xprtrdma: Fix ep kref imbalance on ADDR_CHANGE
- Published
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Not listed in CISA KEV
- Fix
- Fixed in 5.8, 6.6.160, 6.12.97, 6.18.40, 7.1.5
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
- Exploitation: none
- Automatable: no
- Technical impact: total
Summary
In the Linux kernel, the following vulnerability has been resolved: xprtrdma: Fix ep kref imbalance on ADDR_CHANGE rpcrdma_cm_event_handler() falls through to the disconnected: label on RDMA_CM_EVENT_ADDR_CHANGE and calls rpcrdma_ep_put() with no matching get when the event arrives before RDMA_CM_EVENT_ESTABLISHED. The kref then underflows during connect teardown and rpcrdma_xprt_disconnect() operates on a freed ep. Reference counts across a normal connection lifecycle: rpcrdma_ep_create() kref_init ->1 rpcrdma_xprt_connect() ep_get ->2 (before post_recvs) RDMA_CM_EVENT_ESTABLISHED ep_get ->3 RDMA_CM_EVENT_DISCONNECTED ep_put ->2 rpcrdma_xprt_drain() ep_put ->1 rpcrdma_xprt_disconnect() tail ep_put ->0 (ep_destroy) The connect-time get in rpcrdma_xprt_connect(), taken just before rpcrdma_post_recvs() "while there are outstanding Receives," is balanced by rpcrdma_xprt_drain. ADDR_CHANGE before ESTABLISHED has no get to consume, so its put drops the count to 1 and the drain put then frees the ep while rpcrdma_xprt_disconnect() still holds a pointer to it. Fix by dispatching on the prior re_connect_status via xchg(): for prev == 0 (pre-ESTABLISHED) wake the connect waiter and return with no put; for prev == 1 call rpcrdma_force_disconnect() and return. The case-1 arm relies on the subsequent RDMA_CM_EVENT_DISCONNECTED event -- reliably delivered when rdma_disconnect() is called on a still-connected cm_id -- to balance the ESTABLISHED get; rpcrdma_xprt_drain() continues to balance only that connect-time get. Any other prior value means teardown is already in flight.
Timeline
- CVE published
- CISA SSVC assessment
Exploitation: none · Automatable: no · Technical impact: total
- Record last updated
Affected versions
- Linux Linux
From 2acc5cae292355f5f18ad377a2a966e7f03c8fec · fixed in a562485c359d0b20a99d466b042af9c2f7ff3326; From 2acc5cae292355f5f18ad377a2a966e7f03c8fec · fixed in cfd1bab66b042da7a778786685125656c695931b; From 2acc5cae292355f5f18ad377a2a966e7f03c8fec · fixed in d0479c2b12974aa188b10d221a5770126b118b6d; From 2acc5cae292355f5f18ad377a2a966e7f03c8fec · fixed in ffc07790539736a5d029f6a3c966b46c529f93a8; From 2acc5cae292355f5f18ad377a2a966e7f03c8fec · fixed in af9b65b29af341932625c4283dc7a23cdb62688a; From 5.7.9 · fixed in 5.8
- Linux Linux
5.8
- KernelLinux
From 5.8.0 · fixed in 6.6.160; From 6.7.0 · fixed in 6.12.97; From 6.13.0 · fixed in 6.18.40; From 6.19.0 · fixed in 7.1.5