{"id":"CVE-2026-98127","summary":"smb/client: validate new EOF for insert range","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nsmb/client: validate new EOF for insert range\n\nsmb3_insert_range() does not check if the new file size\n(i_size + len) is valid. This allows FALLOC_FL_INSERT_RANGE to bypass\nRLIMIT_FSIZE, exceed s_maxbytes, or produce a size outside the loff_t\nrange.\n\nUse check_add_overflow() to calculate the new EOF. Validate it with\ninode_newsize_ok() before modifying the file.\n\nReproducer, using a file on a CIFS mount:\n\n\tbash -c '\n\t\tFILE=/mnt/cifs/repro\n\n\t\ttrap \"\" SIGXFSZ\n\t\tulimit -f 3072\t\t# RLIMIT_FSIZE = 3 MiB\n\n\t\t# A regular write is stopped at 3 MiB.\n\t\tdd if=/dev/zero of=\"$FILE\" bs=1M count=4 status=none\n\t\tstat -c \"size after write: %s\" \"$FILE\"\n\n\t\t# Insert 2 MiB into a 2 MiB file.\n\t\ttruncate -s 2M \"$FILE\"\n\t\tfallocate -i -o 0 -l 2M \"$FILE\"\n\t\tstat -c \"size after insert: %s\" \"$FILE\"\n\t'\n\nBefore this change, the regular write stops at the 3 MiB limit, but\ninsert range grows the file to 4 MiB:\n\n\tdd: error writing '/mnt/cifs/repro': File too large\n\tsize after write: 3145728\n\tsize after insert: 4194304\n\nAfter this change, insert range also fails at the limit and leaves the\n2 MiB file unchanged:\n\n\tdd: error writing '/mnt/cifs/repro': File too large\n\tsize after write: 3145728\n\tfallocate: fallocate failed: File too large\n\tsize after insert: 2097152","modified":"2026-09-26T03:48:32.733398978Z","published":"2026-09-25T10:36:08.406Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98127.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/1519dc88c87f5346dae0464d7d6da1b6bf1f6e8e"},{"type":"WEB","url":"https://git.kernel.org/stable/c/7c2c69045aa76ccaa7f16f1478eb312130ce4951"},{"type":"WEB","url":"https://git.kernel.org/stable/c/bc7602b9082ef195d913c4c16fa9853dd262333e"},{"type":"WEB","url":"https://git.kernel.org/stable/c/f8cbfe3a3fcee7d991fd223f660f3e5df13221cf"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/98xxx/CVE-2026-98127.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-98127"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"7fe6fe95b936084dce6eedcc2cccadf96eafae73"},{"fixed":"7c2c69045aa76ccaa7f16f1478eb312130ce4951"},{"fixed":"bc7602b9082ef195d913c4c16fa9853dd262333e"},{"fixed":"f8cbfe3a3fcee7d991fd223f660f3e5df13221cf"},{"fixed":"1519dc88c87f5346dae0464d7d6da1b6bf1f6e8e"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-98127.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"5.13.0"},{"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-2026-98127.json"}}],"schema_version":"1.9.0"}