Re: [PATCH 2/2] lightnvm: pblk: Ensure that bio is not freed on recovery

[Matias Bjørling]

On 12/07/2018 10:12 AM, Javier Gonzalez wrote:

On 6 Dec 2018, at 16.45, Igor Konopko <igor.j.kono...@intel.com> wrote:

When we are using PBLK with 0 sized metadata during recovery
process we need to reference a last page of bio. Currently
KASAN reports use-after-free in that case, since bio is
freed on IO completion.

This patch adds addtional bio reference to ensure, that we
can still use bio memory after IO completion. It also ensures
that we are not reusing the same bio on retry_rq path.

Reported-by: Hans Holmberg <hans.holmb...@cnexlabs.com>
Signed-off-by: Igor Konopko <igor.j.kono...@intel.com>
---
drivers/lightnvm/pblk-recovery.c | 12 ++++++++++--
1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/drivers/lightnvm/pblk-recovery.c b/drivers/lightnvm/pblk-recovery.c
index 009faf5db40f..3fcf062d752c 100644
--- a/drivers/lightnvm/pblk-recovery.c
+++ b/drivers/lightnvm/pblk-recovery.c
@@ -376,12 +376,14 @@ static int pblk_recov_scan_oob(struct pblk *pblk, struct 
pblk_line *line,
                rq_ppas = pblk->min_write_pgs;
        rq_len = rq_ppas * geo->csecs;

+retry_rq:
        bio = bio_map_kern(dev->q, data, rq_len, GFP_KERNEL);
        if (IS_ERR(bio))
                return PTR_ERR(bio);

        bio->bi_iter.bi_sector = 0; /* internal bio */
        bio_set_op_attrs(bio, REQ_OP_READ, 0);
+       bio_get(bio);

        rqd->bio = bio;
        rqd->opcode = NVM_OP_PREAD;
@@ -394,7 +396,6 @@ static int pblk_recov_scan_oob(struct pblk *pblk, struct 
pblk_line *line,
        if (pblk_io_aligned(pblk, rq_ppas))
                rqd->is_seq = 1;

-retry_rq:
        for (i = 0; i < rqd->nr_ppas; ) {
                struct ppa_addr ppa;
                int pos;
@@ -417,6 +418,7 @@ static int pblk_recov_scan_oob(struct pblk *pblk, struct 
pblk_line *line,
        if (ret) {
                pblk_err(pblk, "I/O submission failed: %d\n", ret);
                bio_put(bio);
+               bio_put(bio);
                return ret;
        }

@@ -428,19 +430,25 @@ static int pblk_recov_scan_oob(struct pblk *pblk, struct 
pblk_line *line,

                if (padded) {
                        pblk_log_read_err(pblk, rqd);
+                       bio_put(bio);
                        return -EINTR;
                }

                pad_distance = pblk_pad_distance(pblk, line);
                ret = pblk_recov_pad_line(pblk, line, pad_distance);
-               if (ret)
+               if (ret) {
+                       bio_put(bio);
                        return ret;
+               }

                padded = true;
+               bio_put(bio);
                goto retry_rq;
        }

        pblk_get_packed_meta(pblk, rqd);
+       bio_put(bio);
+
        for (i = 0; i < rqd->nr_ppas; i++) {
                struct pblk_sec_meta *meta = pblk_get_meta(pblk, meta_list, i);
                u64 lba = le64_to_cpu(meta->lba);
--
2.17.1

Both patches in this series look good, but since they are fixes to the
patches you sent for this window, I would suggest that you merge them
into the original set and resend. We can then test the series again and
make sure there are no regressions from V1.

Matias: would this work for you? The current series in your branch is
broken as is.

Thanks,
Javier


I've applied 1 (v2) separately since it did not merge cleanly with the 
lightnvm: pblk: add helpers for OOB metadata patch. 2 has been merged 
with the "lightnvm: pblk: support packed metadata" patch.