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CVE-2021-46987— btrfs: fix deadlock when cloning inline extents and using qgroups

EPSS 0.01% · P2
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I. Basic Information for CVE-2021-46987

Vulnerability Information
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Vulnerability Title
btrfs: fix deadlock when cloning inline extents and using qgroups
Source: NVD (National Vulnerability Database)
Vulnerability Description
In the Linux kernel, the following vulnerability has been resolved: btrfs: fix deadlock when cloning inline extents and using qgroups There are a few exceptional cases where cloning an inline extent needs to copy the inline extent data into a page of the destination inode. When this happens, we end up starting a transaction while having a dirty page for the destination inode and while having the range locked in the destination's inode iotree too. Because when reserving metadata space for a transaction we may need to flush existing delalloc in case there is not enough free space, we have a mechanism in place to prevent a deadlock, which was introduced in commit 3d45f221ce627d ("btrfs: fix deadlock when cloning inline extent and low on free metadata space"). However when using qgroups, a transaction also reserves metadata qgroup space, which can also result in flushing delalloc in case there is not enough available space at the moment. When this happens we deadlock, since flushing delalloc requires locking the file range in the inode's iotree and the range was already locked at the very beginning of the clone operation, before attempting to start the transaction. When this issue happens, stack traces like the following are reported: [72747.556262] task:kworker/u81:9 state:D stack: 0 pid: 225 ppid: 2 flags:0x00004000 [72747.556268] Workqueue: writeback wb_workfn (flush-btrfs-1142) [72747.556271] Call Trace: [72747.556273] __schedule+0x296/0x760 [72747.556277] schedule+0x3c/0xa0 [72747.556279] io_schedule+0x12/0x40 [72747.556284] __lock_page+0x13c/0x280 [72747.556287] ? generic_file_readonly_mmap+0x70/0x70 [72747.556325] extent_write_cache_pages+0x22a/0x440 [btrfs] [72747.556331] ? __set_page_dirty_nobuffers+0xe7/0x160 [72747.556358] ? set_extent_buffer_dirty+0x5e/0x80 [btrfs] [72747.556362] ? update_group_capacity+0x25/0x210 [72747.556366] ? cpumask_next_and+0x1a/0x20 [72747.556391] extent_writepages+0x44/0xa0 [btrfs] [72747.556394] do_writepages+0x41/0xd0 [72747.556398] __writeback_single_inode+0x39/0x2a0 [72747.556403] writeback_sb_inodes+0x1ea/0x440 [72747.556407] __writeback_inodes_wb+0x5f/0xc0 [72747.556410] wb_writeback+0x235/0x2b0 [72747.556414] ? get_nr_inodes+0x35/0x50 [72747.556417] wb_workfn+0x354/0x490 [72747.556420] ? newidle_balance+0x2c5/0x3e0 [72747.556424] process_one_work+0x1aa/0x340 [72747.556426] worker_thread+0x30/0x390 [72747.556429] ? create_worker+0x1a0/0x1a0 [72747.556432] kthread+0x116/0x130 [72747.556435] ? kthread_park+0x80/0x80 [72747.556438] ret_from_fork+0x1f/0x30 [72747.566958] Workqueue: btrfs-flush_delalloc btrfs_work_helper [btrfs] [72747.566961] Call Trace: [72747.566964] __schedule+0x296/0x760 [72747.566968] ? finish_wait+0x80/0x80 [72747.566970] schedule+0x3c/0xa0 [72747.566995] wait_extent_bit.constprop.68+0x13b/0x1c0 [btrfs] [72747.566999] ? finish_wait+0x80/0x80 [72747.567024] lock_extent_bits+0x37/0x90 [btrfs] [72747.567047] btrfs_invalidatepage+0x299/0x2c0 [btrfs] [72747.567051] ? find_get_pages_range_tag+0x2cd/0x380 [72747.567076] __extent_writepage+0x203/0x320 [btrfs] [72747.567102] extent_write_cache_pages+0x2bb/0x440 [btrfs] [72747.567106] ? update_load_avg+0x7e/0x5f0 [72747.567109] ? enqueue_entity+0xf4/0x6f0 [72747.567134] extent_writepages+0x44/0xa0 [btrfs] [72747.567137] ? enqueue_task_fair+0x93/0x6f0 [72747.567140] do_writepages+0x41/0xd0 [72747.567144] __filemap_fdatawrite_range+0xc7/0x100 [72747.567167] btrfs_run_delalloc_work+0x17/0x40 [btrfs] [72747.567195] btrfs_work_helper+0xc2/0x300 [btrfs] [72747.567200] process_one_work+0x1aa/0x340 [72747.567202] worker_thread+0x30/0x390 [72747.567205] ? create_worker+0x1a0/0x1a0 [72747.567208] kthread+0x116/0x130 [72747.567211] ? kthread_park+0x80/0x80 [72747.567214] ret_from_fork+0x1f/0x30 [72747.569686] task:fsstress state:D stack: ---truncated---
Source: NVD (National Vulnerability Database)
CVSS Information
N/A
Source: NVD (National Vulnerability Database)
Vulnerability Type
N/A
Source: NVD (National Vulnerability Database)
Vulnerability Title
Linux kernel 安全漏洞
Source: CNNVD (China National Vulnerability Database)
Vulnerability Description
Linux kernel是美国Linux基金会的开源操作系统Linux所使用的内核。 Linux kernel 存在安全漏洞，该漏洞源于在使用 qgroup 时会出现死锁情况。
Source: CNNVD (China National Vulnerability Database)
CVSS Information
N/A
Source: CNNVD (China National Vulnerability Database)
Vulnerability Type
N/A
Source: CNNVD (China National Vulnerability Database)

