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. Reported-by: kernel test robot <[email protected]> Reported-by: Dan Carpenter <[email protected]> Closes: https://lore.kernel.org/r/[email protected]/ Fixes: 5f3b6e839f3c ("ring-buffer: Validate boot range memory events") Signed-off-by: Daniil Dulov <[email protected]> --- kernel/trace/ring_buffer.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index 630221b00838..ad08430347b0 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -1918,6 +1918,8 @@ 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) { @@ -1928,7 +1930,6 @@ 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; /* -- 2.34.1
