ghsa-pw8w-hq42-r2hw
Vulnerability from github
In the Linux kernel, the following vulnerability has been resolved:
btrfs: fix race between direct IO write and fsync when using same fd
If we have 2 threads that are using the same file descriptor and one of them is doing direct IO writes while the other is doing fsync, we have a race where we can end up either:
1) Attempt a fsync without holding the inode's lock, triggering an assertion failures when assertions are enabled;
2) Do an invalid memory access from the fsync task because the file private points to memory allocated on stack by the direct IO task and it may be used by the fsync task after the stack was destroyed.
The race happens like this:
1) A user space program opens a file descriptor with O_DIRECT;
2) The program spawns 2 threads using libpthread for example;
3) One of the threads uses the file descriptor to do direct IO writes, while the other calls fsync using the same file descriptor.
4) Call task A the thread doing direct IO writes and task B the thread doing fsyncs;
5) Task A does a direct IO write, and at btrfs_direct_write() sets the file's private to an on stack allocated private with the member 'fsync_skip_inode_lock' set to true;
6) Task B enters btrfs_sync_file() and sees that there's a private structure associated to the file which has 'fsync_skip_inode_lock' set to true, so it skips locking the inode's VFS lock;
7) Task A completes the direct IO write, and resets the file's private to NULL since it had no prior private and our private was stack allocated. Then it unlocks the inode's VFS lock;
8) Task B enters btrfs_get_ordered_extents_for_logging(), then the assertion that checks the inode's VFS lock is held fails, since task B never locked it and task A has already unlocked it.
The stack trace produced is the following:
assertion failed: inode_is_locked(&inode->vfs_inode), in fs/btrfs/ordered-data.c:983
------------[ cut here ]------------
kernel BUG at fs/btrfs/ordered-data.c:983!
Oops: invalid opcode: 0000 [#1] PREEMPT SMP PTI
CPU: 9 PID: 5072 Comm: worker Tainted: G U OE 6.10.5-1-default #1 openSUSE Tumbleweed 69f48d427608e1c09e60ea24c6c55e2ca1b049e8
Hardware name: Acer Predator PH315-52/Covini_CFS, BIOS V1.12 07/28/2020
RIP: 0010:btrfs_get_ordered_extents_for_logging.cold+0x1f/0x42 [btrfs]
Code: 50 d6 86 c0 e8 (...)
RSP: 0018:ffff9e4a03dcfc78 EFLAGS: 00010246
RAX: 0000000000000054 RBX: ffff9078a9868e98 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffff907dce4a7800 RDI: ffff907dce4a7800
RBP: ffff907805518800 R08: 0000000000000000 R09: ffff9e4a03dcfb38
R10: ffff9e4a03dcfb30 R11: 0000000000000003 R12: ffff907684ae7800
R13: 0000000000000001 R14: ffff90774646b600 R15: 0000000000000000
FS: 00007f04b96006c0(0000) GS:ffff907dce480000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f32acbfc000 CR3: 00000001fd4fa005 CR4: 00000000003726f0
Call Trace:
{
"affected": [],
"aliases": [
"CVE-2024-46734"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2024-09-18T08:15:02Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: fix race between direct IO write and fsync when using same fd\n\nIf we have 2 threads that are using the same file descriptor and one of\nthem is doing direct IO writes while the other is doing fsync, we have a\nrace where we can end up either:\n\n1) Attempt a fsync without holding the inode\u0027s lock, triggering an\n assertion failures when assertions are enabled;\n\n2) Do an invalid memory access from the fsync task because the file private\n points to memory allocated on stack by the direct IO task and it may be\n used by the fsync task after the stack was destroyed.\n\nThe race happens like this:\n\n1) A user space program opens a file descriptor with O_DIRECT;\n\n2) The program spawns 2 threads using libpthread for example;\n\n3) One of the threads uses the file descriptor to do direct IO writes,\n while the other calls fsync using the same file descriptor.