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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>
This commit is contained in:
Jeffrey Carlyle 2010-08-30 19:55:09 +02:00 committed by Jens Axboe
parent b76b4014f9
commit edce6820a9
1 changed files with 12 additions and 2 deletions
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14
lib/scatterlist.c
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@ -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;