ghsa-gcv4-6hmh-xhwc
Vulnerability from github
Published
2024-10-21 18:30
Modified
2024-10-24 21:31
Severity ?
7.8 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Details

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

btrfs: send: fix buffer overflow detection when copying path to cache entry

Starting with commit c0247d289e73 ("btrfs: send: annotate struct name_cache_entry with __counted_by()") we annotated the variable length array "name" from the name_cache_entry structure with __counted_by() to improve overflow detection. However that alone was not correct, because the length of that array does not match the "name_len" field - it matches that plus 1 to include the NUL string terminator, so that makes a fortified kernel think there's an overflow and report a splat like this:

strcpy: detected buffer overflow: 20 byte write of buffer size 19 WARNING: CPU: 3 PID: 3310 at __fortify_report+0x45/0x50 CPU: 3 UID: 0 PID: 3310 Comm: btrfs Not tainted 6.11.0-prnet #1 Hardware name: CompuLab Ltd. sbc-ihsw/Intense-PC2 (IPC2), BIOS IPC2_3.330.7 X64 03/15/2018 RIP: 0010:__fortify_report+0x45/0x50 Code: 48 8b 34 (...) RSP: 0018:ffff97ebc0d6f650 EFLAGS: 00010246 RAX: 7749924ef60fa600 RBX: ffff8bf5446a521a RCX: 0000000000000027 RDX: 00000000ffffdfff RSI: ffff97ebc0d6f548 RDI: ffff8bf84e7a1cc8 RBP: ffff8bf548574080 R08: ffffffffa8c40e10 R09: 0000000000005ffd R10: 0000000000000004 R11: ffffffffa8c70e10 R12: ffff8bf551eef400 R13: 0000000000000000 R14: 0000000000000013 R15: 00000000000003a8 FS: 00007fae144de8c0(0000) GS:ffff8bf84e780000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fae14691690 CR3: 00000001027a2003 CR4: 00000000001706f0 Call Trace: ? __warn+0x12a/0x1d0 ? __fortify_report+0x45/0x50 ? report_bug+0x154/0x1c0 ? handle_bug+0x42/0x70 ? exc_invalid_op+0x1a/0x50 ? asm_exc_invalid_op+0x1a/0x20 ? __fortify_report+0x45/0x50 __fortify_panic+0x9/0x10 __get_cur_name_and_parent+0x3bc/0x3c0 get_cur_path+0x207/0x3b0 send_extent_data+0x709/0x10d0 ? find_parent_nodes+0x22df/0x25d0 ? mas_nomem+0x13/0x90 ? mtree_insert_range+0xa5/0x110 ? btrfs_lru_cache_store+0x5f/0x1e0 ? iterate_extent_inodes+0x52d/0x5a0 process_extent+0xa96/0x11a0 ? __pfx_lookup_backref_cache+0x10/0x10 ? __pfx_store_backref_cache+0x10/0x10 ? __pfx_iterate_backrefs+0x10/0x10 ? __pfx_check_extent_item+0x10/0x10 changed_cb+0x6fa/0x930 ? tree_advance+0x362/0x390 ? memcmp_extent_buffer+0xd7/0x160 send_subvol+0xf0a/0x1520 btrfs_ioctl_send+0x106b/0x11d0 ? __pfxcloneroot_cmp_sort+0x10/0x10 _btrfs_ioctl_send+0x1ac/0x240 btrfs_ioctl+0x75b/0x850 se_sys_ioctl+0xca/0x150 do_syscall_64+0x85/0x160 ? __count_memcg_events+0x69/0x100 ? handle_mm_fault+0x1327/0x15c0 ? __se_sys_rt_sigprocmask+0xf1/0x180 ? syscall_exit_to_user_mode+0x75/0xa0 ? do_syscall_64+0x91/0x160 ? do_user_addr_fault+0x21d/0x630 entry_SYSCALL_64_after_hwframe+0x76/0x7e RIP: 0033:0x7fae145eeb4f Code: 00 48 89 (...) RSP: 002b:00007ffdf1cb09b0 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 00007fae145eeb4f RDX: 00007ffdf1cb0ad0 RSI: 0000000040489426 RDI: 0000000000000004 RBP: 00000000000078fe R08: 00007fae144006c0 R09: 00007ffdf1cb0927 R10: 0000000000000008 R11: 0000000000000246 R12: 00007ffdf1cb1ce8 R13: 0000000000000003 R14: 000055c499fab2e0 R15: 0000000000000004

Fix this by not storing the NUL string terminator since we don't actually need it for name cache entries, this way "name_len" corresponds to the actual size of the "name" array. This requires marking the "name" array field with __nonstring and using memcpy() instead of strcpy() as recommended by the guidelines at:

