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Fri, 21 Aug 2026 12:49:31 -0700 (PDT) Received: from i4-l-hqh5357-03.ad.psu.edu ([130.203.139.71]) by smtp.gmail.com with ESMTPSA id d75a77b69052e-52e099baf17sm1975801cf.12.2026.08.21.12.49.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 21 Aug 2026 12:49:31 -0700 (PDT) From: Shuangpeng Bai To: Bernard Metzler , Jason Gunthorpe , Leon Romanovsky Cc: Shuangpeng Bai , linux-rdma@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: [BUG] RDMA/siw: KASAN: slab-use-after-free in siw_accept Date: Fri, 21 Aug 2026 15:46:21 -0400 Message-ID: <20260821194704.835548-1-shuangpeng.kernel@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Hi Kernel Maintainers, I hit the following report while testing current upstream kernel: KASAN: slab-use-after-free in siw_accept on commit: bd5f485f3f026225b86573e559af0b7254ef4184 (2026-08-18) To help trigger the bug more reliably, we applied a minimal diagnostic patch that only adds delays and print statements. The reproducer and .config files are here. https://gist.github.com/shuangpengbai/28addfcbf79470a62d5b4cd784e95cd2 The reproducer triggers a concurrent userspace QP transition to ERROR while siw_accept() is unwinding after a QP initialization allocation failure. The QP ERROR path drops qp->cep and frees the same struct siw_cep before siw_accept() stores cep->qp = NULL. This report is separate from the withdrawn follow-up patch: https://lore.kernel.org/linux-rdma/20260816061353.4059242-1-shuangpeng.kernel@gmail.com/ That patch concerned a concurrent QP-destruction path. This report instead involves a normal userspace ibv_modify_qp() transition to IBV_QPS_ERR on a still-live QP. We also reproduced this issue on a tree containing a93949718259 ("RDMA/siw: Fix use-after-free in siw_accept()"). That commit covers the qp->cep != cep case; this report exercises the distinct qp->cep == cep race during a concurrent userspace ibv_modify_qp(..., IBV_QPS_ERR). The QP initialization failure was induced through the built-in fail_page_alloc fault injector, restricted to the siw_qp_modify() call stack. The failing vcalloc() path is a real -ENOMEM path. The diagnostic patch shifts source line numbers in the decoded trace; in the unmodified tree, the corresponding access is `siw_cm.c:1758` and the freeing put is `siw_qp.c:663`. I'm happy to test debug patches or provide additional information. Reported-by: Shuangpeng Bai [ 409.854273] ================================================================== [ 409.856424] BUG: KASAN: slab-use-after-free in siw_accept (drivers/infiniband/sw/siw/siw_cm.c:1766) [ 409.858419] Write of size 8 at addr ffff888176620068 by task siw_accept_foll/8801 [ 409.860281] Hardware name: QEMU Ubuntu 24.04 PC v2 (i440FX + PIIX, arch_caps fix, 1996), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 [ 409.860284] Call Trace: [ 409.860288] [ 409.860291] dump_stack_lvl (lib/dump_stack.c:94 lib/dump_stack.c:120) [ 409.860298] print_report (mm/kasan/report.c:378 mm/kasan/report.c:482) [ 409.860315] kasan_report (mm/kasan/report.c:595) [ 409.860325] siw_accept (drivers/infiniband/sw/siw/siw_cm.c:1766) [ 409.860382] iw_cm_accept (drivers/infiniband/core/iwcm.c:670) [ 409.860388] rdma_accept (drivers/infiniband/core/cma.c:4643 drivers/infiniband/core/cma.c:4727) [ 409.860484] ucma_accept (drivers/infiniband/core/ucma.c:1208) [ 409.860504] ucma_write (drivers/infiniband/core/ucma.c:1856) [ 409.860528] vfs_write (fs/read_write.c:685) [ 409.860554] ksys_write (fs/read_write.c:739) [ 409.860574] do_syscall_64 (arch/x86/entry/syscall_64.c:61 arch/x86/entry/syscall_64.c:84) [ 409.860579] entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121) [ 409.860583] RIP: 0033:0x7f179cdf6fef [ 409.860588] Code: 89 54 24 18 48 89 74 24 10 89 7c 24 08 e8 29 fd ff ff 48 8b 54 24 18 48 8b 74 24 10 41 89 c0 8b 7c 24 08 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 