ghsa-4fpg-2m6r-6cc4
Vulnerability from github
In the Linux kernel, the following vulnerability has been resolved:
net: ethernet: oa_tc6: fix tx skb race condition between reference pointers
There are two skb pointers to manage tx skb's enqueued from n/w stack. waiting_tx_skb pointer points to the tx skb which needs to be processed and ongoing_tx_skb pointer points to the tx skb which is being processed.
SPI thread prepares the tx data chunks from the tx skb pointed by the ongoing_tx_skb pointer. When the tx skb pointed by the ongoing_tx_skb is processed, the tx skb pointed by the waiting_tx_skb is assigned to ongoing_tx_skb and the waiting_tx_skb pointer is assigned with NULL. Whenever there is a new tx skb from n/w stack, it will be assigned to waiting_tx_skb pointer if it is NULL. Enqueuing and processing of a tx skb handled in two different threads.
Consider a scenario where the SPI thread processed an ongoing_tx_skb and it moves next tx skb from waiting_tx_skb pointer to ongoing_tx_skb pointer without doing any NULL check. At this time, if the waiting_tx_skb pointer is NULL then ongoing_tx_skb pointer is also assigned with NULL. After that, if a new tx skb is assigned to waiting_tx_skb pointer by the n/w stack and there is a chance to overwrite the tx skb pointer with NULL in the SPI thread. Finally one of the tx skb will be left as unhandled, resulting packet missing and memory leak.
- Consider the below scenario where the TXC reported from the previous transfer is 10 and ongoing_tx_skb holds an tx ethernet frame which can be transported in 20 TXCs and waiting_tx_skb is still NULL. tx_credits = 10; / 21 are filled in the previous transfer / ongoing_tx_skb = 20; waiting_tx_skb = NULL; / Still NULL /
- So, (tc6->ongoing_tx_skb || tc6->waiting_tx_skb) becomes true.
- After oa_tc6_prepare_spi_tx_buf_for_tx_skbs() ongoing_tx_skb = 10; waiting_tx_skb = NULL; / Still NULL /
- Perform SPI transfer.
- Process SPI rx buffer to get the TXC from footers.
- Now let's assume previously filled 21 TXCs are freed so we are good to transport the next remaining 10 tx chunks from ongoing_tx_skb. tx_credits = 21; ongoing_tx_skb = 10; waiting_tx_skb = NULL;
- So, (tc6->ongoing_tx_skb || tc6->waiting_tx_skb) becomes true again.
-
In the oa_tc6_prepare_spi_tx_buf_for_tx_skbs() ongoing_tx_skb = NULL; waiting_tx_skb = NULL;
-
Now the below bad case might happen,
Thread1 (oa_tc6_start_xmit) Thread2 (oa_tc6_spi_thread_handler)
- if waiting_tx_skb is NULL - if ongoing_tx_skb is NULL - ongoing_tx_skb = waiting_tx_skb
- waiting_tx_skb = skb - waiting_tx_skb = NULL ... - ongoing_tx_skb = NULL
- if waiting_tx_skb is NULL
- waiting_tx_skb = skb
To overcome the above issue, protect the moving of tx skb reference from waiting_tx_skb pointer to ongoing_tx_skb pointer and assigning new tx skb to waiting_tx_skb pointer, so that the other thread can't access the waiting_tx_skb pointer until the current thread completes moving the tx skb reference safely.
{
"affected": [],
"aliases": [
"CVE-2024-56788"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-01-11T13:15:29Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: ethernet: oa_tc6: fix tx skb race condition between reference pointers\n\nThere are two skb pointers to manage tx skb\u0027s enqueued from n/w stack.\nwaiting_tx_skb pointer points to the tx skb which needs to be processed\nand ongoing_tx_skb pointer points to the tx skb which is being processed.\n\nSPI thread prepares the tx data chunks from the tx skb pointed by the\nongoing_tx_skb pointer. When the tx skb pointed by the ongoing_tx_skb is\nprocessed, the tx skb pointed by the waiting_tx_skb is assigned to\nongoing_tx_skb and the waiting_tx_skb pointer is assigned with NULL.\nWhenever there is a new tx skb from n/w stack, it will be assigned to\nwaiting_tx_skb pointer if it is NULL. Enqueuing and processing of a tx skb\nhandled in two different threads.\n\nConsider a scenario where the SPI thread processed an ongoing_tx_skb and\nit moves next tx skb from waiting_tx_skb pointer to ongoing_tx_skb pointer\nwithout doing any NULL check. At this time, if the waiting_tx_skb pointer\nis NULL then ongoing_tx_skb pointer is also assigned with NULL. After\nthat, if a new tx skb is assigned to waiting_tx_skb pointer by the n/w\nstack and there is a chance to overwrite the tx skb pointer with NULL in\nthe SPI thread. Finally one of the tx skb will be left as unhandled,\nresulting packet missing and memory leak.\n\n- Consider the below scenario where the TXC reported from the previous\ntransfer is 10 and ongoing_tx_skb holds an tx ethernet frame which can be\ntransported in 20 TXCs and waiting_tx_skb is still NULL.\n\ttx_credits = 10; /* 21 are filled in the previous transfer */\n\tongoing_tx_skb = 20;\n\twaiting_tx_skb = NULL; /* Still NULL */\n- So, (tc6-\u003eongoing_tx_skb || tc6-\u003ewaiting_tx_skb) becomes true.\n- After oa_tc6_prepare_spi_tx_buf_for_tx_skbs()\n\tongoing_tx_skb = 10;\n\twaiting_tx_skb = NULL; /* Still NULL */\n- Perform SPI transfer.\n- Process SPI rx buffer to get the TXC from footers.\n- Now let\u0027s assume previously filled 21 TXCs are freed so we are good to\ntransport the next remaining 10 tx chunks from ongoing_tx_skb.\n\ttx_credits = 21;\n\tongoing_tx_skb = 10;\n\twaiting_tx_skb = NULL;\n- So, (tc6-\u003eongoing_tx_skb || tc6-\u003ewaiting_tx_skb) becomes true again.\n- In the oa_tc6_prepare_spi_tx_buf_for_tx_skbs()\n\tongoing_tx_skb = NULL;\n\twaiting_tx_skb = NULL;\n\n- Now the below bad case might happen,\n\nThread1 (oa_tc6_start_xmit)\tThread2 (oa_tc6_spi_thread_handler)\n---------------------------\t-----------------------------------\n- if waiting_tx_skb is NULL\n\t\t\t\t- if ongoing_tx_skb is NULL\n\t\t\t\t- ongoing_tx_skb = waiting_tx_skb\n- waiting_tx_skb = skb\n\t\t\t\t- waiting_tx_skb = NULL\n\t\t\t\t...\n\t\t\t\t- ongoing_tx_skb = NULL\n- if waiting_tx_skb is NULL\n- waiting_tx_skb = skb\n\nTo overcome the above issue, protect the moving of tx skb reference from\nwaiting_tx_skb pointer to ongoing_tx_skb pointer and assigning new tx skb\nto waiting_tx_skb pointer, so that the other thread can\u0027t access the\nwaiting_tx_skb pointer until the current thread completes moving the tx\nskb reference safely.",
"id": "GHSA-4fpg-2m6r-6cc4",
"modified": "2025-01-11T15:30:29Z",
"published": "2025-01-11T15:30:29Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-56788"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/1f2eb6c32bae04b375bb7a0aedbeefb6dbbcb775"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/e592b5110b3e9393881b0a019d86832bbf71a47f"
}
],
"schema_version": "1.4.0",
"severity": []
}
Sightings
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