In the Linux kernel, the following vulnerability has been resolved:
svcrdma: Fix offset arithmetic in read_chunk_range
svc_rdma_read_chunk_range() walks a Read chunk's segment list to
build a sub-range starting at byte offset and spanning length bytes
for a Position-Zero or Call chunk. Two arithmetic defects in the
per-segment loop produce wrong DMA lengths and a u32 underflow:
pcl_for_each_segment(segment, chunk) {
if (offset > segment->rs_length) {
offset -= segment->rs_length;
continue;
}
dummy.rs_handle = segment->rs_handle;
dummy.rs_length = min_t(u32, length,
segment->rs_length) - offset;
dummy.rs_offset = segment->rs_offset + offset;
First, the skip predicate uses '>' instead of '>='. When offset
equals the segment's full rs_length, the segment is fully consumed
and should be skipped, but the loop falls through into the body.
The resulting dummy.rs_length is min_t(u32, length, rs_length) -
rs_length, which underflows to a near-UINT_MAX u32 when length is
smaller than rs_length, or is zero otherwise.
Second, the length formula subtracts offset from the min_t() result
rather than from segment->rs_length before the cap. For offset > 0
the segment's residual is rs_length - offset, not rs_length, so the
cap must be applied to the residual. With the current bracketing,
whenever length is smaller than rs_length - offset the per-segment
length becomes length - offset instead of length, silently dropping
offset bytes from the rebuilt chunk. Combined with the boundary
case above it also enables the u32 underflow path, which propagates
a huge nr_bvec into svc_rdma_build_read_segment() and a multi-MiB
kmalloc_array_node() in svc_rdma_get_rw_ctxt().
Additionally, svc_rdma_read_call_chunk() can invoke this function
with length == 0 when the last Read chunk ends exactly at the end
of the Call chunk. With the corrected >= predicate, every segment
is skipped and the function returns the initial -EINVAL, rejecting
a valid request. Return success immediately when length is zero.
Also break out of the loop once length is fully consumed to avoid
passing zero-length segments to svc_rdma_build_read_segment().
Fix by using '>=' so a fully-consumed segment is skipped, by
moving '- offset' inside min_t() so the cap is applied to the
segment's residual length, by returning success for zero-length
requests, and by stopping iteration when the requested range has
been consumed.
svcrdma: Fix offset arithmetic in read_chunk_range
svc_rdma_read_chunk_range() walks a Read chunk's segment list to
build a sub-range starting at byte offset and spanning length bytes
for a Position-Zero or Call chunk. Two arithmetic defects in the
per-segment loop produce wrong DMA lengths and a u32 underflow:
pcl_for_each_segment(segment, chunk) {
if (offset > segment->rs_length) {
offset -= segment->rs_length;
continue;
}
dummy.rs_handle = segment->rs_handle;
dummy.rs_length = min_t(u32, length,
segment->rs_length) - offset;
dummy.rs_offset = segment->rs_offset + offset;
First, the skip predicate uses '>' instead of '>='. When offset
equals the segment's full rs_length, the segment is fully consumed
and should be skipped, but the loop falls through into the body.
The resulting dummy.rs_length is min_t(u32, length, rs_length) -
rs_length, which underflows to a near-UINT_MAX u32 when length is
smaller than rs_length, or is zero otherwise.
Second, the length formula subtracts offset from the min_t() result
rather than from segment->rs_length before the cap. For offset > 0
the segment's residual is rs_length - offset, not rs_length, so the
cap must be applied to the residual. With the current bracketing,
whenever length is smaller than rs_length - offset the per-segment
length becomes length - offset instead of length, silently dropping
offset bytes from the rebuilt chunk. Combined with the boundary
case above it also enables the u32 underflow path, which propagates
a huge nr_bvec into svc_rdma_build_read_segment() and a multi-MiB
kmalloc_array_node() in svc_rdma_get_rw_ctxt().
Additionally, svc_rdma_read_call_chunk() can invoke this function
with length == 0 when the last Read chunk ends exactly at the end
of the Call chunk. With the corrected >= predicate, every segment
is skipped and the function returns the initial -EINVAL, rejecting
a valid request. Return success immediately when length is zero.
Also break out of the loop once length is fully consumed to avoid
passing zero-length segments to svc_rdma_build_read_segment().
Fix by using '>=' so a fully-consumed segment is skipped, by
moving '- offset' inside min_t() so the cap is applied to the
segment's residual length, by returning success for zero-length
requests, and by stopping iteration when the requested range has
been consumed.
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Fixes
Solution
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Workaround
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References
History
Sat, 12 Sep 2026 00:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Weaknesses | CWE-191 | |
| References |
| |
| Metrics |
threat_severity
|
cvssV3_1
|
Fri, 11 Sep 2026 23:45:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | In the Linux kernel, the following vulnerability has been resolved: svcrdma: Fix offset arithmetic in read_chunk_range svc_rdma_read_chunk_range() walks a Read chunk's segment list to build a sub-range starting at byte offset and spanning length bytes for a Position-Zero or Call chunk. Two arithmetic defects in the per-segment loop produce wrong DMA lengths and a u32 underflow: pcl_for_each_segment(segment, chunk) { if (offset > segment->rs_length) { offset -= segment->rs_length; continue; } dummy.rs_handle = segment->rs_handle; dummy.rs_length = min_t(u32, length, segment->rs_length) - offset; dummy.rs_offset = segment->rs_offset + offset; First, the skip predicate uses '>' instead of '>='. When offset equals the segment's full rs_length, the segment is fully consumed and should be skipped, but the loop falls through into the body. The resulting dummy.rs_length is min_t(u32, length, rs_length) - rs_length, which underflows to a near-UINT_MAX u32 when length is smaller than rs_length, or is zero otherwise. Second, the length formula subtracts offset from the min_t() result rather than from segment->rs_length before the cap. For offset > 0 the segment's residual is rs_length - offset, not rs_length, so the cap must be applied to the residual. With the current bracketing, whenever length is smaller than rs_length - offset the per-segment length becomes length - offset instead of length, silently dropping offset bytes from the rebuilt chunk. Combined with the boundary case above it also enables the u32 underflow path, which propagates a huge nr_bvec into svc_rdma_build_read_segment() and a multi-MiB kmalloc_array_node() in svc_rdma_get_rw_ctxt(). Additionally, svc_rdma_read_call_chunk() can invoke this function with length == 0 when the last Read chunk ends exactly at the end of the Call chunk. With the corrected >= predicate, every segment is skipped and the function returns the initial -EINVAL, rejecting a valid request. Return success immediately when length is zero. Also break out of the loop once length is fully consumed to avoid passing zero-length segments to svc_rdma_build_read_segment(). Fix by using '>=' so a fully-consumed segment is skipped, by moving '- offset' inside min_t() so the cap is applied to the segment's residual length, by returning success for zero-length requests, and by stopping iteration when the requested range has been consumed. | |
| Title | svcrdma: Fix offset arithmetic in read_chunk_range | |
| 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: 2026-09-11T19:44:12.236Z
Reserved: 2026-09-11T19:38:34.720Z
Link: CVE-2026-89533
Vulnrichment
No data.
NVD
Status : Received
Published: 2026-09-11T20:19:36.250
Modified: 2026-09-11T20:19:36.250
Link: CVE-2026-89533
Redhat
OpenCVE Enrichment
Updated: 2026-09-13T04:15:13Z
Weaknesses