{"uuid": "006da7fc-5cc2-47f9-82e4-c6f77db4d2af", "vulnerability_lookup_origin": "1a89b78e-f703-45f3-bb86-59eb712668bd", "author": "2a075640-a300-48a4-bb44-bc6130783b9b", "vulnerability": "CVE-2024-47736", "type": "published-proof-of-concept", "source": "https://t.me/DarkWebInformer_CVEAlerts/2125", "content": "\ud83d\udd17 DarkWebInformer.com - Cyber Threat Intelligence\n\ud83d\udccc CVE ID: CVE-2024-47736\n\ud83d\udd39 Description: In the Linux kernel, the following vulnerability has been resolved:\n\nerofs: handle overlapped pclusters out of crafted images properly\n\nsyzbot reported a task hang issue due to a deadlock case where it is\nwaiting for the folio lock of a cached folio that will be used for\ncache I/Os.\n\nAfter looking into the crafted fuzzed image, I found it's formed with\nseveral overlapped big pclusters as below:\n\n Ext:   logical offset   |  length :     physical offset    |  length\n   0:        0..   16384 |   16384 :     151552..    167936 |   16384\n   1:    16384..   32768 |   16384 :     155648..    172032 |   16384\n   2:    32768..   49152 |   16384 :  537223168.. 537239552 |   16384\n...\n\nHere, extent 0/1 are physically overlapped although it's entirely\n_impossible_ for normal filesystem images generated by mkfs.\n\nFirst, managed folios containing compressed data will be marked as\nup-to-date and then unlocked immediately (unlike in-place folios) when\ncompressed I/Os are complete.  If physical blocks are not submitted in\nthe incremental order, there should be separate BIOs to avoid dependency\nissues.  However, the current code mis-arranges z_erofs_fill_bio_vec()\nand BIO submission which causes unexpected BIO waits.\n\nSecond, managed folios will be connected to their own pclusters for\nefficient inter-queries.  However, this is somewhat hard to implement\neasily if overlapped big pclusters exist.  Again, these only appear in\nfuzzed images so let's simply fall back to temporary short-lived pages\nfor correctness.\n\nAdditionally, it justifies that referenced managed folios cannot be\ntruncated for now and reverts part of commit 2080ca1ed3e4 (\"erofs: tidy\nup `struct z_erofs_bvec`\") for simplicity although it shouldn't be any\ndifference.\n\ud83d\udccf Published: 2024-10-21T12:14:06.530Z\n\ud83d\udccf Modified: 2025-01-17T13:26:59.000Z\n\ud83d\udd17 References:\n1. https://git.kernel.org/stable/c/1bf7e414cac303c9aec1be67872e19be8b64980c\n2. https://git.kernel.org/stable/c/b9b30af0e86ffb485301ecd83b9129c9dfb7ebf8\n3. https://git.kernel.org/stable/c/9cfa199bcbbbba31cbf97b2786f44f4464f3f29a\n4. https://git.kernel.org/stable/c/9e2f9d34dd12e6e5b244ec488bcebd0c2d566c50", "creation_timestamp": "2025-01-17T13:56:47.000000Z"}