{"cve":"CVE-2022-49648","nvd":{"published":"2025-02-26T07:01:39.957","modified":"2026-06-17T05:18:44.717","status":"Modified","description":"In the Linux kernel, the following vulnerability has been resolved:\n\ntracing/histograms: Fix memory leak problem\n\nThis reverts commit 46bbe5c671e06f070428b9be142cc4ee5cedebac.\n\nAs commit 46bbe5c671e0 (\"tracing: fix double free\") said, the\n\"double free\" problem reported by clang static analyzer is:\n  > In parse_var_defs() if there is a problem allocating\n  > var_defs.expr, the earlier var_defs.name is freed.\n  > This free is duplicated by free_var_defs() which frees\n  > the rest of the list.\n\nHowever, if there is a problem allocating N-th var_defs.expr:\n  + in parse_var_defs(), the freed 'earlier var_defs.name' is\n    actually the N-th var_defs.name;\n  + then in free_var_defs(), the names from 0th to (N-1)-th are freed;\n\n                        IF ALLOCATING PROBLEM HAPPENED HERE!!! -+\n                                                                 \\\n                                                                  |\n          0th           1th                 (N-1)-th      N-th    V\n          +-------------+-------------+-----+-------------+-----------\nvar_defs: | name | expr | name | expr | ... | name | expr | name | ///\n          +-------------+-------------+-----+-------------+-----------\n\nThese two frees don't act on same name, so there was no \"double free\"\nproblem before. Conversely, after that commit, we get a \"memory leak\"\nproblem because the above \"N-th var_defs.name\" is not freed.\n\nIf enable CONFIG_DEBUG_KMEMLEAK and inject a fault at where the N-th\nvar_defs.expr allocated, then execute on shell like:\n  $ echo 'hist:key=call_site:val=$v1,$v2:v1=bytes_req,v2=bytes_alloc' > \\\n/sys/kernel/debug/tracing/events/kmem/kmalloc/trigger\n\nThen kmemleak reports:\n  unreferenced object 0xffff8fb100ef3518 (size 8):\n    comm \"bash\", pid 196, jiffies 4295681690 (age 28.538s)\n    hex dump (first 8 bytes):\n      76 31 00 00 b1 8f ff ff                          v1......\n    backtrace:\n      [<0000000038fe4895>] kstrdup+0x2d/0x60\n      [<00000000c99c049a>] event_hist_trigger_parse+0x206f/0x20e0\n      [<00000000ae70d2cc>] trigger_process_regex+0xc0/0x110\n      [<0000000066737a4c>] event_trigger_write+0x75/0xd0\n      [<000000007341e40c>] vfs_write+0xbb/0x2a0\n      [<0000000087fde4c2>] ksys_write+0x59/0xd0\n      [<00000000581e9cdf>] do_syscall_64+0x3a/0x80\n      [<00000000cf3b065c>] entry_SYSCALL_64_after_hwframe+0x46/0xb0","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","score":5.5},"cwes":["CWE-401"],"references":["https://git.kernel.org/stable/c/22eeff55679d9e7c0f768c79bfbd83e2f8142d89","https://git.kernel.org/stable/c/4d453eb5e1eec89971aa5b3262857ee26cfdffd3","https://git.kernel.org/stable/c/78a1400c42ee11197eb1f0f85ba51df9a4fdfff0","https://git.kernel.org/stable/c/7edc3945bdce9c39198a10d6129377a5c53559c2","https://git.kernel.org/stable/c/eb622d5580b9e2ff694f62da6410618bd73853cb"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-19T21:59:48.811064707+00:00"},"epss":{"cve":"CVE-2022-49648","score":0.00272,"percentile":0.19586,"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."]}