{"cve":"CVE-2024-35798","nvd":{"published":"2024-05-17T14:15:12.170","modified":"2026-08-04T11:17:54.100","status":"Modified","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: fix race in read_extent_buffer_pages()\n\nThere are reports from tree-checker that detects corrupted nodes,\nwithout any obvious pattern so possibly an overwrite in memory.\nAfter some debugging it turns out there's a race when reading an extent\nbuffer the uptodate status can be missed.\n\nTo prevent concurrent reads for the same extent buffer,\nread_extent_buffer_pages() performs these checks:\n\n    /* (1) */\n    if (test_bit(EXTENT_BUFFER_UPTODATE, &eb->bflags))\n        return 0;\n\n    /* (2) */\n    if (test_and_set_bit(EXTENT_BUFFER_READING, &eb->bflags))\n        goto done;\n\nAt this point, it seems safe to start the actual read operation. Once\nthat completes, end_bbio_meta_read() does\n\n    /* (3) */\n    set_extent_buffer_uptodate(eb);\n\n    /* (4) */\n    clear_bit(EXTENT_BUFFER_READING, &eb->bflags);\n\nNormally, this is enough to ensure only one read happens, and all other\ncallers wait for it to finish before returning.  Unfortunately, there is\na racey interleaving:\n\n    Thread A | Thread B | Thread C\n    ---------+----------+---------\n       (1)   |          |\n             |    (1)   |\n       (2)   |          |\n       (3)   |          |\n       (4)   |          |\n             |    (2)   |\n             |          |    (1)\n\nWhen this happens, thread B kicks of an unnecessary read. Worse, thread\nC will see UPTODATE set and return immediately, while the read from\nthread B is still in progress.  This race could result in tree-checker\nerrors like this as the extent buffer is concurrently modified:\n\n    BTRFS critical (device dm-0): corrupted node, root=256\n    block=8550954455682405139 owner mismatch, have 11858205567642294356\n    expect [256, 18446744073709551360]\n\nFix it by testing UPTODATE again after setting the READING bit, and if\nit's been set, skip the unnecessary read.\n\n[ minor update of changelog ]","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H","score":4.7},"cwes":["CWE-362"],"references":["https://git.kernel.org/stable/c/0427c8ef8bbb7f304de42ef51d69c960e165e052","https://git.kernel.org/stable/c/2885d54af2c2e1d910e20d5c8045bae40e02fbc1","https://git.kernel.org/stable/c/3a25878a3378adce5d846300c9570f15aa7f7a80","https://git.kernel.org/stable/c/ef1e68236b9153c27cb7cf29ead0c532870d4215","https://git.kernel.org/stable/c/0427c8ef8bbb7f304de42ef51d69c960e165e052"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-19T21:50:30.954589733+00:00"},"epss":{"cve":"CVE-2024-35798","score":0.00179,"percentile":0.07438,"date":"2026-10-31"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}