On Thu, May 3, 2018 at 3:57 PM, Kyle Spiers <ksspiers@xxxxxxxxxx> wrote: > In the quest to remove VLAs from the kernel[1], this moves the > allocation of coefs and blocks from the stack to being kmalloc()ed. > > [1] https://lkml.org/lkml/2018/3/7/621 > > Signed-off-by: Kyle Spiers <ksspiers@xxxxxxxxxx> Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx> Thanks for working on this one! -Kees > --- > crypto/async_tx/async_pq.c | 18 ++++++++++++++---- > crypto/async_tx/raid6test.c | 8 +++++++- > 2 files changed, 21 insertions(+), 5 deletions(-) > > diff --git a/crypto/async_tx/async_pq.c b/crypto/async_tx/async_pq.c > index 56bd612927ab..af1912313a23 100644 > --- a/crypto/async_tx/async_pq.c > +++ b/crypto/async_tx/async_pq.c > @@ -194,9 +194,9 @@ async_gen_syndrome(struct page **blocks, unsigned int offset, int disks, > (src_cnt <= dma_maxpq(device, 0) || > dma_maxpq(device, DMA_PREP_CONTINUE) > 0) && > is_dma_pq_aligned(device, offset, 0, len)) { > - struct dma_async_tx_descriptor *tx; > + struct dma_async_tx_descriptor *tx = NULL; > enum dma_ctrl_flags dma_flags = 0; > - unsigned char coefs[src_cnt]; > + unsigned char *coefs; > int i, j; > > /* run the p+q asynchronously */ > @@ -207,6 +207,9 @@ async_gen_syndrome(struct page **blocks, unsigned int offset, int disks, > * sources and update the coefficients accordingly > */ > unmap->len = len; > + coefs = kmalloc_array(src_cnt, sizeof(*coefs), GFP_KERNEL); > + if (!coefs) > + goto out; > for (i = 0, j = 0; i < src_cnt; i++) { > if (blocks[i] == NULL) > continue; > @@ -240,7 +243,9 @@ async_gen_syndrome(struct page **blocks, unsigned int offset, int disks, > } > > tx = do_async_gen_syndrome(chan, coefs, j, unmap, dma_flags, submit); > +out: > dmaengine_unmap_put(unmap); > + kfree(coefs); > return tx; > } > > @@ -298,8 +303,8 @@ async_syndrome_val(struct page **blocks, unsigned int offset, int disks, > { > struct dma_chan *chan = pq_val_chan(submit, blocks, disks, len); > struct dma_device *device = chan ? chan->device : NULL; > - struct dma_async_tx_descriptor *tx; > - unsigned char coefs[disks-2]; > + struct dma_async_tx_descriptor *tx = NULL; > + unsigned char *coefs = NULL; > enum dma_ctrl_flags dma_flags = submit->cb_fn ? DMA_PREP_INTERRUPT : 0; > struct dmaengine_unmap_data *unmap = NULL; > > @@ -318,6 +323,9 @@ async_syndrome_val(struct page **blocks, unsigned int offset, int disks, > __func__, disks, len); > > unmap->len = len; > + coefs = kmalloc_array(disks - 2, sizeof(*coefs), GFP_KERNEL); > + if (!coefs) > + goto out; > for (i = 0; i < disks-2; i++) > if (likely(blocks[i])) { > unmap->addr[j] = dma_map_page(dev, blocks[i], > @@ -423,6 +431,8 @@ async_syndrome_val(struct page **blocks, unsigned int offset, int disks, > async_tx_sync_epilog(submit); > tx = NULL; > } > +out: > + kfree(coefs); > dmaengine_unmap_put(unmap); > > return tx; > diff --git a/crypto/async_tx/raid6test.c b/crypto/async_tx/raid6test.c > index dad95f45b88f..ea036b531ef2 100644 > --- a/crypto/async_tx/raid6test.c > +++ b/crypto/async_tx/raid6test.c > @@ -81,11 +81,16 @@ static void raid6_dual_recov(int disks, size_t bytes, int faila, int failb, stru > init_async_submit(&submit, 0, NULL, NULL, NULL, addr_conv); > tx = async_gen_syndrome(ptrs, 0, disks, bytes, &submit); > } else { > - struct page *blocks[disks]; > + struct page **blocks; > struct page *dest; > int count = 0; > int i; > > + blocks = kmalloc_array(disks, sizeof(*blocks), > + GFP_KERNEL); > + if (!blocks) > + return; > + > /* data+Q failure. Reconstruct data from P, > * then rebuild syndrome > */ > @@ -101,6 +106,7 @@ static void raid6_dual_recov(int disks, size_t bytes, int faila, int failb, stru > > init_async_submit(&submit, 0, tx, NULL, NULL, addr_conv); > tx = async_gen_syndrome(ptrs, 0, disks, bytes, &submit); > + kfree(blocks); > } > } else { > if (failb == disks-2) { > -- > 2.17.0.441.gb46fe60e1d-goog > -- Kees Cook Pixel Security
