In the Linux kernel, the following vulnerability has been resolved:
cxl/mem: Fix shutdown order
Ira reports that removing cxl_mock_mem causes a crash with the following
trace:
BUG: kernel NULL pointer dereference, address: 0000000000000044
[…]
RIP: 0010:cxl_region_decode_reset+0x7f/0x180 [cxl_core]
[…]
Call Trace:
<TASK>
cxl_region_detach+0xe8/0x210 [cxl_core]
cxl_decoder_kill_region+0x27/0x40 [cxl_core]
cxld_unregister+0x29/0x40 [cxl_core]
devres_release_all+0xb8/0x110
device_unbind_cleanup+0xe/0x70
device_release_driver_internal+0x1d2/0x210
bus_remove_device+0xd7/0x150
device_del+0x155/0x3e0
device_unregister+0x13/0x60
devm_release_action+0x4d/0x90
? __pfx_unregister_port+0x10/0x10 [cxl_core]
delete_endpoint+0x121/0x130 [cxl_core]
devres_release_all+0xb8/0x110
device_unbind_cleanup+0xe/0x70
device_release_driver_internal+0x1d2/0x210
bus_remove_device+0xd7/0x150
device_del+0x155/0x3e0
? lock_release+0x142/0x290
cdev_device_del+0x15/0x50
cxl_memdev_unregister+0x54/0x70 [cxl_core]
This crash is due to the clearing out the cxl_memdev’s driver context
(@cxlds) before the subsystem is done with it. This is ultimately due to
the region(s), that this memdev is a member, being torn down and expecting
to be able to de-reference @cxlds, like here:
static int cxl_region_decode_reset(struct cxl_region *cxlr, int count)
…
if (cxlds->rcd)
goto endpoint_reset;
…
Fix it by keeping the driver context valid until memdev-device
unregistration, and subsequently the entire stack of related
dependencies, unwinds.
[
{
"product": "Linux",
"vendor": "Linux",
"defaultStatus": "unaffected",
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"programFiles": [
"drivers/cxl/core/memdev.c"
],
"versions": [
{
"version": "9cc238c7a526",
"lessThan": "20bd0198bebd",
"status": "affected",
"versionType": "git"
},
{
"version": "9cc238c7a526",
"lessThan": "7c7371b41a14",
"status": "affected",
"versionType": "git"
},
{
"version": "9cc238c7a526",
"lessThan": "cad22a757029",
"status": "affected",
"versionType": "git"
},
{
"version": "9cc238c7a526",
"lessThan": "0ca074f7d788",
"status": "affected",
"versionType": "git"
},
{
"version": "9cc238c7a526",
"lessThan": "88d3917f82ed",
"status": "affected",
"versionType": "git"
}
]
},
{
"product": "Linux",
"vendor": "Linux",
"defaultStatus": "affected",
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"programFiles": [
"drivers/cxl/core/memdev.c"
],
"versions": [
{
"version": "5.15",
"status": "affected"
},
{
"version": "0",
"lessThan": "5.15",
"status": "unaffected",
"versionType": "custom"
},
{
"version": "5.15.139",
"lessThanOrEqual": "5.15.*",
"status": "unaffected",
"versionType": "custom"
},
{
"version": "6.1.63",
"lessThanOrEqual": "6.1.*",
"status": "unaffected",
"versionType": "custom"
},
{
"version": "6.5.12",
"lessThanOrEqual": "6.5.*",
"status": "unaffected",
"versionType": "custom"
},
{
"version": "6.6.2",
"lessThanOrEqual": "6.6.*",
"status": "unaffected",
"versionType": "custom"
},
{
"version": "6.7",
"lessThanOrEqual": "*",
"status": "unaffected",
"versionType": "original_commit_for_fix"
}
]
}
]
git.kernel.org/stable/c/0ca074f7d788627a4e0b047ca5fbdb5fc567220c
git.kernel.org/stable/c/20bd0198bebdd706bd4614b3933ef70d7c19618f
git.kernel.org/stable/c/7c7371b41a14e86f53e7dbe5baa7b1d3e0ab324b
git.kernel.org/stable/c/88d3917f82ed4215a2154432c26de1480a61b209
git.kernel.org/stable/c/cad22a757029c3a1985c221a2d4a6491ad4035ae