Description
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.
Affected products
Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.
Linux Linux
Default version status: unaffected
78147ca8b4a9b6cf0e597ddd6bf17959e08376c2 to < 1e2e3481e39103a386b86be1c33eaef97cbdf16eaffected78147ca8b4a9b6cf0e597ddd6bf17959e08376c2 to < 3a78b841879c2a3243f74edc514236fb2907167faffected78147ca8b4a9b6cf0e597ddd6bf17959e08376c2 to < 06d0390c37fa6714624af771bd72bbf1a7ed9bb1affected78147ca8b4a9b6cf0e597ddd6bf17959e08376c2 to < 9c5a03c3dc505c0295339b0a1b9e4fe36447e482affected78147ca8b4a9b6cf0e597ddd6bf17959e08376c2 to < a1c954ca4977a4e6ec73ef92fe48073ec54f9fc8affected78147ca8b4a9b6cf0e597ddd6bf17959e08376c2 to < 6d33a7e6bf6c6b293a266a617201285a1ad32c56affected78147ca8b4a9b6cf0e597ddd6bf17959e08376c2 to < b7713a784c59515d0aba558c8f5df6a0164dd3a9affected
Linux Linux
Default version status: affected
5.11affected0 to < 5.11unaffected5.15.221 to ≤ 5.15.*unaffected6.1.188 to ≤ 6.1.*unaffected6.6.157 to ≤ 6.6.*unaffected6.12.109 to ≤ 6.12.*unaffected6.18.50 to ≤ 6.18.*unaffected7.2.4 to ≤ 7.2.*unaffected7.3 to ≤ *unaffected
References
- https://git.kernel.org/stable/c/1e2e3481e39103a386b86be1c33eaef97cbdf16e ↗
- https://git.kernel.org/stable/c/3a78b841879c2a3243f74edc514236fb2907167f ↗
- https://git.kernel.org/stable/c/06d0390c37fa6714624af771bd72bbf1a7ed9bb1 ↗
- https://git.kernel.org/stable/c/9c5a03c3dc505c0295339b0a1b9e4fe36447e482 ↗
- https://git.kernel.org/stable/c/a1c954ca4977a4e6ec73ef92fe48073ec54f9fc8 ↗
- https://git.kernel.org/stable/c/6d33a7e6bf6c6b293a266a617201285a1ad32c56 ↗
- https://git.kernel.org/stable/c/b7713a784c59515d0aba558c8f5df6a0164dd3a9 ↗