[PATCH 5.5 304/367] ubi: Fix an error pointer dereference in error handling code

Greg Kroah-Hartman
2020-02-10T12:55:56Z

From: Dan Carpenter <dan.carpenter@oracle.com>

commit 5d3805af279c93ef49a64701f35254676d709622 upstream.

If "seen_pebs = init_seen(ubi);" fails then "seen_pebs" is an error pointer
and we try to kfree() it which results in an Oops.

This patch re-arranges the error handling so now it only frees things
which have been allocated successfully.

Fixes: daef3dd1f0ae ("UBI: Fastmap: Add self check to detect absent PEBs")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/mtd/ubi/fastmap.c | 21 ++++++++++++---------
1 file changed, 12 insertions(+), 9 deletions(-)

--- a/drivers/mtd/ubi/fastmap.c
+++ b/drivers/mtd/ubi/fastmap.c
@@ -1137,7 +1137,7 @@ static int ubi_write_fastmap(struct ubi_
struct rb_node *tmp_rb;
int ret, i, j, free_peb_count, used_peb_count, vol_count;
int scrub_peb_count, erase_peb_count;
- unsigned long *seen_pebs = NULL;
+ unsigned long *seen_pebs;

fm_raw = ubi->fm_buf;
memset(ubi->fm_buf, 0, ubi->fm_size);
@@ -1151,7 +1151,7 @@ static int ubi_write_fastmap(struct ubi_
dvbuf = new_fm_vbuf(ubi, UBI_FM_DATA_VOLUME_ID);
if (!dvbuf) {
ret = -ENOMEM;
- goto out_kfree;
+ goto out_free_avbuf;
}

avhdr = ubi_get_vid_hdr(avbuf);
@@ -1160,7 +1160,7 @@ static int ubi_write_fastmap(struct ubi_
seen_pebs = init_seen(ubi);
if (IS_ERR(seen_pebs)) {
ret = PTR_ERR(seen_pebs);
- goto out_kfree;
+ goto out_free_dvbuf;
}

spin_lock(&ubi->volumes_lock);
@@ -1328,7 +1328,7 @@ static int ubi_write_fastmap(struct ubi_
ret = ubi_io_write_vid_hdr(ubi, new_fm->e[0]->pnum, avbuf);
if (ret) {
ubi_err(ubi, "unable to write vid_hdr to fastmap SB!");
- goto out_kfree;
+ goto out_free_seen;
}

for (i = 0; i < new_fm->used_blocks; i++) {
@@ -1350,7 +1350,7 @@ static int ubi_write_fastmap(struct ubi_
if (ret) {
ubi_err(ubi, "unable to write vid_hdr to PEB %i!",
new_fm->e[i]->pnum);
- goto out_kfree;
+ goto out_free_seen;
}
}

@@ -1360,7 +1360,7 @@ static int ubi_write_fastmap(struct ubi_
if (ret) {
ubi_err(ubi, "unable to write fastmap to PEB %i!",
new_fm->e[i]->pnum);
- goto out_kfree;
+ goto out_free_seen;
}
}

@@ -1370,10 +1370,13 @@ static int ubi_write_fastmap(struct ubi_
ret = self_check_seen(ubi, seen_pebs);
dbg_bld("fastmap written!");

-out_kfree:
- ubi_free_vid_buf(avbuf);
- ubi_free_vid_buf(dvbuf);
+out_free_seen:
free_seen(seen_pebs);
+out_free_dvbuf:
+ ubi_free_vid_buf(dvbuf);
+out_free_avbuf:
+ ubi_free_vid_buf(avbuf);
+
out:
return ret;
}