GHSA-W38V-PHV7-FJQ8
Vulnerability from github – Published: 2024-10-21 18:30 – Updated: 2025-11-04 00:31In the Linux kernel, the following vulnerability has been resolved:
ext4: aovid use-after-free in ext4_ext_insert_extent()
As Ojaswin mentioned in Link, in ext4_ext_insert_extent(), if the path is reallocated in ext4_ext_create_new_leaf(), we'll use the stale path and cause UAF. Below is a sample trace with dummy values:
ext4_ext_insert_extent path = ppath = 2000 ext4_ext_create_new_leaf(ppath) ext4_find_extent(ppath) path = ppath = 2000 if (depth > path[0].p_maxdepth) kfree(path = 2000); ppath = path = NULL; path = kcalloc() = 3000 ppath = 3000; return path; / here path is still 2000, UAF! / eh = path[depth].p_hdr
================================================================== BUG: KASAN: slab-use-after-free in ext4_ext_insert_extent+0x26d4/0x3330 Read of size 8 at addr ffff8881027bf7d0 by task kworker/u36:1/179 CPU: 3 UID: 0 PID: 179 Comm: kworker/u6:1 Not tainted 6.11.0-rc2-dirty #866 Call Trace: ext4_ext_insert_extent+0x26d4/0x3330 ext4_ext_map_blocks+0xe22/0x2d40 ext4_map_blocks+0x71e/0x1700 ext4_do_writepages+0x1290/0x2800 [...]
Allocated by task 179: ext4_find_extent+0x81c/0x1f70 ext4_ext_map_blocks+0x146/0x2d40 ext4_map_blocks+0x71e/0x1700 ext4_do_writepages+0x1290/0x2800 ext4_writepages+0x26d/0x4e0 do_writepages+0x175/0x700 [...]
Freed by task 179: kfree+0xcb/0x240 ext4_find_extent+0x7c0/0x1f70 ext4_ext_insert_extent+0xa26/0x3330 ext4_ext_map_blocks+0xe22/0x2d40 ext4_map_blocks+0x71e/0x1700 ext4_do_writepages+0x1290/0x2800 ext4_writepages+0x26d/0x4e0 do_writepages+0x175/0x700 [...] ==================================================================
So use *ppath to update the path to avoid the above problem.
{
"affected": [],
"aliases": [
"CVE-2024-49883"
],
"database_specific": {
"cwe_ids": [
"CWE-416"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-10-21T18:15:11Z",
"severity": "HIGH"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\next4: aovid use-after-free in ext4_ext_insert_extent()\n\nAs Ojaswin mentioned in Link, in ext4_ext_insert_extent(), if the path is\nreallocated in ext4_ext_create_new_leaf(), we\u0027ll use the stale path and\ncause UAF. Below is a sample trace with dummy values:\n\next4_ext_insert_extent\n path = *ppath = 2000\n ext4_ext_create_new_leaf(ppath)\n ext4_find_extent(ppath)\n path = *ppath = 2000\n if (depth \u003e path[0].p_maxdepth)\n kfree(path = 2000);\n *ppath = path = NULL;\n path = kcalloc() = 3000\n *ppath = 3000;\n return path;\n /* here path is still 2000, UAF! */\n eh = path[depth].p_hdr\n\n==================================================================\nBUG: KASAN: slab-use-after-free in ext4_ext_insert_extent+0x26d4/0x3330\nRead of size 8 at addr ffff8881027bf7d0 by task kworker/u36:1/179\nCPU: 3 UID: 0 PID: 179 Comm: kworker/u6:1 Not tainted 6.11.0-rc2-dirty #866\nCall Trace:\n \u003cTASK\u003e\n ext4_ext_insert_extent+0x26d4/0x3330\n ext4_ext_map_blocks+0xe22/0x2d40\n ext4_map_blocks+0x71e/0x1700\n ext4_do_writepages+0x1290/0x2800\n[...]\n\nAllocated by task 179:\n ext4_find_extent+0x81c/0x1f70\n ext4_ext_map_blocks+0x146/0x2d40\n ext4_map_blocks+0x71e/0x1700\n ext4_do_writepages+0x1290/0x2800\n ext4_writepages+0x26d/0x4e0\n do_writepages+0x175/0x700\n[...]\n\nFreed by task 179:\n kfree+0xcb/0x240\n ext4_find_extent+0x7c0/0x1f70\n ext4_ext_insert_extent+0xa26/0x3330\n ext4_ext_map_blocks+0xe22/0x2d40\n ext4_map_blocks+0x71e/0x1700\n ext4_do_writepages+0x1290/0x2800\n ext4_writepages+0x26d/0x4e0\n do_writepages+0x175/0x700\n[...]\n==================================================================\n\nSo use *ppath to update the path to avoid the above problem.",
"id": "GHSA-w38v-phv7-fjq8",
"modified": "2025-11-04T00:31:40Z",
"published": "2024-10-21T18:30:57Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-49883"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/51db04892a993cace63415be99848970a0f15ef2"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/5e811066c5ab709b070659197dccfb80ab650ddd"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/8162ee5d94b8c0351be0a9321be134872a7654a1"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/975ca06f3fd154c5f7742083e7b2574c57d1c0c3"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/9df59009dfc6d9fc1bd9ddf6c5ab6e56d6ed887a"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/a164f3a432aae62ca23d03e6d926b122ee5b860d"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/beb7b66fb489041c50c6473100b383f7a51648fc"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/bfed082ce4b1ce6349b05c09a0fa4f3da35ecb1b"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/e17ebe4fdd7665c93ae9459ba40fcdfb76769ac1"
},
{
"type": "WEB",
"url": "https://lists.debian.org/debian-lts-announce/2025/01/msg00001.html"
},
{
"type": "WEB",
"url": "https://lists.debian.org/debian-lts-announce/2025/03/msg00002.html"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
"type": "CVSS_V3"
}
]
}
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