{"id":"CVE-2026-46110","revision":"017b5f1c283a4b278ef0fc58ce40c596","records":[{"revision":"017b5f1c283a4b278ef0fc58ce40c596","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-46110","aliases":[],"title":"net: stmmac: Prevent NULL deref when RX memory exhausted","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: stmmac: Prevent NULL deref when RX memory exhausted\n\nThe CPU receives frames from the MAC through conventional DMA: the CPU\nallocates buffers for the MAC, then the MAC fills them and returns\nownership to the CPU. For each hardware RX queue, the CPU and MAC\ncoordinate through a shared ring array of DMA descriptors: one\ndescriptor per DMA buffer. Each descriptor includes the buffer's\nphysical address and a status flag (\"OWN\") indicating which side owns\nthe buffer: OWN=0 for CPU, OWN=1 for MAC. The CPU is only allowed to set\nthe flag and the MAC is only allowed to clear it, and both must move\nthrough the ring in sequence: thus the ring is used for both\n\"submissions\" and \"completions.\"\n\nIn the stmmac driver, stmmac_rx() bookmarks its position in the ring\nwith the `cur_rx` index. The main receive loop in that function checks\nfor rx_descs[cur_rx].own=0, gives the corresponding buffer to the\nnetwork stack (NULLing the pointer), and increments `cur_rx` modulo the\nring size. After the loop exits, stmmac_rx_refill(), which bookmarks its\nposition with `dirty_rx`, allocates fresh buffers and rearms the\ndescriptors (setting OWN=1). If it fails any allocation, it simply stops\nearly (leaving OWN=0) and will retry where it left off when next called.\n\nThis means descriptors have a three-stage lifecycle (terms my own):\n- `empty` (OWN=1, buffer valid)\n- `full` (OWN=0, buffer valid and populated)\n- `dirty` (OWN=0, buffer NULL)\n\nBut because stmmac_rx() only checks OWN, it confuses `full`/`dirty`. In\nthe past (see 'Fixes:'), there was a bug where the loop could cycle\n`cur_rx` all the way back to the first descriptor it dirtied, resulting\nin a NULL dereference when mistaken for `full`. The aforementioned\ncommit resolved that *specific* failure by capping the loop's iteration\nlimit at `dma_rx_size - 1`, but this is only a partial fix: if the\nprevious stmmac_rx_refill() didn't complete, then there are leftover\n`dirty` descriptors that the loop might encounter without needing to\ncycle fully around. The current code therefore panics (see 'Closes:')\nwhen stmmac_rx_refill() is memory-starved long enough for `cur_rx` to\ncatch up to `dirty_rx`.\n\nFix this by explicitly checking, before advancing `cur_rx`, if the next\nentry is dirty; exit the loop if so. This prevents processing of the\nfinal, used descriptor until stmmac_rx_refill() succeeds, but\nfully prevents the `cur_rx == dirty_rx` ambiguity as the previous bugfix\nintended: so remove the clamp as well. Since stmmac_rx_zc() is a\ncopy-paste-and-tweak of stmmac_rx() and the code structure is identical,\nany fix to stmmac_rx() will also need a corresponding fix for\nstmmac_rx_zc(). Therefore, apply the same check there.\n\nIn stmmac_rx() (not stmmac_rx_zc()), a related bug remains: after the\nMAC sets OWN=0 on the final descriptor, it will be unable to send any\nfurther DMA-complete IRQs until it's given more `empty` descriptors.\nCurrently, the driver simply *hopes* that the next stmmac_rx_refill()\nsucceeds, risking an indefinite stall of the receive process if not. But\nthis is not a regression, so it can be addressed in a future change.","state":0,"publishedAt":"2026-05-28T09:35:18.359+00:00","modifiedAt":"2026-10-15T01:20:33.839+00:00","affected":[{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"product\": \"Linux\",\n                    \"vendor\": \"Linux\",\n                    \"defaultStatus\": \"unaffected\",\n                    \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n                    \"programFiles\": [\n                        \"drivers/net/ethernet/stmicro/stmmac/stmmac_main.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"7414a28de1b3b028714859078c00a874f9feff52\",\n                            \"lessThan\": \"fdeb95b1fc7de25c9362990efb9996a8d761055c\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"779334e59850f863bf34665e0ff0b6faf126873b\",\n                            \"lessThan\": \"e1c50b273298c7cd9b08b113e7a7598b531a02f5\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"b6cb4541853c7ee512111b0e7ddf3cb66c99c137\",\n                            \"lessThan\": \"5c910f7708e3c507b037ca91ca5b09f8cfe71e65\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"b6cb4541853c7ee512111b0e7ddf3cb66c99c137\",\n                            \"lessThan\": \"4af2e62cbcda575a174acd230c3f3a208135e16d\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"b6cb4541853c7ee512111b0e7ddf3cb66c99c137\",\n                            \"lessThan\": \"950cb436165aad0f8f2cd49da3cd07677465bcde\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"b6cb4541853c7ee512111b0e7ddf3cb66c99c137\",\n                            \"lessThan\": \"0bb05e6adfa99a2ea1fee1125cc0953409f83ed8\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"b435b4573240b5530830a1a60e005c6fcfd928a0\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"6.1.64\",\n                            \"lessThan\": \"6.1.176\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.6.3\",\n                            \"lessThan\": \"6.6.140\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.5.13\",\n                            \"lessThan\": \"6.6\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"semver\"\n                        }\n                    ]\n                }"},{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"product\": \"Linux\",\n                    \"vendor\": \"Linux\",\n                    \"defaultStatus\": \"affected\",\n                    \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n                    \"programFiles\": [\n                        \"drivers/net/ethernet/stmicro/stmmac/stmmac_main.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"6.7\",\n                            \"status\": \"affected\"\n                        },\n                        {\n                            \"version\": \"0\",\n                            \"lessThan\": \"6.7\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.1.176\",\n                            \"lessThanOrEqual\": \"6.1.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.6.140\",\n                            \"lessThanOrEqual\": \"6.6.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.12.88\",\n                            \"lessThanOrEqual\": \"6.12.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.18.30\",\n                            \"lessThanOrEqual\": \"6.18.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.0.7\",\n                            \"lessThanOrEqual\": \"7.0.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.1\",\n                            \"lessThanOrEqual\": \"*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"original_commit_for_fix\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","score":7.5,"severity":"HIGH"}],"references":["https://git.kernel.org/stable/c/fdeb95b1fc7de25c9362990efb9996a8d761055c","https://git.kernel.org/stable/c/e1c50b273298c7cd9b08b113e7a7598b531a02f5","https://git.kernel.org/stable/c/5c910f7708e3c507b037ca91ca5b09f8cfe71e65","https://git.kernel.org/stable/c/4af2e62cbcda575a174acd230c3f3a208135e16d","https://git.kernel.org/stable/c/950cb436165aad0f8f2cd49da3cd07677465bcde","https://git.kernel.org/stable/c/0bb05e6adfa99a2ea1fee1125cc0953409f83ed8"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-46110","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-46110","identifiers":["CVE-2026-46110"]},"retained":false,"historicalAffected":[]}],"coverage":[]}