ghsa-7rcj-vmjp-fwmv
Vulnerability from github
In the Linux kernel, the following vulnerability has been resolved:
tracing/histograms: Fix memory leak problem
This reverts commit 46bbe5c671e06f070428b9be142cc4ee5cedebac.
As commit 46bbe5c671e0 ("tracing: fix double free") said, the "double free" problem reported by clang static analyzer is:
In parse_var_defs() if there is a problem allocating var_defs.expr, the earlier var_defs.name is freed. This free is duplicated by free_var_defs() which frees the rest of the list.
However, if there is a problem allocating N-th var_defs.expr: + in parse_var_defs(), the freed 'earlier var_defs.name' is actually the N-th var_defs.name; + then in free_var_defs(), the names from 0th to (N-1)-th are freed;
IF ALLOCATING PROBLEM HAPPENED HERE!!! -+
\
|
0th 1th (N-1)-th N-th V
+-------------+-------------+-----+-------------+-----------
var_defs: | name | expr | name | expr | ... | name | expr | name | /// +-------------+-------------+-----+-------------+-----------
These two frees don't act on same name, so there was no "double free" problem before. Conversely, after that commit, we get a "memory leak" problem because the above "N-th var_defs.name" is not freed.
If enable CONFIG_DEBUG_KMEMLEAK and inject a fault at where the N-th var_defs.expr allocated, then execute on shell like: $ echo 'hist:key=call_site:val=$v1,$v2:v1=bytes_req,v2=bytes_alloc' > \ /sys/kernel/debug/tracing/events/kmem/kmalloc/trigger
Then kmemleak reports: unreferenced object 0xffff8fb100ef3518 (size 8): comm "bash", pid 196, jiffies 4295681690 (age 28.538s) hex dump (first 8 bytes): 76 31 00 00 b1 8f ff ff v1...... backtrace: [<0000000038fe4895>] kstrdup+0x2d/0x60 [<00000000c99c049a>] event_hist_trigger_parse+0x206f/0x20e0 [<00000000ae70d2cc>] trigger_process_regex+0xc0/0x110 [<0000000066737a4c>] event_trigger_write+0x75/0xd0 [<000000007341e40c>] vfs_write+0xbb/0x2a0 [<0000000087fde4c2>] ksys_write+0x59/0xd0 [<00000000581e9cdf>] do_syscall_64+0x3a/0x80 [<00000000cf3b065c>] entry_SYSCALL_64_after_hwframe+0x46/0xb0
{
"affected": [],
"aliases": [
"CVE-2022-49648"
],
"database_specific": {
"cwe_ids": [
"CWE-401"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-02-26T07:01:39Z",
"severity": "MODERATE"
},
"details": "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 \u003e In parse_var_defs() if there is a problem allocating\n \u003e var_defs.expr, the earlier var_defs.name is freed.\n \u003e This free is duplicated by free_var_defs() which frees\n \u003e 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 \u0027earlier var_defs.name\u0027 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\u0027t 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 \u0027hist:key=call_site:val=$v1,$v2:v1=bytes_req,v2=bytes_alloc\u0027 \u003e \\\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 [\u003c0000000038fe4895\u003e] kstrdup+0x2d/0x60\n [\u003c00000000c99c049a\u003e] event_hist_trigger_parse+0x206f/0x20e0\n [\u003c00000000ae70d2cc\u003e] trigger_process_regex+0xc0/0x110\n [\u003c0000000066737a4c\u003e] event_trigger_write+0x75/0xd0\n [\u003c000000007341e40c\u003e] vfs_write+0xbb/0x2a0\n [\u003c0000000087fde4c2\u003e] ksys_write+0x59/0xd0\n [\u003c00000000581e9cdf\u003e] do_syscall_64+0x3a/0x80\n [\u003c00000000cf3b065c\u003e] entry_SYSCALL_64_after_hwframe+0x46/0xb0",
"id": "GHSA-7rcj-vmjp-fwmv",
"modified": "2025-03-12T00:31:48Z",
"published": "2025-03-12T00:31:48Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2022-49648"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/22eeff55679d9e7c0f768c79bfbd83e2f8142d89"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/4d453eb5e1eec89971aa5b3262857ee26cfdffd3"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/78a1400c42ee11197eb1f0f85ba51df9a4fdfff0"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/7edc3945bdce9c39198a10d6129377a5c53559c2"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/eb622d5580b9e2ff694f62da6410618bd73853cb"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/ecc6dec12c33aa92c086cd702af9f544ddaf3c75"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
]
}
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.