Описание
In the Linux kernel, the following vulnerability has been resolved:
svcrdma: Fix pcl_for_each_segment for empty chunks
When a parsed chunk list contains a chunk whose ch_segcount is zero,
pcl_for_each_segment computes its inclusive upper bound as
&chunk->ch_segments[ch_segcount - 1]. ch_segcount is u32, so the
subtraction wraps to 0xFFFFFFFF and the bound lands far past the
ch_segments flex array. The loop body then walks unrelated memory at
sizeof(struct svc_rdma_segment) stride until it faults.
A zero-segcount chunk is reachable from the wire:
xdr_check_write_chunk() only rejects segcount values greater than
rc_maxpages, and pcl_alloc_write() links a freshly allocated chunk
onto rc_write_pcl/rc_reply_pcl before its segment-fill loop runs,
so a Write or Reply chunk advertising zero segments leaves
ch_segcount == 0 on the list. When the transport has negotiated
Send-With-Invalidate, svc_rdma_get_inv_rkey() iterates all four
PCLs with pcl_for_each_segment and dereferences segment->rs_handle
on each iteration, turning the underflow into an out-of-bounds read
and a general protection fault.
xdr_check_write_list / xdr_check_reply_chunk
pcl_alloc_write()
chunk = pcl_alloc_chunk(...) /* ch_segcount = 0 /
list_add_tail(&chunk->ch_list, &pcl->cl_chunks)
/ fill loop iterates zero times for wire segcount 0 /
svc_rdma_get_inv_rkey()
pcl_for_each_chunk(rc_write_pcl)
pcl_for_each_segment(segment, chunk)
pos <= &ch_segments[0u - 1u] / 0xFFFFFFFF /
segment->rs_handle / OOB read -> GPF */
Fix by switching the macro to a half-open upper bound that uses
ch_segcount directly. For ch_segcount == 0 the loop start equals the
loop end and the body is skipped; for ch_segcount > 0 the iteration
range is unchanged. All six existing call sites in
net/sunrpc/xprtrdma/svc_rdma_recvfrom.c and
net/sunrpc/xprtrdma/svc_rdma_rw.c remain correct under the new bound,
so no caller changes are needed.
A flaw was found in the Linux kernel's svcrdma component. A remote attacker could send a specially crafted network packet that causes an integer underflow in the pcl_for_each_segment function when processing a chunk with zero segments. This vulnerability leads to an out-of-bounds read, resulting in a general protection fault and a denial of service.
Затронутые пакеты
| Платформа | Пакет | Состояние | Рекомендация | Релиз |
|---|---|---|---|---|
| Red Hat OpenShift Container Platform 4 | openshift/ose-rhel-coreos-8 | Fix deferred | ||
| Red Hat OpenShift Container Platform 4 | openshift/ose-rhel-coreos-9 | Fix deferred |
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Дополнительная информация
Статус:
5.9 Medium
CVSS3
Связанные уязвимости
In the Linux kernel, the following vulnerability has been resolved: svcrdma: Fix pcl_for_each_segment for empty chunks When a parsed chunk list contains a chunk whose ch_segcount is zero, pcl_for_each_segment computes its inclusive upper bound as &chunk->ch_segments[ch_segcount - 1]. ch_segcount is u32, so the subtraction wraps to 0xFFFFFFFF and the bound lands far past the ch_segments flex array. The loop body then walks unrelated memory at sizeof(struct svc_rdma_segment) stride until it faults. A zero-segcount chunk is reachable from the wire: xdr_check_write_chunk() only rejects segcount values greater than rc_maxpages, and pcl_alloc_write() links a freshly allocated chunk onto rc_write_pcl/rc_reply_pcl before its segment-fill loop runs, so a Write or Reply chunk advertising zero segments leaves ch_segcount == 0 on the list. When the transport has negotiated Send-With-Invalidate, svc_rdma_get_inv_rkey() iterates all four PCLs with pcl_for_each_segment and dereferences segment->rs...
In the Linux kernel, the following vulnerability has been resolved: svcrdma: Fix pcl_for_each_segment for empty chunks When a parsed chunk list contains a chunk whose ch_segcount is zero, pcl_for_each_segment computes its inclusive upper bound as &chunk->ch_segments[ch_segcount - 1]. ch_segcount is u32, so the subtraction wraps to 0xFFFFFFFF and the bound lands far past the ch_segments flex array. The loop body then walks unrelated memory at sizeof(struct svc_rdma_segment) stride until it faults. A zero-segcount chunk is reachable from the wire: xdr_check_write_chunk() only rejects segcount values greater than rc_maxpages, and pcl_alloc_write() links a freshly allocated chunk onto rc_write_pcl/rc_reply_pcl before its segment-fill loop runs, so a Write or Reply chunk advertising zero segments leaves ch_segcount == 0 on the list. When the transport has negotiated Send-With-Invalidate, svc_rdma_get_inv_rkey() iterates all four PCLs with pcl_for_each_segment and dereferences segment->rs
In the Linux kernel, the following vulnerability has been resolved: s ...
In the Linux kernel, the following vulnerability has been resolved: svcrdma: Fix pcl_for_each_segment for empty chunks When a parsed chunk list contains a chunk whose ch_segcount is zero, pcl_for_each_segment computes its inclusive upper bound as &chunk->ch_segments[ch_segcount - 1]. ch_segcount is u32, so the subtraction wraps to 0xFFFFFFFF and the bound lands far past the ch_segments flex array. The loop body then walks unrelated memory at sizeof(struct svc_rdma_segment) stride until it faults. A zero-segcount chunk is reachable from the wire: xdr_check_write_chunk() only rejects segcount values greater than rc_maxpages, and pcl_alloc_write() links a freshly allocated chunk onto rc_write_pcl/rc_reply_pcl before its segment-fill loop runs, so a Write or Reply chunk advertising zero segments leaves ch_segcount == 0 on the list. When the transport has negotiated Send-With-Invalidate, svc_rdma_get_inv_rkey() iterates all four PCLs with pcl_for_each_segment and dereferences segment-...
5.9 Medium
CVSS3