In the Linux kernel, the following vulnerability has been resolved:
io_uring/cmd: fix iovec leak when the async cmd is not recycled
An io_async_cmd carries an iovec array in ->vec.iovec, allocated when the
vec has to grow and kept across recycling through ctx->cmd_cache. On two
paths nothing frees it and io_clean_op()'s kfree(req->async_data) drops
the io_async_cmd without it.
io_req_uring_cleanup() clears the async data flags only when
io_alloc_cache_put() succeeds, and the cache holds IO_ALLOC_CACHE_MAX ==
128 entries, so once it is full the put fails and the vec is left behind.
An NVMe passthrough workload gets there without doing anything unusual:
nvme_uring_cmd_io() returns -EIOCBQUEUED, so the io_async_cmd stays
attached for the lifetime of the command and the live object count tracks
the queue depth. Above 128 the puts start failing.
->cleanup is the last chance to free an inherited vec, since
io_req_uring_cleanup() returns early for an io-wq issued command and is
not called at all for one completed without ever being issued. But
io_clean_op() calls ->cleanup only if REQ_F_NEED_CLEANUP is set, and for
uring_cmd that happens only where the vec has to grow, so a command
reusing a large enough cached vec never sets it. io_rw_alloc_async() and
io_msg_alloc_async() flag an inherited vec for exactly this reason;
io_uring_cmd_prep() does not.
Flag an inherited vec in io_uring_cmd_prep(), and free the vec when the
cache put fails, as io_req_rw_cleanup() does.
The leak is invisible under KASAN, where io_alloc_cache_vec_kasan() frees
the vec unconditionally.
io_uring/cmd: fix iovec leak when the async cmd is not recycled
An io_async_cmd carries an iovec array in ->vec.iovec, allocated when the
vec has to grow and kept across recycling through ctx->cmd_cache. On two
paths nothing frees it and io_clean_op()'s kfree(req->async_data) drops
the io_async_cmd without it.
io_req_uring_cleanup() clears the async data flags only when
io_alloc_cache_put() succeeds, and the cache holds IO_ALLOC_CACHE_MAX ==
128 entries, so once it is full the put fails and the vec is left behind.
An NVMe passthrough workload gets there without doing anything unusual:
nvme_uring_cmd_io() returns -EIOCBQUEUED, so the io_async_cmd stays
attached for the lifetime of the command and the live object count tracks
the queue depth. Above 128 the puts start failing.
->cleanup is the last chance to free an inherited vec, since
io_req_uring_cleanup() returns early for an io-wq issued command and is
not called at all for one completed without ever being issued. But
io_clean_op() calls ->cleanup only if REQ_F_NEED_CLEANUP is set, and for
uring_cmd that happens only where the vec has to grow, so a command
reusing a large enough cached vec never sets it. io_rw_alloc_async() and
io_msg_alloc_async() flag an inherited vec for exactly this reason;
io_uring_cmd_prep() does not.
Flag an inherited vec in io_uring_cmd_prep(), and free the vec when the
cache put fails, as io_req_rw_cleanup() does.
The leak is invisible under KASAN, where io_alloc_cache_vec_kasan() frees
the vec unconditionally.
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | |||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Linux | Linux | unaffected |
|
|||||||||||||||||||||
| Linux | Linux | affected |
|
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Advisories
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Fixes
Solution
No solution given by the vendor.
Workaround
No workaround given by the vendor.
References
History
Fri, 04 Sep 2026 15:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | In the Linux kernel, the following vulnerability has been resolved: io_uring/cmd: fix iovec leak when the async cmd is not recycled An io_async_cmd carries an iovec array in ->vec.iovec, allocated when the vec has to grow and kept across recycling through ctx->cmd_cache. On two paths nothing frees it and io_clean_op()'s kfree(req->async_data) drops the io_async_cmd without it. io_req_uring_cleanup() clears the async data flags only when io_alloc_cache_put() succeeds, and the cache holds IO_ALLOC_CACHE_MAX == 128 entries, so once it is full the put fails and the vec is left behind. An NVMe passthrough workload gets there without doing anything unusual: nvme_uring_cmd_io() returns -EIOCBQUEUED, so the io_async_cmd stays attached for the lifetime of the command and the live object count tracks the queue depth. Above 128 the puts start failing. ->cleanup is the last chance to free an inherited vec, since io_req_uring_cleanup() returns early for an io-wq issued command and is not called at all for one completed without ever being issued. But io_clean_op() calls ->cleanup only if REQ_F_NEED_CLEANUP is set, and for uring_cmd that happens only where the vec has to grow, so a command reusing a large enough cached vec never sets it. io_rw_alloc_async() and io_msg_alloc_async() flag an inherited vec for exactly this reason; io_uring_cmd_prep() does not. Flag an inherited vec in io_uring_cmd_prep(), and free the vec when the cache put fails, as io_req_rw_cleanup() does. The leak is invisible under KASAN, where io_alloc_cache_vec_kasan() frees the vec unconditionally. | |
| Title | io_uring/cmd: fix iovec leak when the async cmd is not recycled | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
|
Projects
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MITRE
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-09-04T15:13:31.761Z
Reserved: 2026-08-26T14:34:25.794Z
Link: CVE-2026-80811
Vulnrichment
No data.
NVD
Status : Received
Published: 2026-09-04T16:18:08.497
Modified: 2026-09-04T16:18:08.497
Link: CVE-2026-80811
Redhat
No data.
OpenCVE Enrichment
No data.
Weaknesses
No weakness.