From: Daniil Dulov Date: Fri, 13 Feb 2026 10:01:30 +0000 (+0300) Subject: ring-buffer: Fix possible dereference of uninitialized pointer X-Git-Tag: v7.0-rc1~32^2~4 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f1547779402c4cd67755c33616b7203baa88420b;p=thirdparty%2Fkernel%2Flinux.git 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: kernel test robot Reported-by: Dan Carpenter Acked-by: Masami Hiramatsu (Google) Link: https://patch.msgid.link/20260213100130.2013839-1-d.dulov@aladdin.ru Closes: https://lore.kernel.org/r/202406130130.JtTGRf7W-lkp@intel.com/ Fixes: 5f3b6e839f3c ("ring-buffer: Validate boot range memory events") Signed-off-by: Daniil Dulov Signed-off-by: Steven Rostedt (Google) --- diff --git a/kernel/trace/ring_buffer.c b/kernel/trace/ring_buffer.c index d33103408955..bdc8010d8f48 100644 --- a/kernel/trace/ring_buffer.c +++ b/kernel/trace/ring_buffer.c @@ -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; /*