ghsa-c754-vqmv-w93f
Vulnerability from github
Published
2025-07-09 12:31
Modified
2025-07-17 18:31
Details

In the Linux kernel, the following vulnerability has been resolved:

bcache: fix NULL pointer in cache_set_flush()

  1. LINE#1794 - LINE#1887 is some codes about function of bch_cache_set_alloc().
  2. LINE#2078 - LINE#2142 is some codes about function of register_cache_set().
  3. register_cache_set() will call bch_cache_set_alloc() in LINE#2098.

1794 struct cache_set bch_cache_set_alloc(struct cache_sb sb) 1795 { ... 1860 if (!(c->devices = kcalloc(c->nr_uuids, sizeof(void ), GFP_KERNEL)) || 1861 mempool_init_slab_pool(&c->search, 32, bch_search_cache) || 1862 mempool_init_kmalloc_pool(&c->bio_meta, 2, 1863 sizeof(struct bbio) + sizeof(struct bio_vec) * 1864 bucket_pages(c)) || 1865 mempool_init_kmalloc_pool(&c->fill_iter, 1, iter_size) || 1866 bioset_init(&c->bio_split, 4, offsetof(struct bbio, bio), 1867 BIOSET_NEED_BVECS|BIOSET_NEED_RESCUER) || 1868 !(c->uuids = alloc_bucket_pages(GFP_KERNEL, c)) || 1869 !(c->moving_gc_wq = alloc_workqueue("bcache_gc", 1870 WQ_MEM_RECLAIM, 0)) || 1871 bch_journal_alloc(c) || 1872 bch_btree_cache_alloc(c) || 1873 bch_open_buckets_alloc(c) || 1874 bch_bset_sort_state_init(&c->sort, ilog2(c->btree_pages))) 1875 goto err; ^^^^^^^^ 1876 ... 1883 return c; 1884 err: 1885 bch_cache_set_unregister(c); ^^^^^^^^^^^^^^^^^^^^^^^^^^^ 1886 return NULL; 1887 } ... 2078 static const char register_cache_set(struct cache *ca) 2079 { ... 2098 c = bch_cache_set_alloc(&ca->sb); 2099 if (!c) 2100 return err; ^^^^^^^^^^ ... 2128 ca->set = c; 2129 ca->set->cache[ca->sb.nr_this_dev] = ca; ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ... 2138 return NULL; 2139 err: 2140 bch_cache_set_unregister(c); 2141 return err; 2142 }

(1) If LINE#1860 - LINE#1874 is true, then do 'goto err'(LINE#1875) and call bch_cache_set_unregister()(LINE#1885). (2) As (1) return NULL(LINE#1886), LINE#2098 - LINE#2100 would return. (3) As (2) has returned, LINE#2128 - LINE#2129 would do not give the value to c->cache[], it means that c->cache[] is NULL.

LINE#1624 - LINE#1665 is some codes about function of cache_set_flush(). As (1), in LINE#1885 call bch_cache_set_unregister() ---> bch_cache_set_stop() ---> closure_queue() -.-> cache_set_flush() (as below LINE#1624)

1624 static void cache_set_flush(struct closure *cl) 1625 { ... 1654 for_each_cache(ca, c, i) 1655 if (ca->alloc_thread) ^^ 1656 kthread_stop(ca->alloc_thread); ... 1665 }

(4) In LINE#1655 ca is NULL(see (3)) in cache_set_flush() then the kernel crash occurred as below: [ 846.712887] bcache: register_cache() error drbd6: cannot allocate memory [ 846.713242] bcache: register_bcache() error : failed to register device [ 846.713336] bcache: cache_set_free() Cache set 2f84bdc1-498a-4f2f-98a7-01946bf54287 unregistered [ 846.713768] BUG: unable to handle kernel NULL pointer dereference at 00000000000009f8 [ 846.714790] PGD 0 P4D 0 [ 846.715129] Oops: 0000 [#1] SMP PTI [ 846.715472] CPU: 19 PID: 5057 Comm: kworker/19:16 Kdump: loaded Tainted: G OE --------- - - 4.18.0-147.5.1.el8_1.5es.3.x86_64 #1 [ 846.716082] Hardware name: ESPAN GI-25212/X11DPL-i, BIOS 2.1 06/15/2018 [ 846.716451] Workqueue: events cache_set_flush [bcache] [ 846.716808] RIP: 0010:cache_set_flush+0xc9/0x1b0 [bcache] [ 846.717155] Code: 00 4c 89 a5 b0 03 00 00 48 8b 85 68 f6 ff ff a8 08 0f 84 88 00 00 00 31 db 66 83 bd 3c f7 ff ff 00 48 8b 85 48 ff ff ff 74 28 <48> 8b b8 f8 09 00 0 ---truncated---

