{"id":"CVE-2021-47280","state":"PUBLISHED","title":"drm: Fix use-after-free read in drm_getunique()","description":"In the Linux kernel, the following vulnerability has been resolved:\n\ndrm: Fix use-after-free read in drm_getunique()\n\nThere is a time-of-check-to-time-of-use error in drm_getunique() due\nto retrieving file_priv->master prior to locking the device's master\nmutex.\n\nAn example can be seen in the crash report of the use-after-free error\nfound by Syzbot:\nhttps://syzkaller.appspot.com/bug?id=148d2f1dfac64af52ffd27b661981a540724f803\n\nIn the report, the master pointer was used after being freed. This is\nbecause another process had acquired the device's master mutex in\ndrm_setmaster_ioctl(), then overwrote fpriv->master in\ndrm_new_set_master(). The old value of fpriv->master was subsequently\nfreed before the mutex was unlocked.\n\nTo fix this, we lock the device's master mutex before retrieving the\npointer from from fpriv->master. This patch passes the Syzbot\nreproducer test.","publishedAt":"2024-05-21T14:20:06.852Z","updatedAt":"2026-05-11T13:51:27.366Z","severity":null,"assigner":"Linux","products":["Linux Linux"],"affected":[{"vendor":"Linux","product":"Linux","defaultStatus":"unaffected","versions":[{"version":"5acc614ac47465fee6375a9af4740f618830762d","status":"affected","lessThan":"17dab9326ff263c62dab1dbac4492e2938a049e4","versionType":"git"},{"version":"5acc614ac47465fee6375a9af4740f618830762d","status":"affected","lessThan":"7d233ba700ceb593905ea82b42dadb4ec8ef85e9","versionType":"git"},{"version":"5acc614ac47465fee6375a9af4740f618830762d","status":"affected","lessThan":"b246b4c70c1250e7814f409b243000f9c0bf79a3","versionType":"git"},{"version":"5acc614ac47465fee6375a9af4740f618830762d","status":"affected","lessThan":"491d52e0078860b33b6c14f0a7ac74ca1b603bd6","versionType":"git"},{"version":"5acc614ac47465fee6375a9af4740f618830762d","status":"affected","lessThan":"f773f8cccac13c7e7bbd9182e7996c727742488e","versionType":"git"},{"version":"5acc614ac47465fee6375a9af4740f618830762d","status":"affected","lessThan":"b436acd1cf7fac0ba987abd22955d98025c80c2b","versionType":"git"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/gpu/drm/drm_ioctl.c"]},{"vendor":"Linux","product":"Linux","defaultStatus":"affected","versions":[{"version":"4.11","status":"affected"},{"version":"0","status":"unaffected","lessThan":"4.11","versionType":"semver"},{"version":"4.14.237","status":"unaffected","lessThanOrEqual":"4.14.*","versionType":"semver"},{"version":"4.19.195","status":"unaffected","lessThanOrEqual":"4.19.*","versionType":"semver"},{"version":"5.4.126","status":"unaffected","lessThanOrEqual":"5.4.*","versionType":"semver"},{"version":"5.10.44","status":"unaffected","lessThanOrEqual":"5.10.*","versionType":"semver"},{"version":"5.12.11","status":"unaffected","lessThanOrEqual":"5.12.*","versionType":"semver"},{"version":"5.13","status":"unaffected","lessThanOrEqual":"*","versionType":"original_commit_for_fix"}],"repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","programFiles":["drivers/gpu/drm/drm_ioctl.c"]}],"references":["https://git.kernel.org/stable/c/17dab9326ff263c62dab1dbac4492e2938a049e4","https://git.kernel.org/stable/c/7d233ba700ceb593905ea82b42dadb4ec8ef85e9","https://git.kernel.org/stable/c/b246b4c70c1250e7814f409b243000f9c0bf79a3","https://git.kernel.org/stable/c/491d52e0078860b33b6c14f0a7ac74ca1b603bd6","https://git.kernel.org/stable/c/f773f8cccac13c7e7bbd9182e7996c727742488e","https://git.kernel.org/stable/c/b436acd1cf7fac0ba987abd22955d98025c80c2b"],"weaknesses":[],"ingestedAt":"2026-10-29T19:49:19.404Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2021/47xxx/CVE-2021-47280.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.2","cveMetadata":{"cveId":"CVE-2021-47280","state":"PUBLISHED","datePublished":"2024-05-21T14:20:06.852Z","dateUpdated":"2026-05-11T13:51:27.366Z","assignerShortName":"Linux","assignerOrgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","dateReserved":"2024-05-21T13:27:52.128Z"},"containers":{"cna":{"title":"drm: Fix use-after-free read in drm_getunique()","descriptions":[{"lang":"en","value":"In the Linux kernel, the following vulnerability has been resolved:\n\ndrm: Fix use-after-free read in drm_getunique()\n\nThere is a time-of-check-to-time-of-use error in drm_getunique() due\nto retrieving file_priv->master prior to locking the device's master\nmutex.\n\nAn example can be seen in the crash report of the use-after-free error\nfound by Syzbot:\nhttps://syzkaller.appspot.com/bug?id=148d2f1dfac64af52ffd27b661981a540724f803\n\nIn the report, the master pointer was used after being freed. This is\nbecause another process had acquired the device's master mutex in\ndrm_setmaster_ioctl(), then overwrote fpriv->master in\ndrm_new_set_master(). The old value of fpriv->master was subsequently\nfreed before the mutex was unlocked.\n\nTo fix this, we lock the device's master mutex before retrieving the\npointer from from fpriv->master. 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