From: Zhihao Cheng chengzhihao1@huawei.com
maillist inclusion category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I6D1S7 CVE: NA
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit?i...
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Wear-leveling entry could be freed in error path, which may be accessed again in eraseblk_count_seq_show(), for example:
__erase_worker eraseblk_count_seq_show wl = ubi->lookuptbl[*block_number] if (wl) wl_entry_destroy ubi->lookuptbl[e->pnum] = NULL kmem_cache_free(ubi_wl_entry_slab, e) erase_count = wl->ec // UAF!
Wear-leveling entry updating/accessing in ubi->lookuptbl should be protected by ubi->wl_lock, fix it by adding ubi->wl_lock to serialize wl entry accessing between wl_entry_destroy() and eraseblk_count_seq_show().
Fetch a reproducer in [Link].
Link: https://bugzilla.kernel.org/show_bug.cgi?id=216305 Fixes: 7bccd12d27b7e3 ("ubi: Add debugfs file for tracking PEB state") Fixes: 801c135ce73d5d ("UBI: Unsorted Block Images") Signed-off-by: Zhihao Cheng chengzhihao1@huawei.com Signed-off-by: Richard Weinberger richard@nod.at Reviewed-by: Zhang Yi yi.zhang@huawei.com Signed-off-by: Jialin Zhang zhangjialin11@huawei.com --- drivers/mtd/ubi/wl.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/drivers/mtd/ubi/wl.c b/drivers/mtd/ubi/wl.c index e2e70efc02fb..6da09263e0b9 100644 --- a/drivers/mtd/ubi/wl.c +++ b/drivers/mtd/ubi/wl.c @@ -885,8 +885,11 @@ static int wear_leveling_worker(struct ubi_device *ubi, struct ubi_work *wrk,
err = do_sync_erase(ubi, e1, vol_id, lnum, 0); if (err) { - if (e2) + if (e2) { + spin_lock(&ubi->wl_lock); wl_entry_destroy(ubi, e2); + spin_unlock(&ubi->wl_lock); + } goto out_ro; }
@@ -1121,14 +1124,18 @@ static int __erase_worker(struct ubi_device *ubi, struct ubi_work *wl_wrk) /* Re-schedule the LEB for erasure */ err1 = schedule_erase(ubi, e, vol_id, lnum, 0, false); if (err1) { + spin_lock(&ubi->wl_lock); wl_entry_destroy(ubi, e); + spin_unlock(&ubi->wl_lock); err = err1; goto out_ro; } return err; }
+ spin_lock(&ubi->wl_lock); wl_entry_destroy(ubi, e); + spin_unlock(&ubi->wl_lock); if (err != -EIO) /* * If this is not %-EIO, we have no idea what to do. Scheduling