\n\n4) Call task A the thread doing direct IO writes and task B the thread\n doing fsyncs;\n\n5) Task A does a direct IO write, and at btrfs_direct_write() sets the\n file\u0027s private to an on stack allocated private with the member\n \u0027fsync_skip_inode_lock\u0027 set to true;\n\n6) Task B enters btrfs_sync_file() and sees that there\u0027s a private\n structure associated to the file which has \u0027fsync_skip_inode_lock\u0027 set\n to true, so it skips locking the inode\u0027s VFS lock;\n\n7) Task A completes the direct IO write, and resets the file\u0027s private to\n NULL since it had no prior private and our private was stack allocated.\n Then it unlocks the inode\u0027s VFS lock;\n\n8) Task B enters btrfs_get_ordered_extents_for_logging(), then the\n assertion that checks the inode\u0027s VFS lock is held fails, since task B\n never locked it and task A has already unlocked it.\n\nThe stack trace produced is the following:\n\n assertion failed: inode_is_locked(\u0026inode-\u003evfs_inode), in fs/btrfs/ordered-data.c:983\n ------------[ cut here ]------------\n kernel BUG at fs/btrfs/ordered-data.c:983!\n Oops: invalid opcode: 0000 [#1] PREEMPT SMP PTI\n CPU: 9 PID: 5072 Comm: worker Tainted: G U OE 6.10.5-1-default #1 openSUSE Tumbleweed 69f48d427608e1c09e60ea24c6c55e2ca1b049e8\n Hardware name: Acer Predator PH315-52/Covini_CFS, BIOS V1.12 07/28/2020\n RIP: 0010:btrfs_get_ordered_extents_for_logging.cold+0x1f/0x42 [btrfs]\n Code: 50 d6 86 c0 e8 (...)\n RSP: 0018:ffff9e4a03dcfc78 EFLAGS: 00010246\n RAX: 0000000000000054 RBX: ffff9078a9868e98 RCX: 0000000000000000\n RDX: 0000000000000000 RSI: ffff907dce4a7800 RDI: ffff907dce4a7800\n RBP: ffff907805518800 R08: 0000000000000000 R09: ffff9e4a03dcfb38\n R10: ffff9e4a03dcfb30 R11: 0000000000000003 R12: ffff907684ae7800\n R13: 0000000000000001 R14: ffff90774646b600 R15: 0000000000000000\n FS: 00007f04b96006c0(0000) GS:ffff907dce480000(0000) knlGS:0000000000000000\n CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033\n CR2: 00007f32acbfc000 CR3: 00000001fd4fa005 CR4: 00000000003726f0\n Call Trace:\n \u003cTASK\u003e\n ? __die_body.cold+0x14/0x24\n ? die+0x2e/0x50\n ? do_trap+0xca/0x110\n ? do_error_trap+0x6a/0x90\n ? btrfs_get_ordered_extents_for_logging.cold+0x1f/0x42 [btrfs bb26272d49b4cdc847cf3f7faadd459b62caee9a]\n ? exc_invalid_op+0x50/0x70\n ? btrfs_get_ordered_extents_for_logging.cold+0x1f/0x42 [btrfs bb26272d49b4cdc847cf3f7faadd459b62caee9a]\n ? asm_exc_invalid_op+0x1a/0x20\n ? btrfs_get_ordered_extents_for_logging.cold+0x1f/0x42 [btrfs bb26272d49b4cdc847cf3f7faadd459b62caee9a]\n ? btrfs_get_ordered_extents_for_logging.cold+0x1f/0x42 [btrfs bb26272d49b4cdc847cf3f7faadd459b62caee9a]\n btrfs_sync_file+0x21a/0x4d0 [btrfs bb26272d49b4cdc847cf3f7faadd459b62caee9a]\n ? __seccomp_filter+0x31d/0x4f0\n __x64_sys_fdatasync+0x4f/0x90\n do_syscall_64+0x82/0x160\n ? do_futex+0xcb/0x190\n ? __x64_sys_futex+0x10e/0x1d0\n ? switch_fpu_return+0x4f/0xd0\n ? syscall_exit_to_user_mode+0x72/0x220\n ? do_syscall_64+0x8e/0x160\n ? syscall_exit_to_user_mod\n---truncated---",
"id": "GHSA-pw8w-hq42-r2hw",
"modified": "2024-09-18T09:30:36Z",
"published": "2024-09-18T09:30:36Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2024-46734"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/01681aa609b5f110502f56c4e3b2938efcf4a5bc"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/7b5595f33c3c273613b590892a578d78186bb400"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/cd3087582e4fa36e89be4e6f859e75a4400292b4"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/cd9253c23aedd61eb5ff11f37a36247cd46faf86"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/d116a0b0e02f395cedfb8c725bd67480aa7c428c"
}
],
"schema_version": "1.4.0",
"severity": []
}
Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
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