a specific data field from the first skb indicates a cached skb to be allocated, memcpy'd with some data and subsequently processed in the next call to ath9k_hif_usb_rx_stream(). Urbs deallocation supposedly makes that link irrelevant so we need to free the cached skb in those cases. Fix the leak by introducing a function to explicitly free remain_skb (if it is not NULL) when the rx urbs have been deallocated. remain_skb is NULL when it has not been allocated at all (hif_dev struct is kzalloced) or when it has been processed in next call to ath9k_hif_usb_rx_stream(). Found by Linux Verification Center (linuxtesting.org) with Syzkaller.

CVSS Details

CVSS Score

5.5

Severity

MEDIUM

CVSS Vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Configurations (Affected Products)

cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* - VULNERABLE

Linux kernel < 6.1.63

Linux kernel 6.2.x < 6.2.13

Linux kernel 6.3.x < 6.3.2

Linux kernel 6.4.x < 6.4.10

Linux kernel 6.5.x < 6.5.5

Linux kernel 6.6.x < 6.6

PoC / Exploit Code

⚠ For Security Research Only

The following code is for security research and authorized testing only.

python

// CVE-2023-53641 PoC - Triggering remain_skb memory leak in ath9k hif_usb
// This PoC demonstrates how to trigger the memory leak by manipulating
// the ath9k USB device state to cause URBs to be deallocated while
// remain_skb is still allocated.

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <linux/usbdevice_fs.h>

// Simulate the vulnerable code path
// In the ath9k driver, remain_skb is allocated in ath9k_hif_usb_rx_stream()
// when processing URBs that contain partial data spanning multiple URBs.

struct hif_dev {
    void *remain_skb;  // Cached SKB for multi-URB data
    int rx_urbs_allocated;
};

// Vulnerable function: allocates remain_skb but may not free it
// when URBs are deallocated
void ath9k_hif_usb_rx_stream(struct hif_dev *dev) {
    if (dev->remain_skb == NULL) {
        // Allocate remain_skb for partial data
        dev->remain_skb = malloc(4096);
        printf("Allocated remain_skb: %p\n", dev->remain_skb);
        // Simulate memcpy of partial data
        memcpy(dev->remain_skb, "partial_data", 12);
    } else {
        // Process the cached remain_skb
        printf("Processing remain_skb: %p\n", dev->remain_skb);
        free(dev->remain_skb);
        dev->remain_skb = NULL;
    }
}

// Trigger: deallocate URBs without processing remain_skb
void trigger_memory_leak(struct hif_dev *dev) {
    // Step 1: Receive first URB - allocates remain_skb
    ath9k_hif_usb_rx_stream(dev);
    
    // Step 2: Simulate device suspend/deinit - URBs are freed
    // but remain_skb is NOT freed (the bug)
    dev->rx_urbs_allocated = 0;
    printf("URBs deallocated, remain_skb leaked: %p\n", dev->remain_skb);
    
    // remain_skb is now leaked - it won't be freed
    // because ath9k_hif_usb_rx_stream() won't be called again
}

int main() {
    struct hif_dev dev = {0};
    
    // Trigger the leak multiple times to accumulate leaked memory
    for (int i = 0; i < 1000; i++) {
        dev.remain_skb = NULL;  // Reset for each iteration
        trigger_memory_leak(&dev);
        // In real scenario, the leaked memory accumulates
    }
    
    printf("Memory leak triggered successfully\n");
    return 0;
}

// Fix: Add explicit free of remain_skb when URBs are deallocated
// void ath9k_hif_usb_dealloc_urbs(struct hif_dev *dev) {
//     if (dev->remain_skb) {
//         kfree_skb(dev->remain_skb);
//         dev->remain_skb = NULL;
//     }
//     // ... deallocate URBs ...
// }

References

[1] CVE.org https://www.cve.org/CVERecord?id=CVE-2023-53641
[2] NVD NIST https://nvd.nist.gov/vuln/detail/CVE-2023-53641
[3] CVE Details https://www.cvedetails.com/cve/CVE-2023-53641/
[4] VulDB https://vuldb.com/cve/CVE-2023-53641
[5] https://git.kernel.org/stable/c/320d760a35273aa815d58b57e4fd9ba5279a3489
[6] https://git.kernel.org/stable/c/59073060fe0950c6ecbe12bdc06469dcac62128d
[7] https://git.kernel.org/stable/c/6719e3797ec52cd144c8a5ba8aaab36674800585
[8] https://git.kernel.org/stable/c/7654cc03eb699297130b693ec34e25f77b17c947
[9] https://git.kernel.org/stable/c/8f02d538878c9b1501f624595eb22ee4e5e0ff84
[10] https://git.kernel.org/stable/c/9b9356a3014123f0ce4b50d9278c1265173150ab
[11] https://git.kernel.org/stable/c/d9899318660791141ea6002fda5577b2c5d7386e
[12] https://git.kernel.org/stable/c/f0931fc8f4b6847c72e170d2326861c0a081d680

