{"id":"CVE-2026-97953","summary":"net: stmmac: fix TX descriptor availability check for TSO traffic","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet: stmmac: fix TX descriptor availability check for TSO traffic\n\nstmmac_tso_xmit() estimates the number of free TX descriptors required by\na TSO skb as:\n\n\t(skb-\u003elen - proto_hdr_len) / TSO_MAX_BUFF_SIZE + 1\n\nwhich assumes the payload is split into TSO_MAX_BUFF_SIZE chunks. This\nunderestimates the descriptors actually consumed by stmmac_tso_allocator(),\nsince each fragment is mapped individually and so it needs at least one\ndescriptor regardless of its size. Moreover, one descriptor is used for\nthe L2/L3/L4 headers and, when the MSS changes, one more is consumed for\nthe MSS context descriptor.\nFor a highly fragmented TSO skb the check can therefore pass even when the\nring has too few free slots. stmmac_tso_allocator() then writes past the\navailable descriptors, overwriting descriptors still owned by the DMA\nengine, corrupting the TX ring.\nAdd stmmac_tso_get_num_desc() to compute the exact number of descriptors\nneeded for the header, the linear payload and each fragment, plus the MSS\ncontext descriptor when required, and use it in the availability check.","modified":"2026-09-26T03:48:41.561793705Z","published":"2026-09-25T10:23:00.758Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/97xxx/CVE-2026-97953.json"},"references":[{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"},{"type":"WEB","url":"https://git.kernel.org/stable/c/5e38d732ec67a5b1f9a56e6c73add480c4b6030a"},{"type":"WEB","url":"https://git.kernel.org/stable/c/65820fc743eae322f7f94f6a64d07861211d4b21"},{"type":"WEB","url":"https://git.kernel.org/stable/c/c28175220f808c867d5618de8ecc6dbcc815c773"},{"type":"WEB","url":"https://git.kernel.org/stable/c/ffa6d2481bc1c87f822ecd626561484e4ee24cef"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/97xxx/CVE-2026-97953.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-97953"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"f748be531d7012c456b97f66091d86b3675c5fef"},{"fixed":"ffa6d2481bc1c87f822ecd626561484e4ee24cef"},{"fixed":"c28175220f808c867d5618de8ecc6dbcc815c773"},{"fixed":"65820fc743eae322f7f94f6a64d07861211d4b21"},{"fixed":"5e38d732ec67a5b1f9a56e6c73add480c4b6030a"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-97953.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"4.7.0"},{"fixed":"6.12.111"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.53"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.2.7"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-97953.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:L/I:L/A:H"}]}