From 2dbe3b45879ad614968a75392cb1ef9907d8648d Mon Sep 17 00:00:00 2001 From: Dan Williams Date: Thu, 28 Apr 2022 15:10:37 -0700 Subject: [PATCH 161/217] cxl/memdev: Fix bus_invalidate() crash bus_invalidate() attempts to limit the invalidation of memdevs to a single bus scope. However, the ordering of bus_invalidate() leads to a use after free. Unconditionally invalidate memdevs (disconnect memdevs from their endpoints) and resotre on next lookup. Otherwise the following command results in the following backtrace with cxl_test: cxl disable-memdev 5,1 --force #2 0x00007ffff7fb97d4 in snprintf (__fmt=0x7ffff7fbc3ed "%s/driver", __n=98, __s=0x574d545619f7bae2 ) at /usr/include/bits/stdio2.h:71 #3 cxl_port_is_enabled (port=port@entry=0x422eb0) at ../cxl/lib/libcxl.c:1379 #4 0x00007ffff7fb99a9 in cxl_port_get_bus (port=0x422eb0) at ../cxl/lib/libcxl.c:1339 #5 0x00007ffff7fba3d0 in bus_invalidate (bus=bus@entry=0x421740) at ../cxl/lib/libcxl.c:549 #6 0x00007ffff7fba4e7 in cxl_memdev_disable_invalidate (memdev=0x416fd0) at ../cxl/lib/libcxl.c:596 #7 0x000000000040624e in memdev_action (argc=, argv=, ctx=0x4152a0, action=action@entry=0x406b70 , options=options@entry=0x40fca0 , usage=usage@entry=0x40f4b0 "cxl disable-memdev [..] []") at ../cxl/memdev.c:506 #8 0x0000000000406d57 in cmd_disable_memdev (argc=, argv=, Link: https://lore.kernel.org/r/165118383756.1676208.5717187278816036969.stgit@dwillia2-desk3.amr.corp.intel.com Signed-off-by: Dan Williams Signed-off-by: Vishal Verma --- cxl/lib/libcxl.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/cxl/lib/libcxl.c b/cxl/lib/libcxl.c index 0e8dd20..374b0f1 100644 --- a/cxl/lib/libcxl.c +++ b/cxl/lib/libcxl.c @@ -546,8 +546,7 @@ static void bus_invalidate(struct cxl_bus *bus) * indeterminate, delete them all and start over. */ cxl_memdev_foreach(ctx, memdev) - if (cxl_memdev_get_bus(memdev) == bus) - memdev->endpoint = NULL; + memdev->endpoint = NULL; bus_port = cxl_bus_get_port(bus); list_for_each_safe(&bus_port->child_ports, port, _p, list) -- 2.27.0