scatterlist: prevent invalid free when alloc fails
When alloc fails, free_table is being called. Depending on the number of
bytes requested, we determine if we are going to call _get_free_page()
or kmalloc(). When alloc fails, our math is wrong (due to sg_size - 1),
and the last buffer is wrongfully assumed to have been allocated by
kmalloc. Hence, kfree gets called and a panic occurs.
Signed-off-by: Jeffrey Carlyle <jeff.carlyle@motorola.com>
Signed-off-by: Olusanya Soyannwo <c23746@motorola.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
diff --git a/lib/scatterlist.c b/lib/scatterlist.c
index a5ec428..4ceb05d 100644
--- a/lib/scatterlist.c
+++ b/lib/scatterlist.c
@@ -248,8 +248,18 @@
left -= sg_size;
sg = alloc_fn(alloc_size, gfp_mask);
- if (unlikely(!sg))
- return -ENOMEM;
+ if (unlikely(!sg)) {
+ /*
+ * Adjust entry count to reflect that the last
+ * entry of the previous table won't be used for
+ * linkage. Without this, sg_kfree() may get
+ * confused.
+ */
+ if (prv)
+ table->nents = ++table->orig_nents;
+
+ return -ENOMEM;
+ }
sg_init_table(sg, alloc_size);
table->nents = table->orig_nents += sg_size;
