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([8.34.174.240]) by smtp.gmail.com with ESMTPSA id af79cd13be357-940f066958csm9222085a.15.2026.10.23.14.11.26 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 23 Oct 2026 14:11:26 -0700 (PDT) From: Changyul Lee To: Srinivas Kandagatla Cc: Greg Kroah-Hartman , linux-sound@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v2] slimbus: messaging: hold lock until transaction is completed Date: Fri, 23 Oct 2026 17:11:25 -0400 Message-ID: <20261023211125.2738290-1-lcy8047@gmail.com> X-Mailer: git-send-email 2.43.0 X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit slim_msg_response() releases ctrl->txn_lock right after idr_find() and then uses txn. If the request times out in the meantime, it returns, and txn is no longer valid. Keep ctrl->txn_lock held until complete() returns, so the timeout path in slim_free_txn_tid() waits until slim_msg_response() is done with txn. Call idr_remove() directly, since slim_free_txn_tid() takes the same lock. Tested on v7.3 with a delay after idr_find(), in QEMU with KASAN and on a DragonBoard 845c. Without this patch, both reproduced the use-after-free in slim_msg_response(). With this patch, neither did. Fixes: afbdcc7c384b ("slimbus: Add messaging APIs to slimbus framework") Assisted-by: LLM Signed-off-by: Changyul Lee --- Changes in v2: - Add a summary of the test results to the commit message - Remove the blank line between Fixes: and Signed-off-by: - Add Assisted-by: tag Detailed test results (QEMU and DragonBoard 845c): https://lore.kernel.org/all/CAKefsHuMzUr6LForJnx4ZQiBUMLQm60_iNEKmjxnGDTVxr88Cg@mail.gmail.com/ v1: https://lore.kernel.org/all/20260911045911.1327413-1-lcy8047@gmail.com/ drivers/slimbus/messaging.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/drivers/slimbus/messaging.c b/drivers/slimbus/messaging.c index e2dbe4a66b70..aa98f5480ba4 100644 --- a/drivers/slimbus/messaging.c +++ b/drivers/slimbus/messaging.c @@ -29,22 +29,24 @@ void slim_msg_response(struct slim_controller *ctrl, u8 *reply, u8 tid, u8 len) spin_lock_irqsave(&ctrl->txn_lock, flags); txn = idr_find(&ctrl->tid_idr, tid); - spin_unlock_irqrestore(&ctrl->txn_lock, flags); - - if (txn == NULL) + if (txn == NULL) { + spin_unlock_irqrestore(&ctrl->txn_lock, flags); return; + } msg = txn->msg; if (msg == NULL || msg->rbuf == NULL) { + spin_unlock_irqrestore(&ctrl->txn_lock, flags); dev_err(ctrl->dev, "Got response to invalid TID:%d, len:%d\n", tid, len); return; } - slim_free_txn_tid(ctrl, txn); + idr_remove(&ctrl->tid_idr, txn->tid); memcpy(msg->rbuf, reply, len); if (txn->comp) complete(txn->comp); + spin_unlock_irqrestore(&ctrl->txn_lock, flags); /* Remove runtime-pm vote now that response was received for TID txn */ pm_runtime_mark_last_busy(ctrl->dev); base-commit: c03c1a14507dfaf8b856c2608f9ac216021fc222 -- 2.43.0