UBI: fix use-after-free on error path (e57e0d8e) · Commits · 戴 / test

When we fail to erase a PEB, we free the corresponding erase entry object, but then re-schedule this object if the error code was something like -EAGAIN. Obviously, it is a bug to use the object after we have freed it. Reported-by:

Emese Revfy <re.emese@gmail.com> Cc: stable@kernel.org [v2.6.23+] Signed-off-by:

Artem Bityutskiy <artem.bityutskiy@linux.intel.com>

drivers/mtd/ubi/wl.c

+4 −3

Original line number	Diff line number	Diff line
		@@ -1052,7 +1052,6 @@ static int erase_worker(struct ubi_device ubi, struct ubi_work wl_wrk,

		ubi_err("failed to erase PEB %d, error %d", pnum, err);
		kfree(wl_wrk);
		kmem_cache_free(ubi_wl_entry_slab, e);

		if (err == -EINTR \|\| err == -ENOMEM \|\| err == -EAGAIN \|\|
		err == -EBUSY) {
		@@ -1065,14 +1064,16 @@ static int erase_worker(struct ubi_device ubi, struct ubi_work wl_wrk,
		goto out_ro;
		}
		return err;
		} else if (err != -EIO) {
		}

		kmem_cache_free(ubi_wl_entry_slab, e);
		if (err != -EIO)
		/*
		* If this is not %-EIO, we have no idea what to do. Scheduling
		* this physical eraseblock for erasure again would cause
		* errors again and again. Well, lets switch to R/O mode.
		*/
		goto out_ro;
		}

		/* It is %-EIO, the PEB went bad */

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