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Subject[PATCH 1/4] crypto: ccree - protect against empty or NULL scatterlists
Date
Deal gracefully with a NULL or empty scatterlist which can happen
if both cryptlen and assoclen are zero and we're doing in-place
AEAD encryption.

This fixes a crash when this causes us to try and map a NULL page,
at least with some platforms / DMA mapping configs.

Cc: stable@vger.kernel.org # v4.19+
Reported-by: Geert Uytterhoeven <geert+renesas@glider.be>
Tested-by: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Gilad Ben-Yossef <gilad@benyossef.com>
---
drivers/crypto/ccree/cc_buffer_mgr.c | 62 ++++++++++++----------------
drivers/crypto/ccree/cc_buffer_mgr.h | 1 +
2 files changed, 28 insertions(+), 35 deletions(-)

diff --git a/drivers/crypto/ccree/cc_buffer_mgr.c b/drivers/crypto/ccree/cc_buffer_mgr.c
index a72586eccd81..b938ceae7ae7 100644
--- a/drivers/crypto/ccree/cc_buffer_mgr.c
+++ b/drivers/crypto/ccree/cc_buffer_mgr.c
@@ -87,6 +87,8 @@ static unsigned int cc_get_sgl_nents(struct device *dev,
{
unsigned int nents = 0;

+ *lbytes = 0;
+
while (nbytes && sg_list) {
nents++;
/* get the number of bytes in the last entry */
@@ -95,6 +97,7 @@ static unsigned int cc_get_sgl_nents(struct device *dev,
nbytes : sg_list->length;
sg_list = sg_next(sg_list);
}
+
dev_dbg(dev, "nents %d last bytes %d\n", nents, *lbytes);
return nents;
}
@@ -290,37 +293,25 @@ static int cc_map_sg(struct device *dev, struct scatterlist *sg,
unsigned int nbytes, int direction, u32 *nents,
u32 max_sg_nents, u32 *lbytes, u32 *mapped_nents)
{
- if (sg_is_last(sg)) {
- /* One entry only case -set to DLLI */
- if (dma_map_sg(dev, sg, 1, direction) != 1) {
- dev_err(dev, "dma_map_sg() single buffer failed\n");
- return -ENOMEM;
- }
- dev_dbg(dev, "Mapped sg: dma_address=%pad page=%p addr=%pK offset=%u length=%u\n",
- &sg_dma_address(sg), sg_page(sg), sg_virt(sg),
- sg->offset, sg->length);
- *lbytes = nbytes;
- *nents = 1;
- *mapped_nents = 1;
- } else { /*sg_is_last*/
- *nents = cc_get_sgl_nents(dev, sg, nbytes, lbytes);
- if (*nents > max_sg_nents) {
- *nents = 0;
- dev_err(dev, "Too many fragments. current %d max %d\n",
- *nents, max_sg_nents);
- return -ENOMEM;
- }
- /* In case of mmu the number of mapped nents might
- * be changed from the original sgl nents
- */
- *mapped_nents = dma_map_sg(dev, sg, *nents, direction);
- if (*mapped_nents == 0) {
- *nents = 0;
- dev_err(dev, "dma_map_sg() sg buffer failed\n");
- return -ENOMEM;
- }
+ int ret = 0;
+
+ *nents = cc_get_sgl_nents(dev, sg, nbytes, lbytes);
+ if (*nents > max_sg_nents) {
+ *nents = 0;
+ dev_err(dev, "Too many fragments. current %d max %d\n",
+ *nents, max_sg_nents);
+ return -ENOMEM;
}

+ ret = dma_map_sg(dev, sg, *nents, direction);
+ if (dma_mapping_error(dev, ret)) {
+ *nents = 0;
+ dev_err(dev, "dma_map_sg() sg buffer failed %d\n", ret);
+ return -ENOMEM;
+ }
+
+ *mapped_nents = ret;
+
return 0;
}

@@ -555,11 +546,12 @@ void cc_unmap_aead_request(struct device *dev, struct aead_request *req)
sg_virt(req->src), areq_ctx->src.nents, areq_ctx->assoc.nents,
areq_ctx->assoclen, req->cryptlen);

- dma_unmap_sg(dev, req->src, sg_nents(req->src), DMA_BIDIRECTIONAL);
+ dma_unmap_sg(dev, req->src, areq_ctx->src.mapped_nents,
+ DMA_BIDIRECTIONAL);
if (req->src != req->dst) {
dev_dbg(dev, "Unmapping dst sgl: req->dst=%pK\n",
sg_virt(req->dst));
- dma_unmap_sg(dev, req->dst, sg_nents(req->dst),
+ dma_unmap_sg(dev, req->dst, areq_ctx->dst.mapped_nents,
DMA_BIDIRECTIONAL);
}
if (drvdata->coherent &&
@@ -881,7 +873,7 @@ static int cc_aead_chain_data(struct cc_drvdata *drvdata,
&src_last_bytes);
sg_index = areq_ctx->src_sgl->length;
//check where the data starts
- while (sg_index <= size_to_skip) {
+ while (src_mapped_nents && (sg_index <= size_to_skip)) {
src_mapped_nents--;
offset -= areq_ctx->src_sgl->length;
sgl = sg_next(areq_ctx->src_sgl);
@@ -908,7 +900,7 @@ static int cc_aead_chain_data(struct cc_drvdata *drvdata,
size_for_map += crypto_aead_ivsize(tfm);

rc = cc_map_sg(dev, req->dst, size_for_map, DMA_BIDIRECTIONAL,
- &areq_ctx->dst.nents,
+ &areq_ctx->dst.mapped_nents,
LLI_MAX_NUM_OF_DATA_ENTRIES, &dst_last_bytes,
&dst_mapped_nents);
if (rc)
@@ -921,7 +913,7 @@ static int cc_aead_chain_data(struct cc_drvdata *drvdata,
offset = size_to_skip;

//check where the data starts
- while (sg_index <= size_to_skip) {
+ while (dst_mapped_nents && sg_index <= size_to_skip) {
dst_mapped_nents--;
offset -= areq_ctx->dst_sgl->length;
sgl = sg_next(areq_ctx->dst_sgl);
@@ -1123,7 +1115,7 @@ int cc_map_aead_request(struct cc_drvdata *drvdata, struct aead_request *req)
if (is_gcm4543)
size_to_map += crypto_aead_ivsize(tfm);
rc = cc_map_sg(dev, req->src, size_to_map, DMA_BIDIRECTIONAL,
- &areq_ctx->src.nents,
+ &areq_ctx->src.mapped_nents,
(LLI_MAX_NUM_OF_ASSOC_DATA_ENTRIES +
LLI_MAX_NUM_OF_DATA_ENTRIES),
&dummy, &mapped_nents);
diff --git a/drivers/crypto/ccree/cc_buffer_mgr.h b/drivers/crypto/ccree/cc_buffer_mgr.h
index af434872c6ff..827b6cb1236e 100644
--- a/drivers/crypto/ccree/cc_buffer_mgr.h
+++ b/drivers/crypto/ccree/cc_buffer_mgr.h
@@ -25,6 +25,7 @@ enum cc_sg_cpy_direct {

struct cc_mlli {
cc_sram_addr_t sram_addr;
+ unsigned int mapped_nents;
unsigned int nents; //sg nents
unsigned int mlli_nents; //mlli nents might be different than the above
};
--
2.25.0
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