Critical severity · published Sep 11, 2026
CVE-2026-89533
svcrdma: Fix offset arithmetic in read_chunk_range
9.8
CVSS
0.5%
EPSS
No
On KEV
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.
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.5% · higher than 43% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
LI
Linux · Linux
d7cc73972661be4a02a1b09f1d9b3283c6c05154 before 10873311f91db9454e2fadbf9866bc819e0646d9; d7cc73972661be4a02a1b09f1d9b3283c6c05154 before addbf02dfe3b25e7e38e03bbd4e2a6ed86a14be7; d7cc73972661be4a02a1b09f1d9b3283c6c05154 before cba8543c18cf42fd80fd63effb6df6ff4f7e73ce; d7cc73972661be4a02a1b09f1d9b3283c6c05154 before 6ee4dc7476b3abc92ec1d444533a559f33f59561; d7cc73972661be4a02a1b09f1d9b3283c6c05154 before a46b35f213c2426f5d6a0458a8f7e873fc59cdfd; d7cc73972661be4a02a1b09f1d9b3283c6c05154 before 4493c96bbd0068fadf69cbae8d13426202e34cdc; +2 more · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-89533
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-89533
git.kernel.org
https://git.kernel.org/stable/c/10873311f91db9454e2fadbf9866bc819e0646d9
git.kernel.org
https://git.kernel.org/stable/c/4493c96bbd0068fadf69cbae8d13426202e34cdc
git.kernel.org
https://git.kernel.org/stable/c/4a44c140cc2f3643a39e258bb0c0ab9d0f494f5e
git.kernel.org
https://git.kernel.org/stable/c/6ee4dc7476b3abc92ec1d444533a559f33f59561
git.kernel.org
https://git.kernel.org/stable/c/a46b35f213c2426f5d6a0458a8f7e873fc59cdfd
git.kernel.org
https://git.kernel.org/stable/c/addbf02dfe3b25e7e38e03bbd4e2a6ed86a14be7
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