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ubuntucveUbuntu.comUB:CVE-2024-36027
HistoryMay 30, 2024 - 12:00 a.m.

CVE-2024-36027

2024-05-3000:00:00
ubuntu.com
ubuntu.com
btrfs
linux kernel
vulnerability
fs corrupted
buffer

7.4 High

AI Score

Confidence

High

0.0004 Low

EPSS

Percentile

9.1%

In the Linux kernel, the following vulnerability has been resolved:
btrfs: zoned: do not flag ZEROOUT on non-dirty extent buffer
Btrfs clears the content of an extent buffer marked as
EXTENT_BUFFER_ZONED_ZEROOUT before the bio submission. This mechanism is
introduced to prevent a write hole of an extent buffer, which is once
allocated, marked dirty, but turns out unnecessary and cleaned up within
one transaction operation.
Currently, btrfs_clear_buffer_dirty() marks the extent buffer as
EXTENT_BUFFER_ZONED_ZEROOUT, and skips the entry function. If this call
happens while the buffer is under IO (with the WRITEBACK flag set,
without the DIRTY flag), we can add the ZEROOUT flag and clear the
buffer’s content just before a bio submission. As a result:

  1. it can lead to adding faulty delayed reference item which leads to a
    FS corrupted (EUCLEAN) error, and
  2. it writes out cleared tree node on disk
    The former issue is previously discussed in [1]. The corruption happens
    when it runs a delayed reference update. So, on-disk data is safe.
    [1]
    https://lore.kernel.org/linux-btrfs/3f4f2a0ff1a6c818050434288925bdcf3cd719e5.1709124777.git.naohiro.aota@wdc.com/
    The latter one can reach on-disk data. But, as that node is already
    processed by btrfs_clear_buffer_dirty(), that will be invalidated in the
    next transaction commit anyway. So, the chance of hitting the corruption
    is relatively small.
    Anyway, we should skip flagging ZEROOUT on a non-DIRTY extent buffer, to
    keep the content under IO intact.

7.4 High

AI Score

Confidence

High

0.0004 Low

EPSS

Percentile

9.1%