Commit edce6820 authored by Jeffrey Carlyle's avatar Jeffrey Carlyle Committed by Jens Axboe

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: default avatarJeffrey Carlyle <[email protected]>
Signed-off-by: default avatarOlusanya Soyannwo <[email protected]>
Acked-by: default avatarTejun Heo <[email protected]>
Signed-off-by: default avatarJens Axboe <[email protected]>
parent b76b4014
......@@ -248,8 +248,18 @@ int __sg_alloc_table(struct sg_table *table, unsigned int nents,
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;
......
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