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UBI: Fix stale pointers in ubi->lookuptbl 

In some error paths the WL sub-system gives up on a PEB
and frees it's ubi_wl_entry struct but does not set
the entry in ubi->lookuptbl to NULL.
Fastmap can stumble over such a stale pointer as it uses
ubi->lookuptbl to find all PEBs.

Fix this by introducing a new helper function which free()s
a WL entry and removes the reference from the lookup table.

Signed-off-by: Richard Weinberger <richard@nod.at>
This commit is contained in:
Richard Weinberger 2014-11-10 16:16:23 +01:00
parent 24b7a347c3
commit ee59ba8b06
1 changed files with 31 additions and 16 deletions
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47
drivers/mtd/ubi/wl.c
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@ -215,6 +215,20 @@ static void wl_tree_add(struct ubi_wl_entry *e, struct rb_root *root)
rb_insert_color(&e->u.rb, root);
}
/**
* wl_tree_destroy - destroy a wear-leveling entry.
* @ubi: UBI device description object
* @e: the wear-leveling entry to add
*
* This function destroys a wear leveling entry and removes
* the reference from the lookup table.
*/
static void wl_entry_destroy(struct ubi_device *ubi, struct ubi_wl_entry *e)
{
ubi->lookuptbl[e->pnum] = NULL;
kmem_cache_free(ubi_wl_entry_slab, e);
}
/**
* do_work - do one pending work.
* @ubi: UBI device description object
@ -1258,7 +1272,7 @@ 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)
kmem_cache_free(ubi_wl_entry_slab, e2);
wl_entry_destroy(ubi, e2);
goto out_ro;
}
@ -1326,8 +1340,8 @@ static int wear_leveling_worker(struct ubi_device *ubi, struct ubi_work *wrk,
spin_unlock(&ubi->wl_lock);
ubi_free_vid_hdr(ubi, vid_hdr);
kmem_cache_free(ubi_wl_entry_slab, e1);
kmem_cache_free(ubi_wl_entry_slab, e2);
wl_entry_destroy(ubi, e1);
wl_entry_destroy(ubi, e2);
out_ro:
ubi_ro_mode(ubi);
@ -1469,7 +1483,7 @@ static int erase_worker(struct ubi_device *ubi, struct ubi_work *wl_wrk,
if (shutdown) {
dbg_wl("cancel erasure of PEB %d EC %d", pnum, e->ec);
kfree(wl_wrk);
kmem_cache_free(ubi_wl_entry_slab, e);
wl_entry_destroy(ubi, e);
return 0;
}
@ -1515,7 +1529,7 @@ static int erase_worker(struct ubi_device *ubi, struct ubi_work *wl_wrk,
return err;
}
kmem_cache_free(ubi_wl_entry_slab, e);
wl_entry_destroy(ubi, e);
if (err != -EIO)
/*
* If this is not %-EIO, we have no idea what to do. Scheduling
@ -1807,9 +1821,10 @@ int ubi_wl_flush(struct ubi_device *ubi, int vol_id, int lnum)
/**
* tree_destroy - destroy an RB-tree.
* @ubi: UBI device description object
* @root: the root of the tree to destroy
*/
static void tree_destroy(struct rb_root *root)
static void tree_destroy(struct ubi_device *ubi, struct rb_root *root)
{
struct rb_node *rb;
struct ubi_wl_entry *e;
@ -1831,7 +1846,7 @@ static void tree_destroy(struct rb_root *root)
rb->rb_right = NULL;
}
kmem_cache_free(ubi_wl_entry_slab, e);
wl_entry_destroy(ubi, e);
}
}
}
@ -1962,7 +1977,7 @@ int ubi_wl_init(struct ubi_device *ubi, struct ubi_attach_info *ai)
ubi_assert(!ubi_is_fm_block(ubi, e->pnum));
ubi->lookuptbl[e->pnum] = e;
if (schedule_erase(ubi, e, aeb->vol_id, aeb->lnum, 0)) {
kmem_cache_free(ubi_wl_entry_slab, e);
wl_entry_destroy(ubi, e);
goto out_free;
}
@ -2056,9 +2071,9 @@ int ubi_wl_init(struct ubi_device *ubi, struct ubi_attach_info *ai)
out_free:
shutdown_work(ubi);
tree_destroy(&ubi->used);
tree_destroy(&ubi->free);
tree_destroy(&ubi->scrub);
tree_destroy(ubi, &ubi->used);
tree_destroy(ubi, &ubi->free);
tree_destroy(ubi, &ubi->scrub);
kfree(ubi->lookuptbl);
return err;
}
@ -2075,7 +2090,7 @@ static void protection_queue_destroy(struct ubi_device *ubi)
for (i = 0; i < UBI_PROT_QUEUE_LEN; ++i) {
list_for_each_entry_safe(e, tmp, &ubi->pq[i], u.list) {
list_del(&e->u.list);
kmem_cache_free(ubi_wl_entry_slab, e);
wl_entry_destroy(ubi, e);
}
}
}
@ -2107,10 +2122,10 @@ void ubi_wl_close(struct ubi_device *ubi)
ubi_fastmap_close(ubi);
shutdown_work(ubi);
protection_queue_destroy(ubi);
tree_destroy(&ubi->used);
tree_destroy(&ubi->erroneous);
tree_destroy(&ubi->free);
tree_destroy(&ubi->scrub);
tree_destroy(ubi, &ubi->used);
tree_destroy(ubi, &ubi->erroneous);
tree_destroy(ubi, &ubi->free);
tree_destroy(ubi, &ubi->scrub);
kfree(ubi->lookuptbl);
}