In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
ring-buffer: Use current_context for safe per-CPU buffer swap<\/p>\n
The ring_buffer_swap_cpu() function currently checks the per-CPU
\ncommitting counter to determine if a buffer is actively being written to
\nbefore performing the swap. However, there exists a race window where
\nthis check can be bypassed:<\/p>\n
ring_buffer_lock_reserve
\n cpu_buffer = buffer->buffers[cpu]; \/\/ cpu_buffer_a
\n rb_reserve_next_event
\n rb_start_commit \/\/ inc committing
\n if (unlikely(READ_ONCE(cpu_buffer->buffer) != buffer)) {…}
\n __rb_reserve_next
\n rb_move_tail
\n rb_end_commit(cpu_buffer); \/\/ dec committing => 0
\n \/* interrupt hits here, successfully swaps! *\/
\n local_inc(&cpu_buffer->committing);<\/p>\n
ring_buffer_unlock_commit
\n cpu_buffer = buffer->buffers[cpu]; \/\/ cpu_buffer_b
\n rb_commit
\n rb_end_commit
\n RB_WARN_ON(cpu_buffer, !local_read(&cpu_buffer->committing))
\n \/\/ triggers warning<\/p>\n
The committing counter can temporarily drop to 0 during a single write
\noperation (within rb_move_tail), creating a window where swap can
\nsucceed even though the write is still in progress. This leads to
\ninconsistent buffer state and triggers the RB_WARN_ON in rb_commit().<\/p>\n
Replace the committing counter check with current_context checks, which
\nare set at the entry of ring_buffer_lock_reserve() and remain valid
\nthroughout the entire write operation, providing a reliable indicator of
\nbuffer busy state during swap.<\/p>\n","protected":false},"excerpt":{"rendered":"
In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
ring-buffer: Use current_context for safe per-CPU buffer swap<\/p>\n
The ring_buffer_swap_cpu() function currently checks the per-CPU
\ncom<\/p>\n","protected":false},"template":"","meta":[],"categories":[],"tags":[],"class_list":["post-11208","vuln","type-vuln","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln\/11208","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln"}],"about":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/types\/vuln"}],"wp:attachment":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=11208"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=11208"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=11208"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}