On Fri, 13 Feb 2026 13:01:30 +0300 Daniil Dulov <[email protected]> wrote:
> 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. > Looks good to me. Acked-by: Masami Hiramatsu (Google) <[email protected]> Thanks! > 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 > > -- Masami Hiramatsu (Google) <[email protected]>
