From: Quanquan Cao Date: Wed, 24 Jan 2024 09:15:26 +0000 (+0800) Subject: cxl/region：Fix overflow issue in alloc_hpa() X-Git-Tag: v6.6.17~460 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=40cb184ec84e24f1e2082e083749dbc7a0d4ca57;p=platform%2Fkernel%2Flinux-rpi.git cxl/region：Fix overflow issue in alloc_hpa() commit d76779dd3681c01a4c6c3cae4d0627c9083e0ee6 upstream. Creating a region with 16 memory devices caused a problem. The div_u64_rem function, used for dividing an unsigned 64-bit number by a 32-bit one, faced an issue when SZ_256M * p->interleave_ways. The result surpassed the maximum limit of the 32-bit divisor (4G), leading to an overflow and a remainder of 0. note: At this point, p->interleave_ways is 16, meaning 16 * 256M = 4G To fix this issue, I replaced the div_u64_rem function with div64_u64_rem and adjusted the type of the remainder. Signed-off-by: Quanquan Cao Reviewed-by: Dave Jiang Fixes: 23a22cd1c98b ("cxl/region: Allocate HPA capacity to regions") Cc: Signed-off-by: Dan Williams Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c index 472bd51..6ebd12f 100644 --- a/drivers/cxl/core/region.c +++ b/drivers/cxl/core/region.c @@ -525,7 +525,7 @@ static int alloc_hpa(struct cxl_region *cxlr, resource_size_t size) struct cxl_root_decoder *cxlrd = to_cxl_root_decoder(cxlr->dev.parent); struct cxl_region_params *p = &cxlr->params; struct resource *res; - u32 remainder = 0; + u64 remainder = 0; lockdep_assert_held_write(&cxl_region_rwsem); @@ -545,7 +545,7 @@ static int alloc_hpa(struct cxl_region *cxlr, resource_size_t size) (cxlr->mode == CXL_DECODER_PMEM && uuid_is_null(&p->uuid))) return -ENXIO; - div_u64_rem(size, SZ_256M * p->interleave_ways, &remainder); + div64_u64_rem(size, (u64)SZ_256M * p->interleave_ways, &remainder); if (remainder) return -EINVAL;