{ "dataType": "CVE_RECORD", "dataVersion": "5.2", "cveMetadata": { "cveId": "CVE-2021-47544", "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "state": "PUBLISHED", "assignerShortName": "Linux", "dateReserved": "2024-05-24T15:02:54.829Z", "datePublished": "2024-05-24T15:09:49.895Z", "dateUpdated": "2026-08-05T08:48:19.884Z" }, "containers": { "cna": { "providerMetadata": { "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67", "shortName": "Linux", "dateUpdated": "2026-08-05T08:48:19.884Z" }, "descriptions": [ { "lang": "en", "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ntcp: fix page frag corruption on page fault\n\nSteffen reported a TCP stream corruption for HTTP requests\nserved by the apache web-server using a cifs mount-point\nand memory mapping the relevant file.\n\nThe root cause is quite similar to the one addressed by\ncommit 20eb4f29b602 (\"net: fix sk_page_frag() recursion from\nmemory reclaim\"). Here the nested access to the task page frag\nis caused by a page fault on the (mmapped) user-space memory\nbuffer coming from the cifs file.\n\nThe page fault handler performs an smb transaction on a different\nsocket, inside the same process context. Since sk->sk_allaction\nfor such socket does not prevent the usage for the task_frag,\nthe nested allocation modify \"under the hood\" the page frag\nin use by the outer sendmsg call, corrupting the stream.\n\nThe overall relevant stack trace looks like the following:\n\nhttpd 78268 [001] 3461630.850950: probe:tcp_sendmsg_locked:\n ffffffff91461d91 tcp_sendmsg_locked+0x1\n ffffffff91462b57 tcp_sendmsg+0x27\n ffffffff9139814e sock_sendmsg+0x3e\n ffffffffc06dfe1d smb_send_kvec+0x28\n [...]\n ffffffffc06cfaf8 cifs_readpages+0x213\n ffffffff90e83c4b read_pages+0x6b\n ffffffff90e83f31 __do_page_cache_readahead+0x1c1\n ffffffff90e79e98 filemap_fault+0x788\n ffffffff90eb0458 __do_fault+0x38\n ffffffff90eb5280 do_fault+0x1a0\n ffffffff90eb7c84 __handle_mm_fault+0x4d4\n ffffffff90eb8093 handle_mm_fault+0xc3\n ffffffff90c74f6d __do_page_fault+0x1ed\n ffffffff90c75277 do_page_fault+0x37\n ffffffff9160111e page_fault+0x1e\n ffffffff9109e7b5 copyin+0x25\n ffffffff9109eb40 _copy_from_iter_full+0xe0\n ffffffff91462370 tcp_sendmsg_locked+0x5e0\n ffffffff91462370 tcp_sendmsg_locked+0x5e0\n ffffffff91462b57 tcp_sendmsg+0x27\n ffffffff9139815c sock_sendmsg+0x4c\n ffffffff913981f7 sock_write_iter+0x97\n ffffffff90f2cc56 do_iter_readv_writev+0x156\n ffffffff90f2dff0 do_iter_write+0x80\n ffffffff90f2e1c3 vfs_writev+0xa3\n ffffffff90f2e27c do_writev+0x5c\n ffffffff90c042bb do_syscall_64+0x5b\n ffffffff916000ad entry_SYSCALL_64_after_hwframe+0x65\n\nThe cifs filesystem rightfully sets sk_allocations to GFP_NOFS,\nwe can avoid the nesting using the sk page frag for allocation\nlacking the __GFP_FS flag. Do not define an additional mm-helper\nfor that, as this is strictly tied to the sk page frag usage.\n\nv1 -> v2:\n - use a stricted sk_page_frag() check instead of reordering the\n code (Eric)" } ], "metrics": [ { "cvssV3_1": { "version": "3.1", "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H", "baseScore": 9.8, "baseSeverity": "CRITICAL" }, "scenarios": [ { "lang": "en", "value": "AV:N - Worst reasonable case is an internet-facing service (e.g. HTTP) sending mmap’d content from a GFP_NOFS/GFP_NOIO network filesystem (CIFS/Ceph/9p), so a remote peer’s requests drive the vulnerable tcp_sendmsg/sk_page_frag path without local shell access.\nAC:L - Given that deployment, the attacker can reliably force page faults by requesting uncached network-FS-backed data; nesting is deterministic on fault, not a race or layout condition outside attacker influence.\nPR:N - Unauthenticated remote clients of the network-facing service need no host account or capabilities; the vulnerable send path runs in the server process on their requests.\nUI:N - No separate victim action is required beyond the service already serving network-FS-backed buffers; the attacker’s requests alone trigger sendmsg and the nested fault path.