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cxl/port: Hold port reference until decoder release
[ Upstream commit74be98774d
] KASAN + DEBUG_KOBJECT_RELEASE reports a potential use-after-free in cxl_decoder_release() where it goes to reference its parent, a cxl_port, to free its id back to port->decoder_ida. BUG: KASAN: use-after-free in to_cxl_port+0x18/0x90 [cxl_core] Read of size 8 at addr ffff888119270908 by task kworker/35:2/379 CPU: 35 PID: 379 Comm: kworker/35:2 Tainted: G OE 5.17.0-rc2+ #198 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015 Workqueue: events kobject_delayed_cleanup Call Trace: <TASK> dump_stack_lvl+0x59/0x73 print_address_description.constprop.0+0x1f/0x150 ? to_cxl_port+0x18/0x90 [cxl_core] kasan_report.cold+0x83/0xdf ? to_cxl_port+0x18/0x90 [cxl_core] to_cxl_port+0x18/0x90 [cxl_core] cxl_decoder_release+0x2a/0x60 [cxl_core] device_release+0x5f/0x100 kobject_cleanup+0x80/0x1c0 The device core only guarantees parent lifetime until all children are unregistered. If a child needs a parent to complete its ->release() callback that child needs to hold a reference to extend the lifetime of the parent. Fixes:40ba17afdf
("cxl/acpi: Introduce cxl_decoder objects") Reported-by: Ben Widawsky <ben.widawsky@intel.com> Tested-by: Ben Widawsky <ben.widawsky@intel.com> Reviewed-by: Ben Widawsky <ben.widawsky@intel.com> Link: https://lore.kernel.org/r/164505751190.4175768.13324905271463416712.stgit@dwillia2-desk3.amr.corp.intel.com Signed-off-by: Dan Williams <dan.j.williams@intel.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
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1 changed files with 4 additions and 0 deletions
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@ -182,6 +182,7 @@ static void cxl_decoder_release(struct device *dev)
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ida_free(&port->decoder_ida, cxld->id);
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ida_free(&port->decoder_ida, cxld->id);
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kfree(cxld);
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kfree(cxld);
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put_device(&port->dev);
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}
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}
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static const struct device_type cxl_decoder_switch_type = {
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static const struct device_type cxl_decoder_switch_type = {
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@ -500,7 +501,10 @@ struct cxl_decoder *cxl_decoder_alloc(struct cxl_port *port, int nr_targets)
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if (rc < 0)
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if (rc < 0)
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goto err;
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goto err;
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/* need parent to stick around to release the id */
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get_device(&port->dev);
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cxld->id = rc;
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cxld->id = rc;
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cxld->nr_targets = nr_targets;
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cxld->nr_targets = nr_targets;
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dev = &cxld->dev;
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dev = &cxld->dev;
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device_initialize(dev);
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device_initialize(dev);
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