Commit f1547779 authored by Daniil Dulov's avatar Daniil Dulov Committed by Steven Rostedt (Google)
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ring-buffer: Fix possible dereference of uninitialized pointer 



There is a pointer head_page in rb_meta_validate_events() which is not
initialized at the beginning of a function. This pointer can be dereferenced
if there is a failure during reader page validation. In this case the control
is passed to "invalid" label where the pointer is dereferenced in a loop.

To fix the issue initialize orig_head and head_page before calling
rb_validate_buffer.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Cc: stable@vger.kernel.org
Reported-by: default avatarkernel test robot <lkp@intel.com>
Reported-by: default avatarDan Carpenter <dan.carpenter@linaro.org>
Acked-by: default avatarMasami Hiramatsu (Google) <mhiramat@kernel.org>
Link: https://patch.msgid.link/20260213100130.2013839-1-d.dulov@aladdin.ru
Closes: https://lore.kernel.org/r/202406130130.JtTGRf7W-lkp@intel.com/


Fixes: 5f3b6e83 ("ring-buffer: Validate boot range memory events")
Signed-off-by: default avatarDaniil Dulov <d.dulov@aladdin.ru>
Signed-off-by: default avatarSteven Rostedt (Google) <rostedt@goodmis.org>
parent 3c6e577d

kernel/trace/ring_buffer.c

+2 −1
Original line number Diff line number Diff line
@@ -1919,6 +1919,8 @@ static void rb_meta_validate_events(struct ring_buffer_per_cpu *cpu_buffer) 
	if (!meta || !meta->head_buffer)

		return;



	orig_head = head_page = cpu_buffer->head_page;



	/* Do the reader page first */

	ret = rb_validate_buffer(cpu_buffer->reader_page->page, cpu_buffer->cpu);

	if (ret < 0) {
@@ -1929,7 +1931,6 @@ static void rb_meta_validate_events(struct ring_buffer_per_cpu *cpu_buffer) 
	entry_bytes += local_read(&cpu_buffer->reader_page->page->commit);

	local_set(&cpu_buffer->reader_page->entries, ret);



	orig_head = head_page = cpu_buffer->head_page;

	ts = head_page->page->time_stamp;



	/*