{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2026-46110", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2026-05-13T15:03:33.098Z", "datePublished": "2026-05-28T09:35:18.359Z", "dateUpdated": "2026-08-05T12:29:41.911Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T12:29:41.911Z" }, "descriptions": [ { "lang": "en", "value": "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." } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H", "baseScore": 7.5, "baseSeverity": "HIGH" }, "scenarios": [ { "lang": "en", "value": "AV:N - The vulnerable code is the Ethernet MAC driver's network receive (NAPI) path, driven entirely by incoming frames; stmmac is widely used on internet-facing routers/gateways/embedded SoCs, where a remote attacker flooding traffic drives the RX ring exhaustion and memory pressure that trigger the crash.\nAC:L - The triggering condition (RX buffer allocation failure under memory pressure plus sustained frame reception) is something the attacker can materially induce by flooding a memory-constrained device, so it is reliably reachable rather than a layout the attacker cannot influence.\nPR:N - Triggering only requires sending/flooding network frames to the interface; no authentication or local privilege is needed.\nUI:N - The crash occurs autonomously in the kernel RX path as frames are received; no victim action is required.\nS:U - The fault is a NULL dereference within the kernel itself, affecting only the kernel's own security authority with no cross-boundary impact.\nC:N - The bug is a dereference of a NULL buffer pointer with no data read back to the attacker, so there is no information disclosure.\nI:N - A NULL pointer dereference provides no memory-write or data-modification primitive.\nA:H - Dereferencing the NULL buf->page causes a kernel oops/panic, crashing the system and denying availability." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "drivers/net/ethernet/stmicro/stmmac/stmmac_main.c" ], "versions": [ { "version": "7414a28de1b3b028714859078c00a874f9feff52", "lessThan": "fdeb95b1fc7de25c9362990efb9996a8d761055c", "status": "affected", "versionType": "git" }, { "version": "779334e59850f863bf34665e0ff0b6faf126873b", "lessThan": "e1c50b273298c7cd9b08b113e7a7598b531a02f5", "status": "affected", "versionType": "git" }, { "version": "b6cb4541853c7ee512111b0e7ddf3cb66c99c137", "lessThan": "5c910f7708e3c507b037ca91ca5b09f8cfe71e65", "status": "affected", "versionType": "git" }, { "version": "b6cb4541853c7ee512111b0e7ddf3cb66c99c137", "lessThan": "4af2e62cbcda575a174acd230c3f3a208135e16d", "status": "affected", "versionType": "git" }, { "version": "b6cb4541853c7ee512111b0e7ddf3cb66c99c137", "lessThan": "950cb436165aad0f8f2cd49da3cd07677465bcde", "status": "affected", "versionType": "git" }, { "version": "b6cb4541853c7ee512111b0e7ddf3cb66c99c137", "lessThan": "0bb05e6adfa99a2ea1fee1125cc0953409f83ed8", "status": "affected", "versionType": "git" }, { "version": "b435b4573240b5530830a1a60e005c6fcfd928a0", "status": "affected", "versionType": "git" }, { "version": "6.1.64", "lessThan": "6.1.176", "status": "affected", "versionType": "semver" }, { "version": "6.6.3", "lessThan": "6.6.140", "status": "affected", "versionType": "semver" }, { "version": "6.5.13", "lessThan": "6.6", "status": "affected", "versionType": "semver" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "drivers/net/ethernet/stmicro/stmmac/stmmac_main.c" ], "versions": [ { "version": "6.7", "status": "affected" }, { "version": "0", "lessThan": "6.7", "status": "unaffected", "versionType": "semver" }, { "version": "6.1.176", "lessThanOrEqual": "6.1.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.6.140", "lessThanOrEqual": "6.6.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.12.88", "lessThanOrEqual": "6.12.*", "status": "unaffected", "versionType": "semver" }, { "version": "6.18.30", "lessThanOrEqual": "6.18.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.0.7", "lessThanOrEqual": "7.0.*", "status": "unaffected", "versionType": "semver" }, { "version": "7.1", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.1.64", "versionEndExcluding": "6.1.176" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.6.3", "versionEndExcluding": "6.6.140" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.7", "versionEndExcluding": "6.12.88" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.7", "versionEndExcluding": "6.18.30" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.7", "versionEndExcluding": "7.0.7" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.7", "versionEndExcluding": "7.1" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "6.5.13" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/fdeb95b1fc7de25c9362990efb9996a8d761055c" }, { "url": "https://git.kernel.org/stable/c/e1c50b273298c7cd9b08b113e7a7598b531a02f5" }, { "url": "https://git.kernel.org/stable/c/5c910f7708e3c507b037ca91ca5b09f8cfe71e65" }, { "url": "https://git.kernel.org/stable/c/4af2e62cbcda575a174acd230c3f3a208135e16d" }, { "url": "https://git.kernel.org/stable/c/950cb436165aad0f8f2cd49da3cd07677465bcde" }, { "url": "https://git.kernel.org/stable/c/0bb05e6adfa99a2ea1fee1125cc0953409f83ed8" } ], "title": "net: stmmac: Prevent NULL deref when RX memory exhausted", "x_generator": { "engine": "bippy-1.2.0" } } } }