https://github.com/KSPP/linux/issues/90

Show details on source website

To clipboard 

{
   affected: [],
   aliases: [
      "CVE-2024-49869",
   ],
   database_specific: {
      cwe_ids: [
         "CWE-120",
      ],
      github_reviewed: false,
      github_reviewed_at: null,
      nvd_published_at: "2024-10-21T18:15:08Z",
      severity: "HIGH",
   },
   details: "In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: send: fix buffer overflow detection when copying path to cache entry\n\nStarting with commit c0247d289e73 (\"btrfs: send: annotate struct\nname_cache_entry with __counted_by()\") we annotated the variable length\narray \"name\" from the name_cache_entry structure with __counted_by() to\nimprove overflow detection. However that alone was not correct, because\nthe length of that array does not match the \"name_len\" field - it matches\nthat plus 1 to include the NUL string terminator, so that makes a\nfortified kernel think there's an overflow and report a splat like this:\n\n  strcpy: detected buffer overflow: 20 byte write of buffer size 19\n  WARNING: CPU: 3 PID: 3310 at __fortify_report+0x45/0x50\n  CPU: 3 UID: 0 PID: 3310 Comm: btrfs Not tainted 6.11.0-prnet #1\n  Hardware name: CompuLab Ltd.  sbc-ihsw/Intense-PC2 (IPC2), BIOS IPC2_3.330.7 X64 03/15/2018\n  RIP: 0010:__fortify_report+0x45/0x50\n  Code: 48 8b 34 (...)\n  RSP: 0018:ffff97ebc0d6f650 EFLAGS: 00010246\n  RAX: 7749924ef60fa600 RBX: ffff8bf5446a521a RCX: 0000000000000027\n  RDX: 00000000ffffdfff RSI: ffff97ebc0d6f548 RDI: ffff8bf84e7a1cc8\n  RBP: ffff8bf548574080 R08: ffffffffa8c40e10 R09: 0000000000005ffd\n  R10: 0000000000000004 R11: ffffffffa8c70e10 R12: ffff8bf551eef400\n  R13: 0000000000000000 R14: 0000000000000013 R15: 00000000000003a8\n  FS:  00007fae144de8c0(0000) GS:ffff8bf84e780000(0000) knlGS:0000000000000000\n  CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033\n  CR2: 00007fae14691690 CR3: 00000001027a2003 CR4: 00000000001706f0\n  Call Trace:\n   <TASK>\n   ? __warn+0x12a/0x1d0\n   ? __fortify_report+0x45/0x50\n   ? report_bug+0x154/0x1c0\n   ? handle_bug+0x42/0x70\n   ? exc_invalid_op+0x1a/0x50\n   ? asm_exc_invalid_op+0x1a/0x20\n   ? __fortify_report+0x45/0x50\n   __fortify_panic+0x9/0x10\n  __get_cur_name_and_parent+0x3bc/0x3c0\n   get_cur_path+0x207/0x3b0\n   send_extent_data+0x709/0x10d0\n   ? find_parent_nodes+0x22df/0x25d0\n   ? mas_nomem+0x13/0x90\n   ? mtree_insert_range+0xa5/0x110\n   ? btrfs_lru_cache_store+0x5f/0x1e0\n   ? iterate_extent_inodes+0x52d/0x5a0\n   process_extent+0xa96/0x11a0\n   ? __pfx_lookup_backref_cache+0x10/0x10\n   ? __pfx_store_backref_cache+0x10/0x10\n   ? __pfx_iterate_backrefs+0x10/0x10\n   ? __pfx_check_extent_item+0x10/0x10\n   changed_cb+0x6fa/0x930\n   ? tree_advance+0x362/0x390\n   ? memcmp_extent_buffer+0xd7/0x160\n   send_subvol+0xf0a/0x1520\n   btrfs_ioctl_send+0x106b/0x11d0\n   ? __pfx___clone_root_cmp_sort+0x10/0x10\n   _btrfs_ioctl_send+0x1ac/0x240\n   btrfs_ioctl+0x75b/0x850\n   __se_sys_ioctl+0xca/0x150\n   do_syscall_64+0x85/0x160\n   ? __count_memcg_events+0x69/0x100\n   ? handle_mm_fault+0x1327/0x15c0\n   ? __se_sys_rt_sigprocmask+0xf1/0x180\n   ? syscall_exit_to_user_mode+0x75/0xa0\n   ? do_syscall_64+0x91/0x160\n   ? do_user_addr_fault+0x21d/0x630\n  entry_SYSCALL_64_after_hwframe+0x76/0x7e\n  RIP: 0033:0x7fae145eeb4f\n  Code: 00 48 89 (...)\n  RSP: 002b:00007ffdf1cb09b0 EFLAGS: 00000246 ORIG_RAX: 0000000000000010\n  RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 00007fae145eeb4f\n  RDX: 00007ffdf1cb0ad0 RSI: 0000000040489426 RDI: 0000000000000004\n  RBP: 00000000000078fe R08: 00007fae144006c0 R09: 00007ffdf1cb0927\n  R10: 0000000000000008 R11: 0000000000000246 R12: 00007ffdf1cb1ce8\n  R13: 0000000000000003 R14: 000055c499fab2e0 R15: 0000000000000004\n   </TASK>\n\nFix this by not storing the NUL string terminator since we don't actually\nneed it for name cache entries, this way \"name_len\" corresponds to the\nactual size of the \"name\" array. This requires marking the \"name\" array\nfield with __nonstring and using memcpy() instead of strcpy() as\nrecommended by the guidelines at:\n\n   https://github.com/KSPP/linux/issues/90",
   id: "GHSA-gcv4-6hmh-xhwc",
   modified: "2024-10-24T21:31:01Z",
   published: "2024-10-21T18:30:56Z",
   references: [
      {
         type: "ADVISORY",
         url: "https://nvd.nist.gov/vuln/detail/CVE-2024-49869",
      },
      {
         type: "WEB",
         url: "https://git.kernel.org/stable/c/843738ede6cb8b959fb22591fcbabe8b456d7216",
      },
      {
         type: "WEB",
         url: "https://git.kernel.org/stable/c/96c6ca71572a3556ed0c37237305657ff47174b7",
      },
   ],
   schema_version: "1.4.0",
   severity: [
      {
         score: "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
         type: "CVSS_V3",
      },
   ],
}


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