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 642FC1F63EF; Tue, 21 Jan 2025 18:12:10 +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=1737483131; cv=none; b=fUmgYR5FWpCdu6zQXaKb+5peYgkywZvkr0s4Cv/KeEdQMWB+UYuWBPfnFdlV54PkQX+BOjcggcrCtEmNkA6Qt5xxIXwXc4J9YAtUIcNOhwAhypbtC2LseHO2bOPKJF5v/+XPWQZVbPpvR1vdU/nrLrdMVQ7r3ZJu/1jonB8CECc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1737483131; c=relaxed/simple; bh=3y0u2kqf1p/hoJ0SvUmIuLf1bIVKOGQZg0MFJKuKcIo=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=iwLbFQz2LUNzZMOmKrM1w7xh0YaAbpZ8CQoZeXfL5qCz2t8sfjmiZtIXiZzAOvrIEomzhyesjvI/mYJ6l5F1T0AEFEjAWn+nRE+f/bkMGPttQVcy0MW6yGkaZlx86quy4V4nh24Nn86MnHcwz2SM5LfdafGYyqtdAJtEQVht3YY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=IJ5qwYUx; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="IJ5qwYUx" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 69F92C4CEDF; Tue, 21 Jan 2025 18:12:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1737483130; bh=3y0u2kqf1p/hoJ0SvUmIuLf1bIVKOGQZg0MFJKuKcIo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=IJ5qwYUxkE1yzFNWRBmp3W7y3y8VTICN+QZ3cGwLLZgZHgVQ4Kr6GVHOoIb3Mc20D ttl/j2ml73OSpjadC7kgzekH+sPdRa+W3L9SCQVtcQUDNJUvNEYY8xEAm0U4R1Kykr EdJP42XntkE68po03qYKeFtjOgT7o5DOsX1zpllQ= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzbot+7efb5850a17ba6ce098b@syzkaller.appspotmail.com, Suraj Sonawane , Bart Van Assche , "Martin K. Petersen" , BRUNO VERNAY , Hugo SIMELIERE Subject: [PATCH 5.15 126/127] scsi: sg: Fix slab-use-after-free read in sg_release() Date: Tue, 21 Jan 2025 18:53:18 +0100 Message-ID: <20250121174534.491726823@linuxfoundation.org> X-Mailer: git-send-email 2.48.1 In-Reply-To: <20250121174529.674452028@linuxfoundation.org> References: <20250121174529.674452028@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Suraj Sonawane commit f10593ad9bc36921f623361c9e3dd96bd52d85ee upstream. 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 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. Move the kref_put(&sfp->f_ref, sg_remove_sfp) call 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 Link: https://lore.kernel.org/r/20241120125944.88095-1-surajsonawane0215@gmail.com Reviewed-by: Bart Van Assche Signed-off-by: Martin K. Petersen Signed-off-by: BRUNO VERNAY Signed-off-by: Hugo SIMELIERE Signed-off-by: Greg Kroah-Hartman --- drivers/scsi/sg.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/drivers/scsi/sg.c +++ b/drivers/scsi/sg.c @@ -391,7 +391,6 @@ sg_release(struct inode *inode, struct f 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; @@ -403,6 +402,7 @@ sg_release(struct inode *inode, struct f wake_up_interruptible(&sdp->open_wait); } mutex_unlock(&sdp->open_rel_lock); + kref_put(&sfp->f_ref, sg_remove_sfp); return 0; }