In the Linux kernel, the following vulnerability has been resolved:
cachefiles: remove requests from xarray during flushing requests
Even with CACHEFILES_DEAD set, we can still read the requests, so in the
following concurrency the request may be used after it has been freed:
mount | daemon_thread1 | daemon_thread2
cachefiles_ondemand_init_object
cachefiles_ondemand_send_req
REQ_A = kzalloc(sizeof(*req) + data_len)
wait_for_completion(&REQ_A->done)
cachefiles_daemon_read
cachefiles_ondemand_daemon_read
// close dev fd
cachefiles_flush_reqs
complete(&REQ_A->done)
kfree(REQ_A)
xa_lock(&cache->reqs);
cachefiles_ondemand_select_req
req->msg.opcode != CACHEFILES_OP_READ
// req use-after-free !!!
xa_unlock(&cache->reqs);
xa_destroy(&cache->reqs)
Hence remove requests from cache->reqs when flushing them to avoid
accessing freed requests.
[
{
"product": "Linux",
"vendor": "Linux",
"defaultStatus": "unaffected",
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"programFiles": [
"fs/cachefiles/daemon.c"
],
"versions": [
{
"version": "c8383054506c",
"lessThan": "9f13aacdd4ee",
"status": "affected",
"versionType": "git"
},
{
"version": "c8383054506c",
"lessThan": "50d0e55356ba",
"status": "affected",
"versionType": "git"
},
{
"version": "c8383054506c",
"lessThan": "37e19cf86a52",
"status": "affected",
"versionType": "git"
},
{
"version": "c8383054506c",
"lessThan": "0fc75c5940fa",
"status": "affected",
"versionType": "git"
}
]
},
{
"product": "Linux",
"vendor": "Linux",
"defaultStatus": "affected",
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"programFiles": [
"fs/cachefiles/daemon.c"
],
"versions": [
{
"version": "5.19",
"status": "affected"
},
{
"version": "0",
"lessThan": "5.19",
"status": "unaffected",
"versionType": "custom"
},
{
"version": "6.1.95",
"lessThanOrEqual": "6.1.*",
"status": "unaffected",
"versionType": "custom"
},
{
"version": "6.6.35",
"lessThanOrEqual": "6.6.*",
"status": "unaffected",
"versionType": "custom"
},
{
"version": "6.9.6",
"lessThanOrEqual": "6.9.*",
"status": "unaffected",
"versionType": "custom"
},
{
"version": "6.10",
"lessThanOrEqual": "*",
"status": "unaffected",
"versionType": "original_commit_for_fix"
}
]
}
]