From patchwork Wed Nov 20 12:59:44 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Suraj Sonawane X-Patchwork-Id: 844644 Received: from mail-oi1-f174.google.com (mail-oi1-f174.google.com [209.85.167.174]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 32B751AA7AE; Wed, 20 Nov 2024 13:00:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.167.174 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1732107618; cv=none; b=enGll9zo7+7OwtNGaFjXmnRaN+VzZLJaA3vEq+Anx489tlb77p9IU8esKe00xzO85eoLUQqCHCoY2M55nfibhEdHas87KMhHW11rki4I2d0HLP1fxq55GN0S6cXGWVeVL9HOlY8k8ZEosli2Q8mxCSBIvxwTVOmrDE7vtUA2LcM= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1732107618; c=relaxed/simple; bh=lnSflGzBTEK00pG99f+FveddFOFgN8Bmzg0DOu60lYE=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=tKHw9ADN/LS8f2CisFfPnrAPvpuWGxl496+xOiGk82Ee61t/Lj6K3cIGImqWlHllXSiY0C/Scl485m/miGBkYsodMCGw+2/A1+IY5Lz/KY5cjGCW9zdYMdPz27qf/tTgOVMMECIa6Rk2LBVbe28fUhok3XEQRkGwNTi2hMHQWbs= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=adVLAoln; arc=none smtp.client-ip=209.85.167.174 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="adVLAoln" Received: by mail-oi1-f174.google.com with SMTP id 5614622812f47-3e5f6e44727so2450725b6e.0; Wed, 20 Nov 2024 05:00:15 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1732107615; x=1732712415; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=EDqOcDIpGKI5hYNE6Sj7mEbCMZ8HdAAjaXY3MTLtetI=; b=adVLAolnqT1jnvr6i+SPnZpkK2BxsF7O6Nmj7yuv/u9Z/eKlffQWoQr+DRWCC1pswl c//JCKg/VHtc/wVn0QMHRJb2DcyRXPGhSPfI7VT9addtW494b3q/VzuRD1hsWDj59XVq OfxdwudFtFrQnfUt/8ii5McSGSCWKfyQpZWcAHZaMg2l6cr3z0NH4oL9bZtWzGj/csNV av86TzKfcNqlOo+3NlEVSIttdANKJj5vSOKHkOeCg2DvuTT9CCFAcW5vnTyHDQo2AGCw 1ao8z7DMXRJ51cuvF+njMftkgOjX1ofOc5EzckUATlL/iBNPp6iUYMYaoHXIfeHMtU4Q pz4g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1732107615; x=1732712415; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=EDqOcDIpGKI5hYNE6Sj7mEbCMZ8HdAAjaXY3MTLtetI=; b=aX8QooZRkfEq2tHzfLzMUHaF9ns5FJk9yRuG6oxj/3EvrxpkCYyAu1zGRLV89QDhIZ Koe29JgMfurjN4U4HTEpVBSkvPRAIpnuIeAcfgJfHrDg1M5c2cmjKS2v0jleqXh54QO7 LSq8OJ9JOsePBS8lcFUN6CVpCRN5TrtnaNUR8l9ASnWJgb3VKtiYdI5bVlujtaTnBShg bBUxQz7M/01mTp11eHwHgKc0OeqclrobBHt90yuvpvHjlF+qCLgDWzJ8mFPqNifY8AgM Fa+DDnxXxyGLfoWW5w1YNdu7hJjus2+xHYCwrSFPoZXl6du5Vdg81gGPQCAb5ibuRKyj 53vQ== X-Forwarded-Encrypted: i=1; AJvYcCWB1Odvk5fGFOh/shIqfMyME+ai0Y9VA9iAyNuo4vFCVNp1alFNKOQui6qIdvculufJvjPYkktlvCCN3g==@vger.kernel.org, AJvYcCWpJ70PFHG+a5uzJA2Zeue6MxnAQV11uVP765Z9tpUfR4WxFBlE2c0RvQ4NLx3sogurQqVYymMkWXOs9rY=@vger.kernel.org X-Gm-Message-State: AOJu0YwI2YOp4OLmsDulqx1BCa7hFg0q6XvHQFh1p2Dt7R+XctEycmFe oBLXfEpTT16QxowSkEVWWI5ghTgbbhKxeFi9KUZYlctFFWVnCGnI X-Google-Smtp-Source: AGHT+IEsDvUDsMBR/Ffo23Ig5BpqckyyMpAfyq8F6YFQdtbAldYWtYa1W2QjOrCPFXyXLI/6QZR1jA== X-Received: by 2002:a05:6808:1394:b0:3e6:2889:585e with SMTP id 5614622812f47-3e7eb7d3fd6mr2383564b6e.38.1732107614916; Wed, 20 Nov 2024 05:00:14 -0800 (PST) Received: from purva-IdeaPad-Gaming-3-15IHU6.lan ([2409:40c0:11a2:6510:cf5d:dd30:9fe4:5132]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-7f8c1dae969sm9454719a12.63.2024.11.20.05.00.