ring-buffer: Check resize_disabled before publishing the new subbuf order

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ring_buffer_subbuf_order_set() stores the new order and only then walks
the CPUs, returning -EBUSY if any of them has resizing disabled. A user
mapped buffer has resizing disabled, and __rb_map_vma() reads
buffer->subbuf_order without buffer->mutex, so an mmap of an already
mapped CPU racing the failing order change sizes the mapping with the
new order and inserts pages past the sub-buffer into the VMA.

Check the CPUs before storing the new order.

Cc: stable@vger.kernel.org
Fixes: 117c39200d ("ring-buffer: Introducing ring-buffer mapping functions")
Link: https://patch.msgid.link/20260912103938.1127021-1-devnexen@gmail.com
Signed-off-by: David Carlier <devnexen@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

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David Carlier 2026-09-12 11:39:38 +01:00 • committed by Steven Rostedt

parent d059d8bf2c

commit d860c67c05

1 changed files with 8 additions and 0 deletions

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kernel/trace/ring_buffer.c

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