Raw JSON Data

JSON

{"cve": {"id": "CVE-2023-53641", "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "published": "2025-10-07T16:15:47.390", "lastModified": "2026-02-03T22:29:53.787", "vulnStatus": "Analyzed", "cveTags": [], "descriptions": [{"lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nwifi: ath9k: hif_usb: fix memory leak of remain_skbs\n\nhif_dev->remain_skb is allocated and used exclusively in\nath9k_hif_usb_rx_stream(). It is implied that an allocated remain_skb is\nprocessed and subsequently freed (in error paths) only during the next\ncall of ath9k_hif_usb_rx_stream().\n\nSo, if the urbs are deallocated between those two calls due to the device\ndeinitialization or suspend, it is possible that ath9k_hif_usb_rx_stream()\nis not called next time and the allocated remain_skb is leaked. Our local\nSyzkaller instance was able to trigger that.\n\nremain_skb makes sense when receiving two consecutive urbs which are\nlogically linked together, i.e. a specific data field from the first skb\nindicates a cached skb to be allocated, memcpy'd with some data and\nsubsequently processed in the next call to ath9k_hif_usb_rx_stream(). Urbs\ndeallocation supposedly makes that link irrelevant so we need to free the\ncached skb in those cases.\n\nFix the leak by introducing a function to explicitly free remain_skb (if\nit is not NULL) when the rx urbs have been deallocated. remain_skb is NULL\nwhen it has not been allocated at all (hif_dev struct is kzalloced) or\nwhen it has been processed in next call to ath9k_hif_usb_rx_stream().\n\nFound by Linux Verification Center (linuxtesting.org) with Syzkaller."}], "metrics": {"cvssMetricV31": [{"source": "[email protected]", "type": "Primary", "cvssData": {"version": "3.1", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H", "baseScore": 5.5, "baseSeverity": "MEDIUM", "attackVector": "LOCAL", "attackComplexity": "LOW", "privilegesRequired": "LOW", "userInteraction": "NONE", "scope": "UNCHANGED", "confidentialityImpact": "NONE", "integrityImpact": "NONE", "availabilityImpact": "HIGH"}, "exploitabilityScore": 1.8, "impactScore": 3.6}]}, "weaknesses": [{"source": "[email protected]", "type": "Primary", "description": [{"lang": "en", "value": "CWE-401"}]}], "configurations": [{"nodes": [{"operator": "OR", "negate": false, "cpeMatch": [{"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "2.6.35", "versionEndExcluding": "4.19.283", "matchCriteriaId": "0B3AD6DB-0A40-4AE7-B7CA-2BC3A8E94AD4"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "4.20", "versionEndExcluding": "5.4.243", "matchCriteriaId": "E54ACEF5-C8C1-4266-85FC-7D513FFD1DEC"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.5", "versionEndExcluding": "5.10.180", "matchCriteriaId": "78422AC3-CC89-479E-B4BC-62381D8F3564"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.11", "versionEndExcluding": "5.15.111", "matchCriteriaId": "2B9DD776-7F17-4F72-B94F-54BFCBC692DD"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "5.16", "versionEndExcluding": "6.1.28", "matchCriteriaId": "08F855F4-7188-4EE1-BD79-D4B6C7E2EF54"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.2", "versionEndExcluding": "6.2.15", "matchCriteriaId": "3844A90B-940D-46C3-8D7B-9FF63F1AFC2F"}, {"vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.3", "versionEndExcluding": "6.3.2", "matchCriteriaId": "38F6F330-91A0-4675-8B90-6F950471A7CC"}]}]}], "references": [{"url": "https://git.kernel.org/stable/c/320d760a35273aa815d58b57e4fd9ba5279a3489", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/59073060fe0950c6ecbe12bdc06469dcac62128d", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/6719e3797ec52cd144c8a5ba8aaab36674800585", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/7654cc03eb699297130b693ec34e25f77b17c947", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/8f02d538878c9b1501f624595eb22ee4e5e0ff84", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/9b9356a3014123f0ce4b50d9278c1265173150ab", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/d9899318660791141ea6002fda5577b2c5d7386e", "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "tags": ["Patch"]}, {"url": "https://git.kernel.org/stable/c/f0931fc8f4b6847c72e170d2326861c0a081d680", "source": "416baa ... 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