static struct bio *clone_bio(struct bio *bio, sector_t sector,
unsigned short idx, unsigned short bv_count,
unsigned int len, struct bio_set *bs)
{
struct bio *clone;
clone = bio_alloc_bioset(GFP_NOIO, bio->bi_max_vecs, bs);
__bio_clone(clone, bio);
clone->bi_destructor = dm_bio_destructor;
clone->bi_sector = sector;
clone->bi_idx = idx;
clone->bi_vcnt = idx + bv_count;
clone->bi_size = to_bytes(len);
clone->bi_flags &= ~(1 << BIO_SEG_VALID);
return clone;
}
There is a possibility of NULL being returned from bio_alloc_bioset.
Although unlikely, it could crash the kernel.
If required, I have attached a patch (created on linux-2.6.23.9).
--Sumit
diff -uNr linux-2.6.23.9/drivers/md/dm.c linux-2.6.23.9-new/drivers/md/dm.c
--- linux-2.6.23.9/drivers/md/dm.c 2007-11-26 12:51:43.000000000 -0500
+++ linux-2.6.23.9-new/drivers/md/dm.c 2007-11-28 10:07:20.376734456 -0500
@@ -652,6 +652,13 @@
struct bio *clone;
clone = bio_alloc_bioset(GFP_NOIO, bio->bi_max_vecs, bs);
+
+ /*
+ * bio_alloc_bioset could return NULL.
+ */
+ if(!clone)
+ return clone;
+
__bio_clone(clone, bio);
clone->bi_destructor = dm_bio_destructor;
clone->bi_sector = sector;
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