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authorTom Lendacky <thomas.lendacky@amd.com>2015-06-01 11:15:53 -0500
committerHerbert Xu <herbert@gondor.apana.org.au>2015-06-03 10:51:28 +0800
commitfb43f69401fef8ed2f72d7ea4a25910a0f2138bc (patch)
treed7402f0cffb4e46314c6861df7408b077a6a56cc /drivers/crypto/ccp
parentcfaed10d1f27d036b72bbdc6b1e59ea28c38ec7f (diff)
downloadlinux-fb43f69401fef8ed2f72d7ea4a25910a0f2138bc.tar.bz2
crypto: ccp - Protect against poorly marked end of sg list
Scatter gather lists can be created with more available entries than are actually used (e.g. using sg_init_table() to reserve a specific number of sg entries, but in actuality using something less than that based on the data length). The caller sometimes fails to mark the last entry with sg_mark_end(). In these cases, sg_nents() will return the original size of the sg list as opposed to the actual number of sg entries that contain valid data. On arm64, if the sg_nents() value is used in a call to dma_map_sg() in this situation, then it causes a BUG_ON in lib/swiotlb.c because an "empty" sg list entry results in dma_capable() returning false and swiotlb trying to create a bounce buffer of size 0. This occurred in the userspace crypto interface before being fixed by 0f477b655a52 ("crypto: algif - Mark sgl end at the end of data") Protect against this by using the new sg_nents_for_len() function which returns only the number of sg entries required to meet the desired length and supplying that value to dma_map_sg(). Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Diffstat (limited to 'drivers/crypto/ccp')
-rw-r--r--drivers/crypto/ccp/ccp-ops.c7
1 files changed, 5 insertions, 2 deletions
diff --git a/drivers/crypto/ccp/ccp-ops.c b/drivers/crypto/ccp/ccp-ops.c
index 542453c9ba1c..d09c6c4af4aa 100644
--- a/drivers/crypto/ccp/ccp-ops.c
+++ b/drivers/crypto/ccp/ccp-ops.c
@@ -52,7 +52,7 @@ struct ccp_dm_workarea {
struct ccp_sg_workarea {
struct scatterlist *sg;
- unsigned int nents;
+ int nents;
struct scatterlist *dma_sg;
struct device *dma_dev;
@@ -495,7 +495,10 @@ static int ccp_init_sg_workarea(struct ccp_sg_workarea *wa, struct device *dev,
if (!sg)
return 0;
- wa->nents = sg_nents(sg);
+ wa->nents = sg_nents_for_len(sg, len);
+ if (wa->nents < 0)
+ return wa->nents;
+
wa->bytes_left = len;
wa->sg_used = 0;