{ "schemaVersion": 1, "attribution": [ { "source": "CISA Known Exploited Vulnerabilities", "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog", "licence": "US government work" }, { "source": "GitHub Advisory Database", "url": "https://github.com/advisories", "licence": "CC BY 4.0" }, { "source": "Have I Been Pwned", "url": "https://haveibeenpwned.com/", "licence": "CC BY 4.0" }, { "source": "CVE Program (CVE records)", "url": "https://www.cve.org/Legal/TermsOfUse", "licence": "CVE Terms of Use", "notice": "Copyright © 1999-2026, The MITRE Corporation. CVE is a trademark and the CVE logo is a registered trademark of The MITRE Corporation.", "terms": "CVE Usage: MITRE hereby grants you a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable copyright license to reproduce, prepare derivative works of, publicly display, publicly perform, sublicense, and distribute Common Vulnerabilities and Exposures (CVE™). Any copy you make for such purposes is authorized provided that you reproduce MITRE's copyright designation and this license in any such copy." }, { "source": "FIRST EPSS", "url": "https://www.first.org/epss/", "licence": "free to use; FIRST requests attribution" } ], "record": { "id": "CVE-2021-47375", "sourceURL": "https://www.cve.org/CVERecord?id=CVE-2021-47375", "idYear": 2021, "status": "PUBLISHED", "publishedAt": "2024-05-21T15:03:39.090Z", "updatedAt": "2026-05-11T13:53:29.691Z", "importedAt": "2026-10-24T01:56:36.661Z", "snapshot": { "id": "cve_2026-10-24_midnight_baseline", "at": "2026-10-24T00:00:00.000Z", "source": "https://github.com/CVEProject/cvelistV5/releases/tag/cve_2026-10-24_0100Z" }, "facts": { "title": "blktrace: Fix uaf in blk_trace access after removing by sysfs", "summary": "In the Linux kernel, the following vulnerability has been resolved:\n\nblktrace: Fix uaf in blk_trace access after removing by sysfs\n\nThere is an use-after-free problem triggered by following process:\n\n P1(sda)\t\t\t\tP2(sdb)\n\t\t\techo 0 > /sys/block/sdb/trace/enable\n\t\t\t blk_trace_remove_queue\n\t\t\t synchronize_rcu\n\t\t\t blk_trace_free\n\t\t\t relay_close\nrcu_read_lock\n__blk_add_trace\n trace_note_tsk\n (Iterate running_trace_list)\n\t\t\t relay_close_buf\n\t\t\t\t relay_destroy_buf\n\t\t\t\t kfree(buf)\n trace_note(sdb's bt)\n relay_reserve\n buf->offset <- nullptr deference (use-after-free) !!!\nrcu_read_unlock\n\n[ 502.714379] BUG: kernel NULL pointer dereference, address:\n0000000000000010\n[ 502.715260] #PF: supervisor read access in kernel mode\n[ 502.715903] #PF: error_code(0x0000) - not-present page\n[ 502.716546] PGD 103984067 P4D 103984067 PUD 17592b067 PMD 0\n[ 502.717252] Oops: 0000 [#1] SMP\n[ 502.720308] RIP: 0010:trace_note.isra.0+0x86/0x360\n[ 502.732872] Call Trace:\n[ 502.733193] __blk_add_trace.cold+0x137/0x1a3\n[ 502.733734] blk_add_trace_rq+0x7b/0xd0\n[ 502.734207] blk_add_trace_rq_issue+0x54/0xa0\n[ 502.734755] blk_mq_start_request+0xde/0x1b0\n[ 502.735287] scsi_queue_rq+0x528/0x1140\n...\n[ 502.742704] sg_new_write.isra.0+0x16e/0x3e0\n[ 502.747501] sg_ioctl+0x466/0x1100\n\nReproduce method:\n ioctl(/dev/sda, BLKTRACESETUP, blk_user_trace_setup[buf_size=127])\n ioctl(/dev/sda, BLKTRACESTART)\n ioctl(/dev/sdb, BLKTRACESETUP, blk_user_trace_setup[buf_size=127])\n ioctl(/dev/sdb, BLKTRACESTART)\n\n echo 0 > /sys/block/sdb/trace/enable &\n // Add delay(mdelay/msleep) before kernel enters blk_trace_free()\n\n ioctl$SG_IO(/dev/sda, SG_IO, ...)\n // Enters trace_note_tsk() after blk_trace_free() returned\n // Use mdelay in rcu region rather than msleep(which may schedule out)\n\nRemove blk_trace from running_list before calling blk_trace_free() by\nsysfs if blk_trace is at Blktrace_running state.", "affected": [ { "vendor": "Linux", "product": "Linux", "defaultStatus": "unaffected", "versions": [ { "version": "c71a896154119f4ca9e89d6078f5f63ad60ef199", "status": "affected", "versionType": "git", "lessThan": "488da313edf3abea7f7733efe011c96b23740ab5" }, { "version": "c71a896154119f4ca9e89d6078f5f63ad60ef199", "status": "affected", "versionType": "git", "lessThan": "dacfd5e4d1142bfb3809aab3634a375f6f373269" }, { "version": "c71a896154119f4ca9e89d6078f5f63ad60ef199", "status": "affected", "versionType": "git", "lessThan": "d56171d9360c0170c5c5f8f7e2362a2e999eca40" }, { "version": "c71a896154119f4ca9e89d6078f5f63ad60ef199", "status": "affected", "versionType": "git", "lessThan": "677e362ba807f3aafe6f405c07e0b37244da5222" }, { "version": "c71a896154119f4ca9e89d6078f5f63ad60ef199", "status": "affected", "versionType": "git", "lessThan": "ebb8d26d93c3ec3c7576c52a8373a2309423c069" }, { "version": "c71a896154119f4ca9e89d6078f5f63ad60ef199", "status": "affected", "versionType": "git", "lessThan": "3815fe7371d2411ce164281cef40d9fc7b323dee" }, { "version": "c71a896154119f4ca9e89d6078f5f63ad60ef199", "status": "affected", "versionType": "git", "lessThan": "a5f8e86192612d0183047448d8bbe7918b3f1a26" }, { "version": "c71a896154119f4ca9e89d6078f5f63ad60ef199", "status": "affected", "versionType": "git", "lessThan": "5afedf670caf30a2b5a52da96eb7eac7dee6a9c9" } ] }, { "vendor": "Linux", "product": "Linux", "defaultStatus": "affected", "versions": [ { "version": "2.6.30", "status": "affected" }, { "version": "0", "status": "unaffected", "versionType": "semver", "lessThan": "2.6.30" }, { "version": "4.4.286", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "4.4.*" }, { "version": "4.9.285", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "4.9.*" }, { "version": "4.14.249", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "4.14.*" }, { "version": "4.19.209", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "4.19.*" }, { "version": "5.4.150", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "5.4.*" }, { "version": "5.10.70", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "5.10.*" }, { "version": "5.14.9", "status": "unaffected", "versionType": "semver", "lessThanOrEqual": "5.14.*" }, { "version": "5.15", "status": "unaffected", "versionType": "original_commit_for_fix", "lessThanOrEqual": "*" } ] } ] } } }