Affected Products

VendorProductAffected VersionsCPESubscribe
LinuxLinux c53e9653605dbf708f5be02902de51831be4b009 ~ f8fbbd06fab9b75dcd68d850fe318ac3bc128974 -
LinuxLinux 5.9 -

II. Public POCs for CVE-2021-46987

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III. Intelligence Information for CVE-2021-46987

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Same Patch Batch · Linux · 2024-02-28 · 86 CVEs total

CVE-2021-46997arm64: entry: always set GIC_PRIO_PSR_I_SET during entry
CVE-2021-47001xprtrdma: Fix cwnd update ordering
CVE-2021-46998ethernet:enic: Fix a use after free bug in enic_hard_start_xmit
CVE-2021-47000ceph: fix inode leak on getattr error in __fh_to_dentry
CVE-2021-47003dmaengine: idxd: Fix potential null dereference on pointer status
CVE-2021-47005PCI: endpoint: Fix NULL pointer dereference for ->get_features()
CVE-2021-47007f2fs: fix panic during f2fs_resize_fs()
CVE-2021-47006ARM: 9064/1: hw_breakpoint: Do not directly check the event's overflow_handler hook
CVE-2021-47009KEYS: trusted: Fix memory leak on object td
CVE-2021-47004f2fs: fix to avoid touching checkpointed data in get_victim()
CVE-2021-46999sctp: do asoc update earlier in sctp_sf_do_dupcook_a
CVE-2021-46995can: mcp251xfd: mcp251xfd_probe(): fix an error pointer dereference in probe
CVE-2021-46996netfilter: nftables: Fix a memleak from userdata error path in new objects
CVE-2021-46994can: mcp251x: fix resume from sleep before interface was brought up
CVE-2021-46992netfilter: nftables: avoid overflows in nft_hash_buckets()
CVE-2021-46993sched: Fix out-of-bound access in uclamp
CVE-2021-46990powerpc/64s: Fix crashes when toggling entry flush barrier
CVE-2021-46991i40e: Fix use-after-free in i40e_client_subtask()
CVE-2021-46989hfsplus: prevent corruption in shrinking truncate
CVE-2021-46988userfaultfd: release page in error path to avoid BUG_ON

Showing top 20 of 86 CVEs. View all on vendor page → →

IV. Related Vulnerabilities

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Same vendor: Linux

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