CVE-2022-49978 (GCVE-0-2022-49978)

Vulnerability from cvelistv5 – Published: 2025-06-18 11:00 – Updated: 2025-12-23 13:26
VLAI?
Title
fbdev: fb_pm2fb: Avoid potential divide by zero error
Summary
In the Linux kernel, the following vulnerability has been resolved: fbdev: fb_pm2fb: Avoid potential divide by zero error In `do_fb_ioctl()` of fbmem.c, if cmd is FBIOPUT_VSCREENINFO, var will be copied from user, then go through `fb_set_var()` and `info->fbops->fb_check_var()` which could may be `pm2fb_check_var()`. Along the path, `var->pixclock` won't be modified. This function checks whether reciprocal of `var->pixclock` is too high. If `var->pixclock` is zero, there will be a divide by zero error. So, it is necessary to check whether denominator is zero to avoid crash. As this bug is found by Syzkaller, logs are listed below. divide error in pm2fb_check_var Call Trace: <TASK> fb_set_var+0x367/0xeb0 drivers/video/fbdev/core/fbmem.c:1015 do_fb_ioctl+0x234/0x670 drivers/video/fbdev/core/fbmem.c:1110 fb_ioctl+0xdd/0x130 drivers/video/fbdev/core/fbmem.c:1189
Severity ?
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 0f1174f4972ea9fad6becf8881d71adca8e9ca91 (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 3ec326a6a0d4667585ca595f438c7293e5ced7c4 (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 7f88cdfea8d7f4dbaf423d808241403b2bb945e4 (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 7d9591b32a9092fc6391a316b56e8016c6181c3d (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 8fc778ee2fb2853f7a3531fa7273349640d8e4e9 (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 34c3dea1189525cd533071ed5c176fc4ea8d982b (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < cb4bb011a683532841344ca7f281b5e04389b4f8 (git)
Affected: 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 , < 19f953e7435644b81332dd632ba1b2d80b1e37af (git)
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    Linux Linux Affected: 2.6.12
Unaffected: 0 , < 2.6.12 (semver)
Unaffected: 4.9.327 , ≤ 4.9.* (semver)
Unaffected: 4.14.292 , ≤ 4.14.* (semver)
Unaffected: 4.19.257 , ≤ 4.19.* (semver)
Unaffected: 5.4.212 , ≤ 5.4.* (semver)
Unaffected: 5.10.141 , ≤ 5.10.* (semver)
Unaffected: 5.15.65 , ≤ 5.15.* (semver)
Unaffected: 5.19.7 , ≤ 5.19.* (semver)
Unaffected: 6.0 , ≤ * (original_commit_for_fix)
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      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nfbdev: fb_pm2fb: Avoid potential divide by zero error\n\nIn `do_fb_ioctl()` of fbmem.c, if cmd is FBIOPUT_VSCREENINFO, var will be\ncopied from user, then go through `fb_set_var()` and\n`info-\u003efbops-\u003efb_check_var()` which could may be `pm2fb_check_var()`.\nAlong the path, `var-\u003epixclock` won\u0027t be modified. This function checks\nwhether reciprocal of `var-\u003epixclock` is too high. If `var-\u003epixclock` is\nzero, there will be a divide by zero error. So, it is necessary to check\nwhether denominator is zero to avoid crash. As this bug is found by\nSyzkaller, logs are listed below.\n\ndivide error in pm2fb_check_var\nCall Trace:\n \u003cTASK\u003e\n fb_set_var+0x367/0xeb0 drivers/video/fbdev/core/fbmem.c:1015\n do_fb_ioctl+0x234/0x670 drivers/video/fbdev/core/fbmem.c:1110\n fb_ioctl+0xdd/0x130 drivers/video/fbdev/core/fbmem.c:1189"
        }
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        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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          "url": "https://git.kernel.org/stable/c/3ec326a6a0d4667585ca595f438c7293e5ced7c4"
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          "url": "https://git.kernel.org/stable/c/7f88cdfea8d7f4dbaf423d808241403b2bb945e4"
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        {
          "url": "https://git.kernel.org/stable/c/7d9591b32a9092fc6391a316b56e8016c6181c3d"
        },
        {
          "url": "https://git.kernel.org/stable/c/8fc778ee2fb2853f7a3531fa7273349640d8e4e9"
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        {
          "url": "https://git.kernel.org/stable/c/34c3dea1189525cd533071ed5c176fc4ea8d982b"
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        {
          "url": "https://git.kernel.org/stable/c/cb4bb011a683532841344ca7f281b5e04389b4f8"
        },
        {
          "url": "https://git.kernel.org/stable/c/19f953e7435644b81332dd632ba1b2d80b1e37af"
        }
      ],
      "title": "fbdev: fb_pm2fb: Avoid potential divide by zero error",
      "x_generator": {
        "engine": "bippy-1.2.0"
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    "assignerShortName": "Linux",
    "cveId": "CVE-2022-49978",
    "datePublished": "2025-06-18T11:00:40.693Z",
    "dateReserved": "2025-06-18T10:57:27.385Z",
    "dateUpdated": "2025-12-23T13:26:17.111Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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