From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9CFE5221DB9; Tue, 24 Jun 2025 04:12:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750738353; cv=none; b=Zaq5fl5UChJgMidU2qzAvEo4qURxrVO5rxTjG8Sh/vXun4llGWPlfYhfrd3rUk17/SZIHXlti72UymuwEvqLMtp9HWHIMUQkX6srEdpEvcduFLiL3mlTGK1C+93JissTR+5ky0HjWTnK1YtY8CaQSFDDaSCdf5SnASOiXEpxBq8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750738353; c=relaxed/simple; bh=facy8F0nUNf3E9Ua+SPcJBCIrt1Ln1cNIBezrr34KXI=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=o1aZneOJqZ6Z03ZIpzHaoo6+3bJCUIZMF6iWNA2tHPX/0Z7fTtKg5RpnRKaoQcMtd7oq4fUyL/yH5iGG5rU39icZI0NCHS7MY5ZuJcqODtWnMU8C4/gP0KR21dZhxfxrUGT207cQMcOPvToAIgJ1TcXO0z/CKbh2w0iHAK8iaSo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=p7nqiaGp; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="p7nqiaGp" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3DB37C4CEEF; Tue, 24 Jun 2025 04:12:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1750738353; bh=facy8F0nUNf3E9Ua+SPcJBCIrt1Ln1cNIBezrr34KXI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=p7nqiaGp0uRSIqL2Bhd4mm/rfJMyy0xZ2v1MJX4slSGaloSBNMzwj8dkABLsV9Byv wHrjWxxsZorGVSzu+ViOh9mYV2QFZ90RXvLlQMybC5M8+dQ++qee1hvnq3DCBxXYFR vYEH+gT3RyASM3QAoh4iNyUR71IG4hOefcKCB/A3se/HXUJ1le+zz6TJtd51KQby/a La9pr07tk9zX79gk0pU2zhocn5FVRl+5Wj+FBDkUg76JsPFtZDASix8L6rapdmDF3k cYGC9nLvPVbn5TqlWy6z5Eo3bt/vV1qOxHeH6R3AJ7RHnl4N0SHGv6JNJZCAIF14lg 9wB3HFaB/Fm/g== From: Sasha Levin To: patches@lists.linux.dev, stable@vger.kernel.org Cc: Johannes Berg , syzbot+92c6dd14aaa230be6855@syzkaller.appspotmail.com, Jeff Johnson , Sasha Levin , linux-wireless@vger.kernel.org Subject: [PATCH AUTOSEL 6.6 15/18] wifi: ath6kl: remove WARN on bad firmware input Date: Tue, 24 Jun 2025 00:12:11 -0400 Message-Id: <20250624041214.84135-15-sashal@kernel.org> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20250624041214.84135-1-sashal@kernel.org> References: <20250624041214.84135-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 6.6.94 Content-Transfer-Encoding: 8bit From: Johannes Berg [ Upstream commit e7417421d89358da071fd2930f91e67c7128fbff ] If the firmware gives bad input, that's nothing to do with the driver's stack at this point etc., so the WARN_ON() doesn't add any value. Additionally, this is one of the top syzbot reports now. Just print a message, and as an added bonus, print the sizes too. Reported-by: syzbot+92c6dd14aaa230be6855@syzkaller.appspotmail.com Tested-by: syzbot+92c6dd14aaa230be6855@syzkaller.appspotmail.com Acked-by: Jeff Johnson Link: https://patch.msgid.link/20250617114529.031a677a348e.I58bf1eb4ac16a82c546725ff010f3f0d2b0cca49@changeid Signed-off-by: Johannes Berg Signed-off-by: Sasha Levin --- **YES** This commit should be backported to stable kernel trees for the following reasons: ## Security and Stability Impact 1. **Syzbot Report**: The commit explicitly mentions this is "one of the top syzbot reports now", indicating it's a frequently triggered issue that impacts kernel stability testing. Syzbot is Google's continuous fuzzing infrastructure that finds kernel bugs, and high-frequency reports indicate significant impact. 2. **WARN_ON Misuse**: The removed WARN_ON is checking for bad firmware input, which violates kernel best practices. WARN_ON should only be used for "impossible" conditions that indicate kernel bugs, not for validating external input. As the commit message states: "If the firmware gives bad input, that's nothing to do with the driver's stack at this point." 3. **DoS Potential**: A WARN_ON can be triggered by malicious or corrupted firmware, potentially causing: - Stack traces in kernel logs (log spam) - Performance degradation - In some configurations, system panic (if panic_on_warn is set) ## Code Analysis The change is minimal and safe: ```c - WARN_ON(1); + ath6kl_err("mismatched byte count %d vs. expected %zd\n", + le32_to_cpu(targ_info->byte_count), + sizeof(*targ_info)); ``` The fix: - Removes the inappropriate WARN_ON - Adds informative error logging with actual vs expected sizes - Maintains the same error handling path (return -EINVAL) - No functional changes beyond logging ## Similar Precedent Looking at similar commits: - Commit #5 (ath6kl: reduce WARN to dev_dbg() in callback) - **Backported: YES** - Similar removal of WARN for known race condition - Commit #3 (ath10k: Change the warning message string) - **Backported: YES** - Modified warning to avoid syzbot confusion ## Stable Kernel Criteria This meets stable kernel criteria: - **Fixes a real bug**: Addresses inappropriate WARN_ON usage that can be triggered by external input - **Minimal change**: Only removes WARN_ON and adds error message - **Low risk**: No functional changes, just logging improvement - **Tested**: Explicitly tested by syzbot - **Clear benefit**: Reduces false positive warnings and improves debugging The commit is a straightforward fix that improves kernel robustness without introducing new risks, making it an ideal candidate for stable backporting. drivers/net/wireless/ath/ath6kl/bmi.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/net/wireless/ath/ath6kl/bmi.c b/drivers/net/wireless/ath/ath6kl/bmi.c index af98e871199d3..5a9e93fd1ef42 100644 --- a/drivers/net/wireless/ath/ath6kl/bmi.c +++ b/drivers/net/wireless/ath/ath6kl/bmi.c @@ -87,7 +87,9 @@ int ath6kl_bmi_get_target_info(struct ath6kl *ar, * We need to do some backwards compatibility to make this work. */ if (le32_to_cpu(targ_info->byte_count) != sizeof(*targ_info)) { - WARN_ON(1); + ath6kl_err("mismatched byte count %d vs. expected %zd\n", + le32_to_cpu(targ_info->byte_count), + sizeof(*targ_info)); return -EINVAL; } -- 2.39.5