Description

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

nilfs2: fix null-ptr-deref in block_dirty_buffer tracepoint

When using the "block:block_dirty_buffer" tracepoint, mark_buffer_dirty()
may cause a NULL pointer dereference, or a general protection fault when
KASAN is enabled.

This happens because, since the tracepoint was added in
mark_buffer_dirty(), it references the dev_t member bh->b_bdev->bd_dev
regardless of whether the buffer head has a pointer to a block_device
structure.

In the current implementation, nilfs_grab_buffer(), which grabs a buffer
to read (or create) a block of metadata, including b-tree node blocks,
does not set the block device, but instead does so only if the buffer is
not in the "uptodate" state for each of its caller block reading
functions. However, if the uptodate flag is set on a folio/page, and the
buffer heads are detached from it by try_to_free_buffers(), and new buffer
heads are then attached by create_empty_buffers(), the uptodate flag may
be restored to each buffer without the block device being set to
bh->b_bdev, and mark_buffer_dirty() may be called later in that state,
resulting in the bug mentioned above.

Fix this issue by making nilfs_grab_buffer() always set the block device
of the super block structure to the buffer head, regardless of the state
of the buffer's uptodate flag.

Classification

CVE ID: CVE-2024-53130

CVSS Base Severity: LOW

CVSS Base Score: 0.0

Affected Products

Vendor: Linux

Product: Linux

Exploit Prediction Scoring System (EPSS)

EPSS Score: 0.04% (probability of being exploited)

EPSS Percentile: 5.06% (scored less or equal to compared to others)

EPSS Date: 2025-02-03 (when was this score calculated)

References

https://git.kernel.org/stable/c/86b19031dbc79abc378dfae357f6ea33ebeb0c95
https://git.kernel.org/stable/c/b0e4765740040c44039282057ecacd7435d1d2ba
https://git.kernel.org/stable/c/ffc440a76a0f476a7e6ea838ec0dc8e9979944d1
https://git.kernel.org/stable/c/2026559a6c4ce34db117d2db8f710fe2a9420d5a

Timeline