{"id":"DEBIAN-CVE-2024-56788","details":"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. \ttx_credits = 10; /* 21 are filled in the previous transfer */ \tongoing_tx_skb = 20; \twaiting_tx_skb = NULL; /* Still NULL */ - So, (tc6-\u003eongoing_tx_skb || tc6-\u003ewaiting_tx_skb) becomes true. - After oa_tc6_prepare_spi_tx_buf_for_tx_skbs() \tongoing_tx_skb = 10; \twaiting_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. \ttx_credits = 21; \tongoing_tx_skb = 10; \twaiting_tx_skb = NULL; - So, (tc6-\u003eongoing_tx_skb || tc6-\u003ewaiting_tx_skb) becomes true again. - In the oa_tc6_prepare_spi_tx_buf_for_tx_skbs() \tongoing_tx_skb = NULL; \twaiting_tx_skb = NULL;  - Now the below bad case might happen,  Thread1 (oa_tc6_start_xmit)\tThread2 (oa_tc6_spi_thread_handler) ---------------------------\t----------------------------------- - if waiting_tx_skb is NULL \t\t\t\t- if ongoing_tx_skb is NULL \t\t\t\t- ongoing_tx_skb = waiting_tx_skb - waiting_tx_skb = skb \t\t\t\t- waiting_tx_skb = NULL \t\t\t\t... \t\t\t\t- 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.","modified":"2026-09-15T09:03:16.185392773Z","published":"2025-01-11T13:15:29.090Z","upstream":["CVE-2024-56788"],"references":[{"type":"ADVISORY","url":"https://security-tracker.debian.org/tracker/CVE-2024-56788"}],"affected":[{"package":{"name":"linux","ecosystem":"Debian:13","purl":"pkg:deb/debian/linux?arch=source&distro=trixie"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.12.8-1"}]}],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2024-56788.json"}},{"package":{"name":"linux","ecosystem":"Debian:14","purl":"pkg:deb/debian/linux?arch=source&distro=forky"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"6.12.8-1"}]}],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2024-56788.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H"}]}