31 44 89 c7 48 89 44 24 08 e8 5c fd ff ff 48 All code ======== 0: 89 54 24 18 mov %edx,0x18(%rsp) 4: 48 89 74 24 10 mov %rsi,0x10(%rsp) 9: 89 7c 24 08 mov %edi,0x8(%rsp) d: e8 29 fd ff ff call 0xfffffffffffffd3b 12: 48 8b 54 24 18 mov 0x18(%rsp),%rdx 17: 48 8b 74 24 10 mov 0x10(%rsp),%rsi 1c: 41 89 c0 mov %eax,%r8d 1f: 8b 7c 24 08 mov 0x8(%rsp),%edi 23: b8 01 00 00 00 mov $0x1,%eax 28: 0f 05 syscall 2a:* 48 3d 00 f0 ff ff cmp $0xfffffffffffff000,%rax <-- trapping instruction 30: 77 31 ja 0x63 32: 44 89 c7 mov %r8d,%edi 35: 48 89 44 24 08 mov %rax,0x8(%rsp) 3a: e8 5c fd ff ff call 0xfffffffffffffd9b 3f: 48 rex.W Code starting with the faulting instruction =========================================== 0: 48 3d 00 f0 ff ff cmp $0xfffffffffffff000,%rax 6: 77 31 ja 0x39 8: 44 89 c7 mov %r8d,%edi b: 48 89 44 24 08 mov %rax,0x8(%rsp) 10: e8 5c fd ff ff call 0xfffffffffffffd71 15: 48 rex.W [ 409.860592] RSP: 002b:00007ffe992e7720 EFLAGS: 00000293 ORIG_RAX: 0000000000000001 [ 409.860599] RAX: ffffffffffffffda RBX: 00007ffe992e79c0 RCX: 00007f179cdf6fef [ 409.860602] RDX: 0000000000000130 RSI: 00007ffe992e7800 RDI: 0000000000000003 [ 409.860605] RBP: 000055f0d1977070 R08: 0000000000000000 R09: 00007f179ca7e700 [ 409.860608] R10: fffffffffffffaa5 R11: 0000000000000293 R12: 0000000000000000 [ 409.860610] R13: 0000000000000000 R14: 0000000000000001 R15: 00007ffe992e7800 [ 409.860615] [ 409.897413] Allocated by task 8115 on cpu 1 at 408.747286s: [ 409.897984] kasan_save_track (mm/kasan/common.c:57 mm/kasan/common.c:78) [ 409.898409] __kasan_kmalloc (mm/kasan/common.c:398 mm/kasan/common.c:415) [ 409.898822] __kmalloc_cache_noprof (./include/linux/kasan.h:263 mm/slub.c:5489) [ 409.899305] siw_cep_alloc (./include/linux/slab.h:988 ./include/linux/slab.h:1309 drivers/infiniband/sw/siw/siw_cm.c:210) [ 409.899712] siw_cm_work_handler (drivers/infiniband/sw/siw/siw_cm.c:982 drivers/infiniband/sw/siw/siw_cm.c:1077) [ 409.900176] process_scheduled_works (kernel/workqueue.c:3322 kernel/workqueue.c:3405) [ 409.900666] worker_thread (kernel/workqueue.c:3486) [ 409.901080] kthread (kernel/kthread.c:436) [ 409.901451] ret_from_fork (archkernel/process.c:158) [ 409.901865] ret_from_fork_asm (arch/x86/entry/entry_64.S:245) [ 409.902511] Freed by task 8817 on cpu 0 at 409.051801s: [ 409.903051] kasan_save_track (mm/kasan/common.c:57 mm/kasan/common.c:78) [ 409.903477] kasan_save_free_info (mm/kasan/generic.c:584) [ 409.903930] __kasan_slab_free (mm/kasan/common.c:253 mm/kasan/common.c:285) [ 409.904366] kfree (./include/linux/kasan.h:235 mm/slub.c:2677 mm/slub.c:6377 mm/slub.c:6692) [ 409.904718] siw_qp_modify (drivers/infiniband/sw/siw/siw_qp.c:669 drivers/infiniband/sw/siw/siw_qp.c:823) [ 409.905144] siw_verbs_modify_qp (drivers/infiniband/sw/siw/siw_verbs.c:600) [ 409.905609] ib_security_modify_qp (drivers/infiniband/core/security.c:625) [ 409.906082] _ib_modify_qp (drivers/infiniband/core/verbs.c:1912) [ 409.906502] modify_qp (drivers/infiniband/core/uverbs_cmd.c:1925) [ 409.906890] ib_uverbs_modify_qp (drivers/infiniband/core/uverbs_cmd.c:1951) [ 409.907339] ib_uverbs_handler_UVERBS_METHOD_INVOKE_WRITE (drivers/infiniband/core/uverbs_std_types_device.c:44) [ 409.907989] ib_uverbs_cmd_verbs (drivers/infiniband/core/uverbs_ioctl.c:387 drivers/infiniband/core/uverbs_ioctl.c:526) [ 409.908469] ib_uverbs_ioctl (drivers/infiniband/core/uverbs_ioctl.c:555) [ 409.908898] __se_sys_ioctl (fs/ioctl.c:51 fs/ioctl.c:597 fs/ioctl.c:583) [ 409.909319] do_syscall_64 (arch/x86/entry/syscall_64.c:61 arch/x86/entry/syscall_64.c:84) [ 409.909729] entry_SYSCALL_64_after_hwframe (arch/x86/entry/entry_64.S:121) [ 409.910480] The buggy address belongs to the object at ffff888176620000 which belongs to the cache kmalloc-256 of size 256 [ 409.911716] The buggy address is located 104 bytes inside of freed 256-byte region [ffff888176620000, ffff888176620100) Best, Shuangpeng