[PATCH] RDMA/irdma: Prevent overflows in memory contiguity checks

[Aleksandrova Alyona]

irdma_check_mem_contiguous() and irdma_check_mr_contiguous() verify that
PBL entries describe physically contiguous memory ranges.

Both functions calculate byte offsets using 32-bit operands. For example,
with 4 KiB pages, pg_size * pg_idx overflows 32-bit arithmetic when
pg_idx reaches 1048576. In the level-2 check, PBLE_PER_PAGE is 512, so
i * pg_size * PBLE_PER_PAGE overflows when i reaches 2048.

These values are reachable in the driver. For MRs, palloc->total_cnt
comes from iwmr->page_cnt, which is calculated by
ib_umem_num_dma_blocks(). The MR size is limited by IRDMA_MAX_MR_SIZE,
so a 4 GiB MR with 4 KiB pages can reach page_cnt of 1048576. PBLE
resources do not exclude this value either: for gen3, the limit is based
on avail_sds * MAX_PBLE_PER_SD, and MAX_PBLE_PER_SD is 0x40000, so 4 SDs
are enough for 1048576 PBLEs.

Cast one operand to u64 before the multiplications so that the offset
calculations are performed in 64-bit arithmetic.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Fixes: b48c24c2d710 ("RDMA/irdma: Implement device supported verb APIs")
Signed-off-by: Aleksandrova Alyona <aga@xxxxxxxxxx>
---
 drivers/infiniband/hw/irdma/verbs.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/infiniband/hw/irdma/verbs.c b/drivers/infiniband/hw/irdma/verbs.c
index 17086048d2d7..ab55f674cb63 100644
--- a/drivers/infiniband/hw/irdma/verbs.c
+++ b/drivers/infiniband/hw/irdma/verbs.c
@@ -2819,7 +2819,7 @@ static bool irdma_check_mem_contiguous(u64 *arr, u32 npages, u32 pg_size)
 	u32 pg_idx;
 
 	for (pg_idx = 0; pg_idx < npages; pg_idx++) {
-		if ((*arr + (pg_size * pg_idx)) != arr[pg_idx])
+		if ((*arr + ((u64)pg_size * pg_idx)) != arr[pg_idx])
 			return false;
 	}
 
@@ -2852,7 +2852,7 @@ static bool irdma_check_mr_contiguous(struct irdma_pble_alloc *palloc,
 
 	for (i = 0; i < lvl2->leaf_cnt; i++, leaf++) {
 		arr = leaf->addr;
-		if ((*start_addr + (i * pg_size * PBLE_PER_PAGE)) != *arr)
+		if ((*start_addr + ((u64)i * pg_size * PBLE_PER_PAGE)) != *arr)
 			return false;
 		ret = irdma_check_mem_contiguous(arr, leaf->cnt, pg_size);
 		if (!ret)
-- 
2.26.2