CVE-2024-53130

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 buffers uptodate flag.

Weakness

A NULL pointer dereference occurs when the application dereferences a pointer that it expects to be valid, but is NULL, typically causing a crash or exit.

Affected Software

Potential Mitigations

References

• https://git.kernel.org/stable/c/0a5014ad37c77ac6a2c525137c00a0e1724f6020
• https://git.kernel.org/stable/c/0ce59fb1c73fdd5b6028226aeb46259a0cdc0957
• https://git.kernel.org/stable/c/2026559a6c4ce34db117d2db8f710fe2a9420d5a
• https://git.kernel.org/stable/c/7af3309c7a2ef26831a67125b11c34a7e01c1b2a
• https://git.kernel.org/stable/c/86b19031dbc79abc378dfae357f6ea33ebeb0c95
• https://git.kernel.org/stable/c/b0e4765740040c44039282057ecacd7435d1d2ba
• https://git.kernel.org/stable/c/d904e4d845aafbcfd8a40c1df7d999f02f062be8
• https://git.kernel.org/stable/c/ffc440a76a0f476a7e6ea838ec0dc8e9979944d1