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Subject[PATCH 024/106] svcrdma: underflow issue in decode_write_list()
Date
3.5.7.18 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Dan Carpenter <dan.carpenter@oracle.com>

commit b2781e1021525649c0b33fffd005ef219da33926 upstream.

My static checker marks everything from ntohl() as untrusted and it
complains we could have an underflow problem doing:

return (u32 *)&ary->wc_array[nchunks];

Also on 32 bit systems the upper bound check could overflow.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
---
net/sunrpc/xprtrdma/svc_rdma_marshal.c | 20 ++++++++++++++------
1 file changed, 14 insertions(+), 6 deletions(-)

diff --git a/net/sunrpc/xprtrdma/svc_rdma_marshal.c b/net/sunrpc/xprtrdma/svc_rdma_marshal.c
index 8d2eddd..65b1462 100644
--- a/net/sunrpc/xprtrdma/svc_rdma_marshal.c
+++ b/net/sunrpc/xprtrdma/svc_rdma_marshal.c
@@ -98,6 +98,7 @@ void svc_rdma_rcl_chunk_counts(struct rpcrdma_read_chunk *ch,
*/
static u32 *decode_write_list(u32 *va, u32 *vaend)
{
+ unsigned long start, end;
int nchunks;

struct rpcrdma_write_array *ary =
@@ -113,9 +114,12 @@ static u32 *decode_write_list(u32 *va, u32 *vaend)
return NULL;
}
nchunks = ntohl(ary->wc_nchunks);
- if (((unsigned long)&ary->wc_array[0] +
- (sizeof(struct rpcrdma_write_chunk) * nchunks)) >
- (unsigned long)vaend) {
+
+ start = (unsigned long)&ary->wc_array[0];
+ end = (unsigned long)vaend;
+ if (nchunks < 0 ||
+ nchunks > (SIZE_MAX - start) / sizeof(struct rpcrdma_write_chunk) ||
+ (start + (sizeof(struct rpcrdma_write_chunk) * nchunks)) > end) {
dprintk("svcrdma: ary=%p, wc_nchunks=%d, vaend=%p\n",
ary, nchunks, vaend);
return NULL;
@@ -129,6 +133,7 @@ static u32 *decode_write_list(u32 *va, u32 *vaend)

static u32 *decode_reply_array(u32 *va, u32 *vaend)
{
+ unsigned long start, end;
int nchunks;
struct rpcrdma_write_array *ary =
(struct rpcrdma_write_array *)va;
@@ -143,9 +148,12 @@ static u32 *decode_reply_array(u32 *va, u32 *vaend)
return NULL;
}
nchunks = ntohl(ary->wc_nchunks);
- if (((unsigned long)&ary->wc_array[0] +
- (sizeof(struct rpcrdma_write_chunk) * nchunks)) >
- (unsigned long)vaend) {
+
+ start = (unsigned long)&ary->wc_array[0];
+ end = (unsigned long)vaend;
+ if (nchunks < 0 ||
+ nchunks > (SIZE_MAX - start) / sizeof(struct rpcrdma_write_chunk) ||
+ (start + (sizeof(struct rpcrdma_write_chunk) * nchunks)) > end) {
dprintk("svcrdma: ary=%p, wc_nchunks=%d, vaend=%p\n",
ary, nchunks, vaend);
return NULL;
--
1.8.3.2


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