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 20 Nov 2024 05:00:14 -0800 (PST) From: Suraj Sonawane To: dgilbert@interlog.com Cc: James.Bottomley@HansenPartnership.com, martin.petersen@oracle.com, linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org, Suraj Sonawane , syzbot+7efb5850a17ba6ce098b@syzkaller.appspotmail.com Subject: [PATCH] scsi: sg: fix slab-use-after-free Read in sg_release Date: Wed, 20 Nov 2024 18:29:44 +0530 Message-Id: <20241120125944.88095-1-surajsonawane0215@gmail.com> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: linux-scsi@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Fix a use-after-free bug in `sg_release`, detected by syzbot with KASAN: BUG: KASAN: slab-use-after-free in lock_release+0x151/0xa30 kernel/locking/lockdep.c:5838 __mutex_unlock_slowpath+0xe2/0x750 kernel/locking/mutex.c:912 sg_release+0x1f4/0x2e0 drivers/scsi/sg.c:407 Root Cause: In `sg_release`, the function `kref_put(&sfp->f_ref, sg_remove_sfp)` is called before releasing the `open_rel_lock` mutex. The `kref_put` call may decrement the reference count of `sfp` to zero, triggering its cleanup through `sg_remove_sfp`. This cleanup includes scheduling deferred work via `sg_remove_sfp_usercontext`, which ultimately frees `sfp`. After `kref_put`, `sg_release` continues to unlock `open_rel_lock` and may reference `sfp` or `sdp`. If `sfp` has already been freed, this results in a slab-use-after-free error. Fix: The `kref_put(&sfp->f_ref, sg_remove_sfp)` call is moved after unlocking the `open_rel_lock` mutex. This ensures: - No references to `sfp` or `sdp` occur after the reference count is decremented. - Cleanup functions such as sg_remove_sfp and sg_remove_sfp_usercontext can safely execute without impacting the mutex handling in `sg_release`. The fix has been tested and validated by syzbot. This patch closes the bug reported at the following syzkaller link and ensures proper sequencing of resource cleanup and mutex operations, eliminating the risk of use-after-free errors in `sg_release`. Reported-by: syzbot+7efb5850a17ba6ce098b@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=7efb5850a17ba6ce098b Tested-by: syzbot+7efb5850a17ba6ce098b@syzkaller.appspotmail.com Fixes: cc833acbee9d ("sg: O_EXCL and other lock handling ") Signed-off-by: Suraj Sonawane --- drivers/scsi/sg.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/scsi/sg.c b/drivers/scsi/sg.c index f86be197f..457d54171 100644 --- a/drivers/scsi/sg.c +++ b/drivers/scsi/sg.c @@ -393,7 +393,6 @@ sg_release(struct inode *inode, struct file *filp) mutex_lock(&sdp->open_rel_lock); scsi_autopm_put_device(sdp->device); - kref_put(&sfp->f_ref, sg_remove_sfp); sdp->open_cnt--; /* possibly many open()s waiting on exlude clearing, start many; @@ -405,6 +404,7 @@ sg_release(struct inode *inode, struct file *filp) wake_up_interruptible(&sdp->open_wait); } mutex_unlock(&sdp->open_rel_lock); + kref_put(&sfp->f_ref, sg_remove_sfp); return 0; }