From 95aea47e9ae3aa7d04e717aa6237293fa2906b19 Mon Sep 17 00:00:00 2001 From: Aleksandr Yashkin Date: Thu, 16 Jan 2020 12:23:44 +0800 Subject: [PATCH] pstore/ram: Write new dumps to start of recycled zones commit 9e5f1c19800b808a37fb9815a26d382132c26c3d upstream. The ram_core.c routines treat przs as circular buffers. When writing a new crash dump, the old buffer needs to be cleared so that the new dump doesn't end up in the wrong place (i.e. at the end). The solution to this problem is to reset the circular buffer state before writing a new Oops dump. Signed-off-by: Aleksandr Yashkin Signed-off-by: Nikolay Merinov Signed-off-by: Ariel Gilman Link: https://lore.kernel.org/r/20191223133816.28155-1-n.merinov@inango-systems.com Fixes: 896fc1f0c4c6 ("pstore/ram: Switch to persistent_ram routines") Cc: stable@vger.kernel.org Signed-off-by: Kees Cook Signed-off-by: Greg Kroah-Hartman Signed-off-by: Yang Yingliang --- fs/pstore/ram.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/fs/pstore/ram.c b/fs/pstore/ram.c index 7b399a25d1fe..b2ecfa34b2ff 100644 --- a/fs/pstore/ram.c +++ b/fs/pstore/ram.c @@ -437,6 +437,17 @@ static int notrace ramoops_pstore_write(struct pstore_record *record) prz = cxt->dprzs[cxt->dump_write_cnt]; + /* + * Since this is a new crash dump, we need to reset the buffer in + * case it still has an old dump present. Without this, the new dump + * will get appended, which would seriously confuse anything trying + * to check dump file contents. Specifically, ramoops_read_kmsg_hdr() + * expects to find a dump header in the beginning of buffer data, so + * we must to reset the buffer values, in order to ensure that the + * header will be written to the beginning of the buffer. + */ + persistent_ram_zap(prz); + /* Build header and append record contents. */ hlen = ramoops_write_kmsg_hdr(prz, record); size = record->size; -- GitLab