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ring-buffer: Do not let subbuf be bigger than write mask

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The data on the subbuffer is measured by a write variable that also
contains status flags. The counter is just 20 bits in length. If the
subbuffer is bigger than then counter, it will fail.

Make sure that the subbuffer can not be set to greater than the counter
that keeps track of the data on the subbuffer.

Link: https://lore.kernel.org/linux-trace-kernel/20240220095112.77e9cb81@gandalf.local.home

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Fixes: 2808e31ec1 ("ring-buffer: Add interface for configuring trace sub buffer size")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
This commit is contained in:
Steven Rostedt (Google) 2024-02-20 09:51:12 -05:00
parent b401b62175
commit e78fb4eac8
1 changed files with 4 additions and 0 deletions
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4
kernel/trace/ring_buffer.c
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@ -5877,6 +5877,10 @@ int ring_buffer_subbuf_order_set(struct trace_buffer *buffer, int order)
if (psize <= BUF_PAGE_HDR_SIZE)
return -EINVAL;
/* Size of a subbuf cannot be greater than the write counter */
if (psize > RB_WRITE_MASK + 1)
return -EINVAL;
old_order = buffer->subbuf_order;
old_size = buffer->subbuf_size;