{"dataType":"CVE_RECORD","dataVersion":"5.1","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":"2025-05-04T07:13:12.226Z"},"containers":{"cna":{"providerMetadata":{"orgId":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","shortName":"Linux","dateUpdated":"2025-05-04T07:13:12.226Z"},"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)"}],"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"]}]}]}}