ghsa-w7cg-566v-rm5v
Vulnerability from github
Published
2024-04-17 12:32
Modified
2024-04-17 12:32
Details

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

nfs: fix panic when nfs4_ff_layout_prepare_ds() fails

We've been seeing the following panic in production

BUG: kernel NULL pointer dereference, address: 0000000000000065 PGD 2f485f067 P4D 2f485f067 PUD 2cc5d8067 PMD 0 RIP: 0010:ff_layout_cancel_io+0x3a/0x90 [nfs_layout_flexfiles] Call Trace: ? __die+0x78/0xc0 ? page_fault_oops+0x286/0x380 ? __rpc_execute+0x2c3/0x470 [sunrpc] ? rpc_new_task+0x42/0x1c0 [sunrpc] ? exc_page_fault+0x5d/0x110 ? asm_exc_page_fault+0x22/0x30 ? ff_layout_free_layoutreturn+0x110/0x110 [nfs_layout_flexfiles] ? ff_layout_cancel_io+0x3a/0x90 [nfs_layout_flexfiles] ? ff_layout_cancel_io+0x6f/0x90 [nfs_layout_flexfiles] pnfs_mark_matching_lsegs_return+0x1b0/0x360 [nfsv4] pnfs_error_mark_layout_for_return+0x9e/0x110 [nfsv4] ? ff_layout_send_layouterror+0x50/0x160 [nfs_layout_flexfiles] nfs4_ff_layout_prepare_ds+0x11f/0x290 [nfs_layout_flexfiles] ff_layout_pg_init_write+0xf0/0x1f0 [nfs_layout_flexfiles] __nfs_pageio_add_request+0x154/0x6c0 [nfs] nfs_pageio_add_request+0x26b/0x380 [nfs] nfs_do_writepage+0x111/0x1e0 [nfs] nfs_writepages_callback+0xf/0x30 [nfs] write_cache_pages+0x17f/0x380 ? nfs_pageio_init_write+0x50/0x50 [nfs] ? nfs_writepages+0x6d/0x210 [nfs] ? nfs_writepages+0x6d/0x210 [nfs] nfs_writepages+0x125/0x210 [nfs] do_writepages+0x67/0x220 ? generic_perform_write+0x14b/0x210 filemap_fdatawrite_wbc+0x5b/0x80 file_write_and_wait_range+0x6d/0xc0 nfs_file_fsync+0x81/0x170 [nfs] ? nfs_file_mmap+0x60/0x60 [nfs] __x64_sys_fsync+0x53/0x90 do_syscall_64+0x3d/0x90 entry_SYSCALL_64_after_hwframe+0x46/0xb0

Inspecting the core with drgn I was able to pull this

prog.crashed_thread().stack_trace()[0] #0 at 0xffffffffa079657a (ff_layout_cancel_io+0x3a/0x84) in ff_layout_cancel_io at fs/nfs/flexfilelayout/flexfilelayout.c:2021:27 prog.crashed_thread().stack_trace()[0]['idx'] (u32)1 prog.crashed_thread().stack_trace()[0]['flseg'].mirror_array[1].mirror_ds (struct nfs4_ff_layout_ds *)0xffffffffffffffed

This is clear from the stack trace, we call nfs4_ff_layout_prepare_ds() which could error out initializing the mirror_ds, and then we go to clean it all up and our check is only for if (!mirror->mirror_ds). This is inconsistent with the rest of the users of mirror_ds, which have

if (IS_ERR_OR_NULL(mirror_ds))

to keep from tripping over this exact scenario. Fix this up in ff_layout_cancel_io() to make sure we don't panic when we get an error. I also spot checked all the other instances of checking mirror_ds and we appear to be doing the correct checks everywhere, only unconditionally dereferencing mirror_ds when we know it would be valid.

