{"cve":"CVE-2026-52939","nvd":{"published":"2026-06-24T08:16:24.160","modified":"2026-07-08T19:14:19.547","status":"Analyzed","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/rds: fix NULL deref in rds_ib_send_cqe_handler() on masked atomic completion\n\nrds_ib_xmit_atomic() always programs a masked atomic opcode\n(IB_WR_MASKED_ATOMIC_CMP_AND_SWP or IB_WR_MASKED_ATOMIC_FETCH_AND_ADD)\nfor every RDS atomic cmsg.  But the completion-side switch in\nrds_ib_send_unmap_op() only handles the non-masked opcodes, so a masked\natomic completion falls through to default and returns rm == NULL while\nsend->s_op is left set.  rds_ib_send_cqe_handler() then dereferences the\nNULL rm via rm->m_final_op, oopsing in softirq context.  An unprivileged\nAF_RDS sendmsg() of an atomic cmsg over an active RDS/IB connection\ntriggers it; on hardware that natively accepts masked atomics (mlx4,\nmlx5) no extra setup is needed.\n\n  RDS/IB: rds_ib_send_unmap_op: unexpected opcode 0xd in WR!\n  Oops: general protection fault [#1] SMP KASAN\n  KASAN: null-ptr-deref in range [0x0000000000000190-0x0000000000000197]\n  RIP: rds_ib_send_cqe_handler+0x25c/0xb10 (net/rds/ib_send.c:282)\n  Call Trace:\n   <IRQ>\n   rds_ib_send_cqe_handler (net/rds/ib_send.c:282)\n   poll_scq (net/rds/ib_cm.c:274)\n   rds_ib_tasklet_fn_send (net/rds/ib_cm.c:294)\n   tasklet_action_common (kernel/softirq.c:943)\n   handle_softirqs (kernel/softirq.c:573)\n   run_ksoftirqd (kernel/softirq.c:479)\n   </IRQ>\n  Kernel panic - not syncing: Fatal exception in interrupt\n\nHandle the masked atomic opcodes in the same case as the non-masked\nones: they map to the same struct rds_message.atomic union member, so\nthe existing container_of()/rds_ib_send_unmap_atomic() body is correct\nfor them.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H","score":5.5},"cwes":["CWE-476"],"references":["https://git.kernel.org/stable/c/0f22412a2f4fbbe0251c132abee045d15a90e5b6","https://git.kernel.org/stable/c/0f7baa82a24813cdad0b06a6f8f07e4824af5ed5","https://git.kernel.org/stable/c/34080db3e70ddf94c38512ad2331e3c3afca6cc1","https://git.kernel.org/stable/c/4dd262f875e87653df50b138de1390ab0628e6b7","https://git.kernel.org/stable/c/4fd34669558085bcb589aa2078a13b0ca79e360d"],"products":["linux:linux_kernel"],"source":"nvd","synced_at":"2026-10-19T22:41:17.107060303+00:00"},"epss":{"cve":"CVE-2026-52939","score":0.00117,"percentile":0.01627,"date":"2026-11-01"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}