From c263ff65d5936113cfcbb8139d34122361e2306e Mon Sep 17 00:00:00 2001 From: Roland Dreier Date: Wed, 16 Apr 2008 21:01:13 -0700 Subject: [PATCH] IB/mthca: Avoid integer overflow when allocating huge ICM table In mthca_alloc_icm_table(), the number of entries to allocate for the table->icm array is computed by calculating obj_size * nobj and then dividing by MTHCA_TABLE_CHUNK_SIZE. If nobj is really large, then obj_size * nobj may overflow and the division may get the wrong value (even a negative value). Fix this by calculating the number of objects per chunk and then dividing nobj by this value instead. This patch allows crazy configurations such as loading ib_mthca with the module parameter num_mtt=33554432 to work properly. Signed-off-by: Roland Dreier --- drivers/infiniband/hw/mthca/mthca_memfree.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/infiniband/hw/mthca/mthca_memfree.c b/drivers/infiniband/hw/mthca/mthca_memfree.c index d7d502dd741..b224079d4e1 100644 --- a/drivers/infiniband/hw/mthca/mthca_memfree.c +++ b/drivers/infiniband/hw/mthca/mthca_memfree.c @@ -359,12 +359,14 @@ struct mthca_icm_table *mthca_alloc_icm_table(struct mthca_dev *dev, int use_lowmem, int use_coherent) { struct mthca_icm_table *table; + int obj_per_chunk; int num_icm; unsigned chunk_size; int i; u8 status; - num_icm = (obj_size * nobj + MTHCA_TABLE_CHUNK_SIZE - 1) / MTHCA_TABLE_CHUNK_SIZE; + obj_per_chunk = MTHCA_TABLE_CHUNK_SIZE / obj_size; + num_icm = DIV_ROUND_UP(nobj, obj_per_chunk); table = kmalloc(sizeof *table + num_icm * sizeof *table->icm, GFP_KERNEL); if (!table) -- 2.41.1