From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id DC592C77B7C for ; Tue, 24 Jun 2025 04:11:56 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 3426710E4B3; Tue, 24 Jun 2025 04:11:56 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.b="MpC1Xkai"; dkim-atps=neutral Received: from nyc.source.kernel.org (nyc.source.kernel.org [147.75.193.91]) by gabe.freedesktop.org (Postfix) with ESMTPS id 62A2510E4B2; Tue, 24 Jun 2025 04:11:55 +0000 (UTC) Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by nyc.source.kernel.org (Postfix) with ESMTP id 327AAA48373; Tue, 24 Jun 2025 04:11:51 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7F8BFC4CEF0; Tue, 24 Jun 2025 04:11:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1750738310; bh=mKZohincCOjGcHzf/7QeP8sbFDNocxHn+eB/iFy60ls=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=MpC1XkaiiSWoS/+TAJXhZ7JJ6HOWmM93mxbZZiY3HGQfLW0ixml5jTwrnXJujkbyo Snhw/3vtar4Bp/HeG+xXOAMek2JJtgtWDgGVrf+HjHjUm3cWkC+zuvQjZNKsyYwDLO MFAAOcDtUkiZ63HF91TBibeXpsB8I1kMG+OepjqgnBAj+q6g/QzIGu8ryW3kVOXSZw BbSBg6jEw2xkU8qJDcYo5Xpzk/LEcde4YWAcEfTtSyqGFuWV4L1pH1pDYKSeZe0R8v WzoSBkBCBKZH1XltJsjjWbSVwlztILBjJTok93K4vvC/zhjHp/vozwd+JXAVqzIjTt B7W4VjA1AYi2A== From: Sasha Levin To: patches@lists.linux.dev, stable@vger.kernel.org Cc: Rob Clark , Rob Clark , Sasha Levin , lumag@kernel.org, linux-arm-msm@vger.kernel.org, dri-devel@lists.freedesktop.org, freedreno@lists.freedesktop.org Subject: [PATCH AUTOSEL 6.12 02/19] drm/msm: Fix another leak in the submit error path Date: Tue, 24 Jun 2025 00:11:31 -0400 Message-Id: <20250624041149.83674-2-sashal@kernel.org> X-Mailer: git-send-email 2.39.5 In-Reply-To: <20250624041149.83674-1-sashal@kernel.org> References: <20250624041149.83674-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 6.12.34 Content-Transfer-Encoding: 8bit X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" From: Rob Clark [ Upstream commit f681c2aa8676a890eacc84044717ab0fd26e058f ] put_unused_fd() doesn't free the installed file, if we've already done fd_install(). So we need to also free the sync_file. Signed-off-by: Rob Clark Patchwork: https://patchwork.freedesktop.org/patch/653583/ Signed-off-by: Rob Clark Signed-off-by: Sasha Levin --- Based on my analysis, **YES**, this commit should be backported to stable kernel trees. ## Extensive Explanation: This commit fixes a **resource leak** in the MSM DRM driver's submit error path, which is a clear bug that affects users and meets the stable tree criteria. ### The Bug: Looking at the code changes in `msm_gem_submit.c`: 1. **Before the fix**: When an error occurs after `fd_install()` has been called (line 865 in the context), the error path only calls `put_unused_fd(out_fence_fd)` at line 895-896. 2. **The problem**: As noted in the commit message, `put_unused_fd()` doesn't free the installed file if `fd_install()` has already been executed. The `sync_file` structure created by `sync_file_create()` (line 861) contains a file reference that needs to be released with `fput()`. 3. **The fix**: The patch adds proper cleanup by: - Moving `sync_file` declaration to function scope (line 661) - Adding proper cleanup in the error path (lines 895-898) that calls both `put_unused_fd()` AND `fput(sync_file->file)` when needed ### Why This Is a Good Backport Candidate: 1. **Clear Bug Fix**: This fixes a resource leak that can accumulate over time as applications hit error conditions during fence submission. 2. **Small and Contained**: The fix is minimal - just 5 lines of actual code changes that properly clean up resources. 3. **No Architectural Changes**: This doesn't introduce new features or change any APIs - it simply fixes error handling. 4. **Similar to Previous Backported Fixes**: Looking at similar commit #3 ("drm/msm: Fix submit error-path leaks") which was marked for backporting, this follows the same pattern of fixing resource leaks in error paths. 5. **Low Risk**: The change only affects error paths and adds proper cleanup that was missing. It cannot break the normal success path. 6. **Documentation Confirms**: The sync_file.c documentation (line 62-63) explicitly states that sync_files should be released with `fput(sync_file->file)`, confirming this is the correct fix. ### Pattern Analysis: Comparing with the similar commits provided: - Similar commits #1, #2, and #4 were NOT backported (they were general code improvements or non-critical changes) - Similar commits #3 and #5 WERE backported (they fixed actual resource leaks or initialization failures) This commit clearly falls into the same category as #3 and #5 - fixing an actual resource leak that can impact system stability over time. The leak occurs whenever: 1. A sync_file is successfully created 2. fd_install() succeeds 3. But then a subsequent error occurs before the submit completes Without this fix, each occurrence leaks a file descriptor and associated kernel memory, which could eventually exhaust resources in systems with heavy GPU usage that encounter errors. drivers/gpu/drm/msm/msm_gem_submit.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/msm/msm_gem_submit.c b/drivers/gpu/drm/msm/msm_gem_submit.c index 937c1f5d88cbb..4b3a8ee8e278f 100644 --- a/drivers/gpu/drm/msm/msm_gem_submit.c +++ b/drivers/gpu/drm/msm/msm_gem_submit.c @@ -667,6 +667,7 @@ int msm_ioctl_gem_submit(struct drm_device *dev, void *data, struct msm_ringbuffer *ring; struct msm_submit_post_dep *post_deps = NULL; struct drm_syncobj **syncobjs_to_reset = NULL; + struct sync_file *sync_file = NULL; int out_fence_fd = -1; unsigned i; int ret; @@ -877,7 +878,7 @@ int msm_ioctl_gem_submit(struct drm_device *dev, void *data, } if (ret == 0 && args->flags & MSM_SUBMIT_FENCE_FD_OUT) { - struct sync_file *sync_file = sync_file_create(submit->user_fence); + sync_file = sync_file_create(submit->user_fence); if (!sync_file) { ret = -ENOMEM; } else { @@ -911,8 +912,11 @@ int msm_ioctl_gem_submit(struct drm_device *dev, void *data, out_unlock: mutex_unlock(&queue->lock); out_post_unlock: - if (ret && (out_fence_fd >= 0)) + if (ret && (out_fence_fd >= 0)) { put_unused_fd(out_fence_fd); + if (sync_file) + fput(sync_file->file); + } if (!IS_ERR_OR_NULL(submit)) { msm_gem_submit_put(submit); -- 2.39.5