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{
  "affected": [],
  "aliases": [
    "CVE-2025-38263"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2025-07-09T11:15:28Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nbcache: fix NULL pointer in cache_set_flush()\n\n1. LINE#1794 - LINE#1887 is some codes about function of\n   bch_cache_set_alloc().\n2. LINE#2078 - LINE#2142 is some codes about function of\n   register_cache_set().\n3. register_cache_set() will call bch_cache_set_alloc() in LINE#2098.\n\n 1794 struct cache_set *bch_cache_set_alloc(struct cache_sb *sb)\n 1795 {\n ...\n 1860         if (!(c-\u003edevices = kcalloc(c-\u003enr_uuids, sizeof(void *), GFP_KERNEL)) ||\n 1861             mempool_init_slab_pool(\u0026c-\u003esearch, 32, bch_search_cache) ||\n 1862             mempool_init_kmalloc_pool(\u0026c-\u003ebio_meta, 2,\n 1863                                 sizeof(struct bbio) + sizeof(struct bio_vec) *\n 1864                                 bucket_pages(c)) ||\n 1865             mempool_init_kmalloc_pool(\u0026c-\u003efill_iter, 1, iter_size) ||\n 1866             bioset_init(\u0026c-\u003ebio_split, 4, offsetof(struct bbio, bio),\n 1867                         BIOSET_NEED_BVECS|BIOSET_NEED_RESCUER) ||\n 1868             !(c-\u003euuids = alloc_bucket_pages(GFP_KERNEL, c)) ||\n 1869             !(c-\u003emoving_gc_wq = alloc_workqueue(\"bcache_gc\",\n 1870                                                 WQ_MEM_RECLAIM, 0)) ||\n 1871             bch_journal_alloc(c) ||\n 1872             bch_btree_cache_alloc(c) ||\n 1873             bch_open_buckets_alloc(c) ||\n 1874             bch_bset_sort_state_init(\u0026c-\u003esort, ilog2(c-\u003ebtree_pages)))\n 1875                 goto err;\n                      ^^^^^^^^\n 1876\n ...\n 1883         return c;\n 1884 err:\n 1885         bch_cache_set_unregister(c);\n              ^^^^^^^^^^^^^^^^^^^^^^^^^^^\n 1886         return NULL;\n 1887 }\n ...\n 2078 static const char *register_cache_set(struct cache *ca)\n 2079 {\n ...\n 2098         c = bch_cache_set_alloc(\u0026ca-\u003esb);\n 2099         if (!c)\n 2100                 return err;\n                      ^^^^^^^^^^\n ...\n 2128         ca-\u003eset = c;\n 2129         ca-\u003eset-\u003ecache[ca-\u003esb.nr_this_dev] = ca;\n              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^\n ...\n 2138         return NULL;\n 2139 err:\n 2140         bch_cache_set_unregister(c);\n 2141         return err;\n 2142 }\n\n(1) If LINE#1860 - LINE#1874 is true, then do \u0027goto err\u0027(LINE#1875) and\n    call bch_cache_set_unregister()(LINE#1885).\n(2) As (1) return NULL(LINE#1886), LINE#2098 - LINE#2100 would return.\n(3) As (2) has returned, LINE#2128 - LINE#2129 would do *not* give the\n    value to c-\u003ecache[], it means that c-\u003ecache[] is NULL.\n\nLINE#1624 - LINE#1665 is some codes about function of cache_set_flush().\nAs (1), in LINE#1885 call\nbch_cache_set_unregister()\n---\u003e bch_cache_set_stop()\n     ---\u003e closure_queue()\n          -.-\u003e cache_set_flush() (as below LINE#1624)\n\n 1624 static void cache_set_flush(struct closure *cl)\n 1625 {\n ...\n 1654         for_each_cache(ca, c, i)\n 1655                 if (ca-\u003ealloc_thread)\n                          ^^\n 1656                         kthread_stop(ca-\u003ealloc_thread);\n ...\n 1665 }\n\n(4) In LINE#1655 ca is NULL(see (3)) in cache_set_flush() then the\n    kernel crash occurred as below:\n[  846.712887] bcache: register_cache() error drbd6: cannot allocate memory\n[  846.713242] bcache: register_bcache() error : failed to register device\n[  846.713336] bcache: cache_set_free() Cache set 2f84bdc1-498a-4f2f-98a7-01946bf54287 unregistered\n[  846.713768] BUG: unable to handle kernel NULL pointer dereference at 00000000000009f8\n[  846.714790] PGD 0 P4D 0\n[  846.715129] Oops: 0000 [#1] SMP PTI\n[  846.715472] CPU: 19 PID: 5057 Comm: kworker/19:16 Kdump: loaded Tainted: G           OE    --------- -  - 4.18.0-147.5.1.el8_1.5es.3.x86_64 #1\n[  846.716082] Hardware name: ESPAN GI-25212/X11DPL-i, BIOS 2.1 06/15/2018\n[  846.716451] Workqueue: events cache_set_flush [bcache]\n[  846.716808] RIP: 0010:cache_set_flush+0xc9/0x1b0 [bcache]\n[  846.717155] Code: 00 4c 89 a5 b0 03 00 00 48 8b 85 68 f6 ff ff a8 08 0f 84 88 00 00 00 31 db 66 83 bd 3c f7 ff ff 00 48 8b 85 48 ff ff ff 74 28 \u003c48\u003e 8b b8 f8 09 00 0\n---truncated---",
  "id": "GHSA-c754-vqmv-w93f",
  "modified": "2025-07-17T18:31:12Z",
  "published": "2025-07-09T12:31:35Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-38263"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/1e46ed947ec658f89f1a910d880cd05e42d3763e"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/1f25f2d3fa29325320c19a30abf787e0bd5fc91b"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/3f9e128186c99a117e304f1dce6d0b9e50c63cd8"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/553f560e0a74a7008ad9dba05c3fd05da296befb"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/667c3f52373ff5354cb3543e27237eb7df7b2333"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/c4f5e7e417034b05f5d2f5fa9a872db897da69bd"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/d54681938b777488e5dfb781b566d16adad991de"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}


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