\nS:U - Impact is kernel memory corruption and privilege escalation within the same host kernel authority, not a VM/IOMMU or other cross-boundary escape.\nC:H - Corrupted page-frag state can attach and transmit unintended page contents (including nested SMB/FS data or adjacent bytes), and the subsequent size-offset underflow OOB enables broader kernel memory disclosure.\nI:H - Nested task_frag mutation yields out-of-bounds writes past page-frag buffers via unsigned size-offset underflow into copy_from_iter, which is heap memory corruption exploitable for arbitrary write/control-flow hijack.\nA:H - The same OOB/heap corruption can oops or panic the kernel, and related task_frag recursion bugs have manifested as crashes even when not fully exploited." } ] } ], "affected": [ { "product": "Linux", "vendor": "Linux", "defaultStatus": "unaffected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "include/net/sock.h" ], "versions": [ { "version": "5640f7685831e088fe6c2e1f863a6805962f8e81", "lessThan": "c6f340a331fb72e5ac23a083de9c780e132ca3ae", "status": "affected", "versionType": "git" }, { "version": "5640f7685831e088fe6c2e1f863a6805962f8e81", "lessThan": "5a9afcd827cafe14a95c9fcbded2c2d104f18dfc", "status": "affected", "versionType": "git" }, { "version": "5640f7685831e088fe6c2e1f863a6805962f8e81", "lessThan": "dacb5d8875cc6cd3a553363b4d6f06760fcbe70c", "status": "affected", "versionType": "git" } ] }, { "product": "Linux", "vendor": "Linux", "defaultStatus": "affected", "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git", "programFiles": [ "include/net/sock.h" ], "versions": [ { "version": "3.7", "status": "affected" }, { "version": "0", "lessThan": "3.7", "status": "unaffected", "versionType": "semver" }, { "version": "5.10.84", "lessThanOrEqual": "5.10.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.15.7", "lessThanOrEqual": "5.15.*", "status": "unaffected", "versionType": "semver" }, { "version": "5.16", "lessThanOrEqual": "*", "status": "unaffected", "versionType": "original_commit_for_fix" } ] } ], "cpeApplicability": [ { "nodes": [ { "operator": "OR", "negate": false, "cpeMatch": [ { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.7", "versionEndExcluding": "5.10.84" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.7", "versionEndExcluding": "5.15.7" }, { "vulnerable": true, "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "versionStartIncluding": "3.7", "versionEndExcluding": "5.16" } ] } ] } ], "references": [ { "url": "https://git.kernel.org/stable/c/c6f340a331fb72e5ac23a083de9c780e132ca3ae" }, { "url": "https://git.kernel.org/stable/c/5a9afcd827cafe14a95c9fcbded2c2d104f18dfc" }, { "url": "https://git.kernel.org/stable/c/dacb5d8875cc6cd3a553363b4d6f06760fcbe70c" } ], "title": "tcp: fix page frag corruption on page fault", "x_generator": { "engine": "bippy-1.2.0" } }, "adp": [ { "title": "CISA ADP Vulnrichment", "metrics": [ { "other": { "type": "ssvc", "content": { "id": "CVE-2021-47544", "role": "CISA Coordinator", "options": [ { "Exploitation": "none" }, { "Automatable": "no" }, { "Technical Impact": "partial" } ], "version": "2.0.3", "timestamp": "2024-05-28T17:06:35.022552Z" } } } ], "providerMetadata": { "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0", "shortName": "CISA-ADP", "dateUpdated": "2024-06-04T17:15:09.727Z" } }, { "providerMetadata": { "orgId": "af854a3a-2127-422b-91ae-364da2661108", "shortName": "CVE", "dateUpdated": "2024-08-04T05:39:59.619Z" }, "title": "CVE Program Container", "references": [ { "url": "https://git.kernel.org/stable/c/c6f340a331fb72e5ac23a083de9c780e132ca3ae", "tags": [ "x_transferred" ] }, { "url": "https://git.kernel.org/stable/c/5a9afcd827cafe14a95c9fcbded2c2d104f18dfc", "tags": [ "x_transferred" ] }, { "url": "https://git.kernel.org/stable/c/dacb5d8875cc6cd3a553363b4d6f06760fcbe70c", "tags": [ "x_transferred" ] } ] } ] } }