Show details on source website


{
  "affected": [],
  "aliases": [
    "CVE-2024-26868"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2024-04-17T11:15:09Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnfs: fix panic when nfs4_ff_layout_prepare_ds() fails\n\nWe\u0027ve been seeing the following panic in production\n\nBUG: kernel NULL pointer dereference, address: 0000000000000065\nPGD 2f485f067 P4D 2f485f067 PUD 2cc5d8067 PMD 0\nRIP: 0010:ff_layout_cancel_io+0x3a/0x90 [nfs_layout_flexfiles]\nCall Trace:\n \u003cTASK\u003e\n ? __die+0x78/0xc0\n ? page_fault_oops+0x286/0x380\n ? __rpc_execute+0x2c3/0x470 [sunrpc]\n ? rpc_new_task+0x42/0x1c0 [sunrpc]\n ? exc_page_fault+0x5d/0x110\n ? asm_exc_page_fault+0x22/0x30\n ? ff_layout_free_layoutreturn+0x110/0x110 [nfs_layout_flexfiles]\n ? ff_layout_cancel_io+0x3a/0x90 [nfs_layout_flexfiles]\n ? ff_layout_cancel_io+0x6f/0x90 [nfs_layout_flexfiles]\n pnfs_mark_matching_lsegs_return+0x1b0/0x360 [nfsv4]\n pnfs_error_mark_layout_for_return+0x9e/0x110 [nfsv4]\n ? ff_layout_send_layouterror+0x50/0x160 [nfs_layout_flexfiles]\n nfs4_ff_layout_prepare_ds+0x11f/0x290 [nfs_layout_flexfiles]\n ff_layout_pg_init_write+0xf0/0x1f0 [nfs_layout_flexfiles]\n __nfs_pageio_add_request+0x154/0x6c0 [nfs]\n nfs_pageio_add_request+0x26b/0x380 [nfs]\n nfs_do_writepage+0x111/0x1e0 [nfs]\n nfs_writepages_callback+0xf/0x30 [nfs]\n write_cache_pages+0x17f/0x380\n ? nfs_pageio_init_write+0x50/0x50 [nfs]\n ? nfs_writepages+0x6d/0x210 [nfs]\n ? nfs_writepages+0x6d/0x210 [nfs]\n nfs_writepages+0x125/0x210 [nfs]\n do_writepages+0x67/0x220\n ? generic_perform_write+0x14b/0x210\n filemap_fdatawrite_wbc+0x5b/0x80\n file_write_and_wait_range+0x6d/0xc0\n nfs_file_fsync+0x81/0x170 [nfs]\n ? nfs_file_mmap+0x60/0x60 [nfs]\n __x64_sys_fsync+0x53/0x90\n do_syscall_64+0x3d/0x90\n entry_SYSCALL_64_after_hwframe+0x46/0xb0\n\nInspecting the core with drgn I was able to pull this\n\n  \u003e\u003e\u003e prog.crashed_thread().stack_trace()[0]\n  #0 at 0xffffffffa079657a (ff_layout_cancel_io+0x3a/0x84) in ff_layout_cancel_io at fs/nfs/flexfilelayout/flexfilelayout.c:2021:27\n  \u003e\u003e\u003e prog.crashed_thread().stack_trace()[0][\u0027idx\u0027]\n  (u32)1\n  \u003e\u003e\u003e prog.crashed_thread().stack_trace()[0][\u0027flseg\u0027].mirror_array[1].mirror_ds\n  (struct nfs4_ff_layout_ds *)0xffffffffffffffed\n\nThis is clear from the stack trace, we call nfs4_ff_layout_prepare_ds()\nwhich could error out initializing the mirror_ds, and then we go to\nclean it all up and our check is only for if (!mirror-\u003emirror_ds).  This\nis inconsistent with the rest of the users of mirror_ds, which have\n\n  if (IS_ERR_OR_NULL(mirror_ds))\n\nto keep from tripping over this exact scenario.  Fix this up in\nff_layout_cancel_io() to make sure we don\u0027t panic when we get an error.\nI also spot checked all the other instances of checking mirror_ds and we\nappear to be doing the correct checks everywhere, only unconditionally\ndereferencing mirror_ds when we know it would be valid.",
  "id": "GHSA-w7cg-566v-rm5v",
  "modified": "2024-04-17T12:32:04Z",
  "published": "2024-04-17T12:32:04Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2024-26868"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/31db25e3141b20e2a76a9f219eeca52e3cab126c"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/5ada9016b1217498fad876a3d5b07645cc955608"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/719fcafe07c12646691bd62d7f8d94d657fa0766"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/7ca651b4ec4a049f5a46a0e5ff921b86b91c47c5"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/dac068f164ad05b35e7c0be13f138c3f6adca58f"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}


Log in or create an account to share your comment.




Tags
Taxonomy of the tags.


Loading...

Loading...

Loading...
  • Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
  • Confirmed: The vulnerability is confirmed from an analyst perspective.
  • Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
  • Patched: This vulnerability was successfully patched by the user reporting the sighting.
  • Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
  • Not confirmed: The user expresses doubt about the veracity of the vulnerability.
  • Not patched: This vulnerability was not successfully patched by the user reporting the sighting.