{"id":"CVE-2026-98116","summary":"ALSA: pcm: Serialize PCM mmap with buffer reallocation to fix page UAF","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nALSA: pcm: Serialize PCM mmap with buffer reallocation to fix page UAF\n\nsnd_pcm_hw_params() and snd_pcm_hw_free() guard buffer reallocation\nwith an mmap_count check performed under the PCM stream lock, but the\nlock is released long before the buffer is actually freed:\nsnd_pcm_sync_stop(), constraint refinement and do_free_pages() all\nhappen in between.  snd_pcm_mmap_data(), on the other hand, takes no\nlock at all: it validates against the old buffer's state and\ndma_bytes, remaps its pages into the VMA, and only then increments\nmmap_count.\n\nA concurrent mmap() can therefore slip in between the check and the\nfree.  remap_pfn_range() installs writable PTEs for the old buffer's\npages without taking page references, and the subsequent\ndo_free_pages() returns those pages to the page allocator while the\nVMA still maps them.  This leaves a stale, writable mapping of freed\npages: a page-level use-after-free that can be leveraged for local\nprivilege escalation.\n\nMake snd_pcm_mmap_data() participate in the buffer-access scheme\nintroduced for hw_params/hw_free: acquire runtime-\u003ebuffer_accessing\nbefore validating and remapping, and release it afterwards.  Buffer\nreallocation already fails with -EBUSY while accessors are active,\nand the mmap side now fails with -EBUSY while a reallocation is in\nprogress, so the validate/remap sequence and the check/free sequence\ncan no longer interleave.\n\nA reproducer that turns this race into a stale writable mapping of\nthe freed DMA buffer pages is available on request.","modified":"2026-11-13T04:07:26.828287952Z","published":"2026-09-25T10:36:01.723Z","related":["SUSE-SU-2026:24550-1","SUSE-SU-2026:24619-1","SUSE-SU-2026:24643-1","SUSE-SU-2026:24648-1","SUSE-SU-2026:24651-1","SUSE-SU-2026:24662-1","SUSE-SU-2026:5091-1","SUSE-SU-2026:5121-1","openSUSE-SU-2026:12074-1"],"database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98116.json","cna_assigner":"Linux"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/8c1882dfee8f404d118020664b73eb4592172226"},{"type":"WEB","url":"https://git.kernel.org/stable/c/9857a75714bb5df4781e4d8b1a1753b1e17bf07a"},{"type":"WEB","url":"https://git.kernel.org/stable/c/9b110a9dcecc59516c77cb3c0caf1f492f75df2d"},{"type":"WEB","url":"https://git.kernel.org/stable/c/cbadf2575d25e7dcc0d4da2717817ae569fbc99b"},{"type":"WEB","url":"https://git.kernel.org/stable/c/cbc7ec97601d09b74e05e44470fa6b0bcdabf3f5"},{"type":"WEB","url":"https://git.kernel.org/stable/c/e6cdd2a0470d64073349a970dc1691433804b271"},{"type":"WEB","url":"https://git.kernel.org/stable/c/fd137bf8149bc6460f9b7b1fc292025da04cb9ee"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98116.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-98116"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"33061d0fba51d2bf70a2ef9645f703c33fe8e438"},{"fixed":"e6cdd2a0470d64073349a970dc1691433804b271"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"92ee3c60ec9fe64404dc035e7c41277d74aa26cb"},{"fixed":"9857a75714bb5df4781e4d8b1a1753b1e17bf07a"},{"fixed":"cbadf2575d25e7dcc0d4da2717817ae569fbc99b"},{"fixed":"cbc7ec97601d09b74e05e44470fa6b0bcdabf3f5"},{"fixed":"fd137bf8149bc6460f9b7b1fc292025da04cb9ee"},{"fixed":"8c1882dfee8f404d118020664b73eb4592172226"},{"fixed":"9b110a9dcecc59516c77cb3c0caf1f492f75df2d"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"a42aa926843acca96c0dfbde2e835b8137f2f092"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"9cb6c40a6ebe4a0cfc9d6a181958211682cffea9"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"fbeb492694ce0441053de57699e1e2b7bc148a69"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"0f6947f5f5208f6ebd4d76a82a4757e2839a23f8"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"0090c13cbbdffd7da079ac56f80373a9a1be0bf8"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"1bbf82d9f961414d6c76a08f7f843ea068e0ab7b"}]}],"versions":["v5.15.221","v5.15.220","v5.15.219","v5.15.218","v5.15.217","v5.15.216","v5.15.215","v5.15.214","v5.15.213","v5.15.212","v5.15.211","v5.15.210","v5.15.209","v5.15.208","v5.15.207","v5.15.206","v5.15.205","v5.15.204","v5.15.203","v5.15.202","v5.15.201","v5.15.200","v5.15.199","v5.15.198","v5.15.197","v5.15.196","v5.15.195","v5.15.194","v5.15.193","v5.15.192","v5.15.191","v5.15.190","v5.15.189","v5.15.188","v5.15.187","v5.15.186","v5.15.185","v5.15.184","v5.15.183","v5.15.182","v5.15.181","v5.15.180","v5.15.179","v5.15.178","v5.15.177","v5.15.176","v5.15.175","v5.15.174","v5.15.173","v5.15.172","v5.15.171","v5.15.170","v5.15.169","v5.15.168","v5.15.167","v5.15.166","v5.15.165","v5.15.164","v5.15.163","v5.15.162","v5.15.161","v5.15.160","v5.15.159","v5.15.158","v5.15.157","v5.15.156","v5.15.155","v5.15.154","v5.15.153","v5.15.152","v5.15.151","v5.15.150","v5.15.149","v5.15.148","v5.15.147","v5.15.146","v5.15.145","v5.15.144","v5.15.143","v5.15.142","v5.15.141","v5.15.140","v5.15.139","v5.15.138","v5.15.137","v5.15.136","v5.15.135","v5.15.134","v5.15.133","v5.15.132","v5.15.131","v5.15.130","v5.15.129","v5.15.128","v5.15.127","v5.15.126","v5.15.125","v5.15.124","v5.15.123","v5.15.122","v5.15.121","v5.15.120","v5.15.119","v5.15.118","v5.15.117","v5.15.116","v5.15.115","v5.15.114","v5.15.113","v5.15.112","v5.15.111","v5.15.110","v5.15.109","v5.15.108","v5.15.107","v5.15.106","v5.15.105","v5.15.104","v5.15.103","v5.15.102","v5.15.101","v5.15.100","v5.15.99","v5.15.98","v5.15.97","v5.15.96","v5.15.95","v5.15.94","v5.15.93","v5.15.92","v5.15.91","v5.15.90","v5.15.89","v5.15.88","v5.15.87","v5.15.86","v5.15.85","v5.15.84","v5.15.83","v5.15.82","v5.15.81","v5.15.80","v5.15.79","v5.15.78","v5.15.77","v5.15.76","v5.15.75","v5.15.74","v5.15.73","v5.15.72","v5.15.71","v5.15.70","v5.15.69","v5.15.68","v5.15.67","v5.15.66","v5.15.65","v5.15.64","v5.15.63","v5.15.62","v5.15.61"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