From: Roland Dreier Date: Thu, 17 Apr 2008 04:01:13 +0000 (-0700) Subject: IB/mthca: Avoid integer overflow when allocating huge ICM table X-Git-Tag: v2.6.26-rc1~1156^2~68 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=c263ff65d5936113cfcbb8139d34122361e2306e;p=linux-2.6 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 --- diff --git a/drivers/infiniband/hw/mthca/mthca_memfree.c b/drivers/infiniband/hw/mthca/mthca_memfree.c index d7d502dd74..b224079d4e 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)