FKIE_CVE-2025-38415

Vulnerability from fkie_nvd - Published: 2025-07-25 14:15 - Updated: 2025-12-23 18:45
Severity ?
7.8 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: Squashfs: check return result of sb_min_blocksize Syzkaller reports an "UBSAN: shift-out-of-bounds in squashfs_bio_read" bug. Syzkaller forks multiple processes which after mounting the Squashfs filesystem, issues an ioctl("/dev/loop0", LOOP_SET_BLOCK_SIZE, 0x8000). Now if this ioctl occurs at the same time another process is in the process of mounting a Squashfs filesystem on /dev/loop0, the failure occurs. When this happens the following code in squashfs_fill_super() fails. ---- msblk->devblksize = sb_min_blocksize(sb, SQUASHFS_DEVBLK_SIZE); msblk->devblksize_log2 = ffz(~msblk->devblksize); ---- sb_min_blocksize() returns 0, which means msblk->devblksize is set to 0. As a result, ffz(~msblk->devblksize) returns 64, and msblk->devblksize_log2 is set to 64. This subsequently causes the UBSAN: shift-out-of-bounds in fs/squashfs/block.c:195:36 shift exponent 64 is too large for 64-bit type 'u64' (aka 'unsigned long long') This commit adds a check for a 0 return by sb_min_blocksize().
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/0aff95d9bc7fb5400ca8af507429c4b067bdb425Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/295ab18c2dbce8d0ac6ecf7c5187e16e1ac8b282Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/4f99357dadbf9c979ad737156ad4c37fadf7c56bPatch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/549f9e3d7b60d53808c98b9fde49b4f46d0524a5Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/5c51aa862cbeed2f3887f0382a2708956710bd68Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/6abf6b78c6fb112eee495f5636ffcc350dd2ce25Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/734aa85390ea693bb7eaf2240623d41b03705c84Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/db7096ea160e40d78c67fce52e7cc51bde049497Patch
af854a3a-2127-422b-91ae-364da2661108https://lists.debian.org/debian-lts-announce/2025/10/msg00007.htmlThird Party Advisory, Mailing List
af854a3a-2127-422b-91ae-364da2661108https://lists.debian.org/debian-lts-announce/2025/10/msg00008.htmlThird Party Advisory, Mailing List
Impacted products
Vendor Product Version
linux linux_kernel *
linux linux_kernel *
linux linux_kernel *
linux linux_kernel *
linux linux_kernel *
linux linux_kernel *
linux linux_kernel *
debian debian_linux 11.0
To clipboard 

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      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nSquashfs: check return result of sb_min_blocksize\n\nSyzkaller reports an \"UBSAN: shift-out-of-bounds in squashfs_bio_read\" bug.\n\nSyzkaller forks multiple processes which after mounting the Squashfs\nfilesystem, issues an ioctl(\"/dev/loop0\", LOOP_SET_BLOCK_SIZE, 0x8000). \nNow if this ioctl occurs at the same time another process is in the\nprocess of mounting a Squashfs filesystem on /dev/loop0, the failure\noccurs.  When this happens the following code in squashfs_fill_super()\nfails.\n\n----\nmsblk-\u003edevblksize = sb_min_blocksize(sb, SQUASHFS_DEVBLK_SIZE);\nmsblk-\u003edevblksize_log2 = ffz(~msblk-\u003edevblksize);\n----\n\nsb_min_blocksize() returns 0, which means msblk-\u003edevblksize is set to 0.\n\nAs a result, ffz(~msblk-\u003edevblksize) returns 64, and msblk-\u003edevblksize_log2\nis set to 64.\n\nThis subsequently causes the\n\nUBSAN: shift-out-of-bounds in fs/squashfs/block.c:195:36\nshift exponent 64 is too large for 64-bit type \u0027u64\u0027 (aka\n\u0027unsigned long long\u0027)\n\nThis commit adds a check for a 0 return by sb_min_blocksize()."
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    {
      "lang": "es",
      "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: Squashfs: comprobar el resultado devuelto de sb_min_blocksize. Syzkaller informa del error \"UBSAN: desplazamiento fuera de los l\u00edmites en squashfs_bio_read\". Syzkaller bifurca varios procesos que, tras montar el sistema de archivos Squashfs, emiten una instrucci\u00f3n ioctl(\"/dev/loop0\", LOOP_SET_BLOCK_SIZE, 0x8000). Si esta instrucci\u00f3n ioctl se produce al mismo tiempo que otro proceso est\u00e1 montando un sistema de archivos Squashfs en /dev/loop0, se produce el fallo. En este caso, el siguiente c\u00f3digo en squashfs_fill_super() falla: ---- msblk-\u0026gt;devblksize = sb_min_blocksize(sb, SQUASHFS_DEVBLK_SIZE); msblk-\u0026gt;devblksize_log2 = ffz(~msblk-\u0026gt;devblksize); ---- sb_min_blocksize() devuelve 0, lo que significa que msblk-\u0026gt;devblksize est\u00e1 establecido en 0. Como resultado, ffz(~msblk-\u0026gt;devblksize) devuelve 64 y msblk-\u0026gt;devblksize_log2 est\u00e1 establecido en 64. Esto posteriormente provoca el UBSAN: shift-out-of-bounds en fs/squashfs/block.c:195:36 el exponente de desplazamiento 64 es demasiado grande para el tipo de 64 bits \u0027u64\u0027 (tambi\u00e9n conocido como \u0027unsigned long long\u0027) Esta confirmaci\u00f3n agrega una comprobaci\u00f3n para un retorno de 0 por sb_min_blocksize()."
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  "id": "CVE-2025-38415",
  "lastModified": "2025-12-23T18:45:31.653",
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          "baseScore": 7.8,
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          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
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