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author | Fan Ni <fan.ni@samsung.com> | 2022-12-15 17:09:14 +0000 |
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committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2023-02-14 19:11:52 +0100 |
commit | a04c7d062b537ff787d00da95bdfe343260d4beb (patch) | |
tree | 12e0d025f9a17ea462efd0f0ffb6afc32b2f7acd | |
parent | 01815a1caf2fec67910a7fb108241b22699e6590 (diff) | |
download | linux-a04c7d062b537ff787d00da95bdfe343260d4beb.tar.gz |
cxl/region: Fix null pointer dereference for resetting decoder
commit 4fa4302d6dc7de7e8e74dc7405611a2efb4bf54b upstream. Not all decoders have a reset callback. The CXL specification allows a host bridge with a single root port to have no explicit HDM decoders. Currently the region driver assumes there are none. As such the CXL core creates a special pass through decoder instance without a commit/reset callback. Prior to this patch, the ->reset() callback was called unconditionally when calling cxl_region_decode_reset. Thus a configuration with 1 Host Bridge, 1 Root Port, and one directly attached CXL type 3 device or multiple CXL type 3 devices attached to downstream ports of a switch can cause a null pointer dereference. Before the fix, a kernel crash was observed when we destroy the region, and a pass through decoder is reset. The issue can be reproduced as below, 1) create a region with a CXL setup which includes a HB with a single root port under which a memdev is attached directly. 2) destroy the region with cxl destroy-region regionX -f. Fixes: 176baefb2eb5 ("cxl/hdm: Commit decoder state to hardware") Cc: <stable@vger.kernel.org> Signed-off-by: Fan Ni <fan.ni@samsung.com> Reviewed-by: Davidlohr Bueso <dave@stgolabs.net> Reviewed-by: Dave Jiang <dave.jiang@intel.com> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> Tested-by: Gregory Price <gregory.price@memverge.com> Reviewed-by: Gregory Price <gregory.price@memverge.com> Link: https://lore.kernel.org/r/20221215170909.2650271-1-fan.ni@samsung.com Signed-off-by: Dan Williams <dan.j.williams@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r-- | drivers/cxl/core/region.c | 8 |
1 files changed, 5 insertions, 3 deletions
diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c index c4f32c32dfd5..36962d1c2351 100644 --- a/drivers/cxl/core/region.c +++ b/drivers/cxl/core/region.c @@ -131,7 +131,7 @@ static int cxl_region_decode_reset(struct cxl_region *cxlr, int count) struct cxl_memdev *cxlmd = cxled_to_memdev(cxled); struct cxl_port *iter = cxled_to_port(cxled); struct cxl_ep *ep; - int rc; + int rc = 0; while (!is_cxl_root(to_cxl_port(iter->dev.parent))) iter = to_cxl_port(iter->dev.parent); @@ -143,7 +143,8 @@ static int cxl_region_decode_reset(struct cxl_region *cxlr, int count) cxl_rr = cxl_rr_load(iter, cxlr); cxld = cxl_rr->decoder; - rc = cxld->reset(cxld); + if (cxld->reset) + rc = cxld->reset(cxld); if (rc) return rc; } @@ -186,7 +187,8 @@ static int cxl_region_decode_commit(struct cxl_region *cxlr) iter = ep->next, ep = cxl_ep_load(iter, cxlmd)) { cxl_rr = cxl_rr_load(iter, cxlr); cxld = cxl_rr->decoder; - cxld->reset(cxld); + if (cxld->reset) + cxld->reset(cxld); } cxled->cxld.reset(&cxled->cxld); |