概要

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&gt; <CPU 1&gt; mpage_read_folio <<bh on stack&gt;&gt; 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&gt;&gt; ... ... ... ... <<bh is not valid out of mpage_read_folio&gt;&gt; . . another_function <<variable A on stack&gt;&gt; put_bh(bh) atomic_dec(bh-&gt;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. Let's do not call bh_read() with on-stack buffer_head.

CVSS v3 指标

安全公告

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