GHSA-RH6V-853J-MQJH
Vulnerability from github – Published: 2025-04-18 15:31 – Updated: 2025-11-03 21:33In the Linux kernel, the following vulnerability has been resolved:
jfs: fix slab-out-of-bounds read in ea_get()
During the "size_check" label in ea_get(), the code checks if the extended attribute list (xattr) size matches ea_size. If not, it logs "ea_get: invalid extended attribute" and calls print_hex_dump().
Here, EALIST_SIZE(ea_buf->xattr) returns 4110417968, which exceeds INT_MAX (2,147,483,647). Then ea_size is clamped:
int size = clamp_t(int, ea_size, 0, EALIST_SIZE(ea_buf->xattr));
Although clamp_t aims to bound ea_size between 0 and 4110417968, the upper limit is treated as an int, causing an overflow above 2^31 - 1. This leads "size" to wrap around and become negative (-184549328).
The "size" is then passed to print_hex_dump() (called "len" in print_hex_dump()), it is passed as type size_t (an unsigned type), this is then stored inside a variable called "int remaining", which is then assigned to "int linelen" which is then passed to hex_dump_to_buffer(). In print_hex_dump() the for loop, iterates through 0 to len-1, where len is 18446744073525002176, calling hex_dump_to_buffer() on each iteration:
for (i = 0; i < len; i += rowsize) {
linelen = min(remaining, rowsize);
remaining -= rowsize;
hex_dump_to_buffer(ptr + i, linelen, rowsize, groupsize,
linebuf, sizeof(linebuf), ascii);
...
}
The expected stopping condition (i < len) is effectively broken since len is corrupted and very large. This eventually leads to the "ptr+i" being passed to hex_dump_to_buffer() to get closer to the end of the actual bounds of "ptr", eventually an out of bounds access is done in hex_dump_to_buffer() in the following for loop:
for (j = 0; j < len; j++) {
if (linebuflen < lx + 2)
goto overflow2;
ch = ptr[j];
...
}
To fix this we should validate "EALIST_SIZE(ea_buf->xattr)" before it is utilised.
{
"affected": [],
"aliases": [
"CVE-2025-39735"
],
"database_specific": {
"cwe_ids": [
"CWE-125"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2025-04-18T07:15:44Z",
"severity": "HIGH"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\njfs: fix slab-out-of-bounds read in ea_get()\n\nDuring the \"size_check\" label in ea_get(), the code checks if the extended\nattribute list (xattr) size matches ea_size. If not, it logs\n\"ea_get: invalid extended attribute\" and calls print_hex_dump().\n\nHere, EALIST_SIZE(ea_buf-\u003exattr) returns 4110417968, which exceeds\nINT_MAX (2,147,483,647). Then ea_size is clamped:\n\n\tint size = clamp_t(int, ea_size, 0, EALIST_SIZE(ea_buf-\u003exattr));\n\nAlthough clamp_t aims to bound ea_size between 0 and 4110417968, the upper\nlimit is treated as an int, causing an overflow above 2^31 - 1. This leads\n\"size\" to wrap around and become negative (-184549328).\n\nThe \"size\" is then passed to print_hex_dump() (called \"len\" in\nprint_hex_dump()), it is passed as type size_t (an unsigned\ntype), this is then stored inside a variable called\n\"int remaining\", which is then assigned to \"int linelen\" which\nis then passed to hex_dump_to_buffer(). In print_hex_dump()\nthe for loop, iterates through 0 to len-1, where len is\n18446744073525002176, calling hex_dump_to_buffer()\non each iteration:\n\n\tfor (i = 0; i \u003c len; i += rowsize) {\n\t\tlinelen = min(remaining, rowsize);\n\t\tremaining -= rowsize;\n\n\t\thex_dump_to_buffer(ptr + i, linelen, rowsize, groupsize,\n\t\t\t\t linebuf, sizeof(linebuf), ascii);\n\n\t\t...\n\t}\n\nThe expected stopping condition (i \u003c len) is effectively broken\nsince len is corrupted and very large. This eventually leads to\nthe \"ptr+i\" being passed to hex_dump_to_buffer() to get closer\nto the end of the actual bounds of \"ptr\", eventually an out of\nbounds access is done in hex_dump_to_buffer() in the following\nfor loop:\n\n\tfor (j = 0; j \u003c len; j++) {\n\t\t\tif (linebuflen \u003c lx + 2)\n\t\t\t\tgoto overflow2;\n\t\t\tch = ptr[j];\n\t\t...\n\t}\n\nTo fix this we should validate \"EALIST_SIZE(ea_buf-\u003exattr)\"\nbefore it is utilised.",
"id": "GHSA-rh6v-853j-mqjh",
"modified": "2025-11-03T21:33:41Z",
"published": "2025-04-18T15:31:38Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2025-39735"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/0beddc2a3f9b9cf7d8887973041e36c2d0fa3652"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/16d3d36436492aa248b2d8045e75585ebcc2f34d"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/3d6fd5b9c6acbc005e53d0211c7381f566babec1"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/46e2c031aa59ea65128991cbca474bd5c0c2ecdb"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/50afcee7011155933d8d5e8832f52eeee018cfd3"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/5263822558a8a7c0d0248d5679c2dcf4d5cda61f"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/78c9cbde8880ec02d864c166bcb4fe989ce1d95f"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/a8c31808925b11393a6601f534bb63bac5366bab"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/fdf480da5837c23b146c4743c18de97202fcab37"
},
{
"type": "WEB",
"url": "https://lists.debian.org/debian-lts-announce/2025/05/msg00030.html"
},
{
"type": "WEB",
"url": "https://lists.debian.org/debian-lts-announce/2025/05/msg00045.html"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:H",
"type": "CVSS_V3"
}
]
}
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