Messages in this thread Patch in this message | | | Date | Thu, 26 Aug 2010 11:04:01 -0500 | Subject | [PATCH] scatterlist: prevent invalid free when alloc fails | From | Jeffrey Carlyle <> |
| |
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.
This fix sets the end marker and allows the proper freeing of the buffers.
Signed-off-by: Olusanya Soyannwo <c23746@motorola.com> Cc: Tejun Heo <tj@kernel.org> Cc: Jens Axboe <jaxboe@fusionio.com> Signed-off-by: Jeffrey Carlyle <jeff.carlyle@motorola.com> --- lib/scatterlist.c | 11 +++++++++-- 1 files changed, 9 insertions(+), 2 deletions(-)
diff --git a/lib/scatterlist.c b/lib/scatterlist.c index a5ec428..acf2c6e 100644 --- a/lib/scatterlist.c +++ b/lib/scatterlist.c @@ -163,7 +163,7 @@ void __sg_free_table(struct sg_table *table, unsigned int max_ents, return;
sgl = table->sgl; - while (table->orig_nents) { + while (table->orig_nents && sgl) { unsigned int alloc_size = table->orig_nents; unsigned int sg_size;
@@ -227,6 +227,7 @@ int __sg_alloc_table(struct sg_table *table, unsigned int nents, { struct scatterlist *sg, *prv; unsigned int left; + unsigned int total_alloc = 0;
#ifndef ARCH_HAS_SG_CHAIN BUG_ON(nents > max_ents); @@ -248,8 +249,14 @@ int __sg_alloc_table(struct sg_table *table, unsigned int nents, left -= sg_size;
sg = alloc_fn(alloc_size, gfp_mask); - if (unlikely(!sg)) + if (unlikely(!sg)) { + table->orig_nents = total_alloc; + /* mark the end of previous entry */ + sg_mark_end(&prv[alloc_size - 1]); return -ENOMEM; + } + + total_alloc += alloc_size;
sg_init_table(sg, alloc_size); table->nents = table->orig_nents += sg_size; -- 1.6.3.3
| |