CVE-2025-22036

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

exfat: fix random stack corruption after get_block

When get_block is called with a buffer_head allocated on the stack, such as do_mpage_readpage, stack corruption due to buffer_head UAF may occur in the following race condition situation.

 <CPU 0>                      <CPU 1>

mpage_read_folio «bh on stack» do_mpage_readpage exfat_get_block bh_read __bh_read get_bh(bh) submit_bh wait_on_buffer … end_buffer_read_sync __end_buffer_read_notouch unlock_buffer «keep going» … … … … «bh is not valid out of mpage_read_folio» . . another_function «variable A on stack» put_bh(bh) atomic_dec(bh->b_count)

• stack corruption here *

This patch returns -EAGAIN if a folio does not have buffers when bh_read needs to be called. By doing this, the caller can fallback to functions like block_read_full_folio(), create a buffer_head in the folio, and then call get_block again.

Lets do not call bh_read() with on-stack buffer_head.

Affected Software

References

• https://git.kernel.org/stable/c/1bb7ff4204b6d4927e982cd256286c09ed4fd8ca
• https://git.kernel.org/stable/c/49b0a6ab8e528a0c1c50e37cef9b9c7c121365f2
• https://git.kernel.org/stable/c/f7447286363dc1e410bf30b87d75168f3519f9cc
• https://git.kernel.org/stable/c/f807a6bf2005740fa26b4f59c4a003dc966b9afd