UBI: fix use-after-free on error path
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>
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e801e128b2
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drivers/mtd/ubi
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@ -1052,7 +1052,6 @@ static int erase_worker(struct ubi_device *ubi, struct ubi_work *wl_wrk,
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ubi_err("failed to erase PEB %d, error %d", pnum, err);
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ubi_err("failed to erase PEB %d, error %d", pnum, err);
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kfree(wl_wrk);
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kfree(wl_wrk);
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kmem_cache_free(ubi_wl_entry_slab, e);
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if (err == -EINTR || err == -ENOMEM || err == -EAGAIN ||
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if (err == -EINTR || err == -ENOMEM || err == -EAGAIN ||
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err == -EBUSY) {
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err == -EBUSY) {
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@ -1065,14 +1064,16 @@ static int erase_worker(struct ubi_device *ubi, struct ubi_work *wl_wrk,
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goto out_ro;
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goto out_ro;
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}
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}
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return err;
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return err;
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} else if (err != -EIO) {
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}
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kmem_cache_free(ubi_wl_entry_slab, e);
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if (err != -EIO)
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/*
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/*
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* If this is not %-EIO, we have no idea what to do. Scheduling
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* If this is not %-EIO, we have no idea what to do. Scheduling
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* this physical eraseblock for erasure again would cause
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* this physical eraseblock for erasure again would cause
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* errors again and again. Well, lets switch to R/O mode.
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* errors again and again. Well, lets switch to R/O mode.
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*/
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*/
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goto out_ro;
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goto out_ro;
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}
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/* It is %-EIO, the PEB went bad */
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/* It is %-EIO, the PEB went bad */
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