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From: Ben Widawsky <ben.widawsky@intel.com>
To: Dan Williams <dan.j.williams@intel.com>,
	linux-cxl@vger.kernel.org, linux-nvdimm@lists.01.org
Cc: Alison Schofield <alison.schofield@intel.com>,
	Jonathan Cameron <Jonathan.Cameron@huawei.com>,
	Ben Widawsky <ben.widawsky@intel.com>,
	Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Subject: [PATCH v2] cxl/mem: Fix potential memory leak
Date: Sat, 20 Feb 2021 19:58:46 -0800	[thread overview]
Message-ID: <20210221035846.680145-1-ben.widawsky@intel.com> (raw)
In-Reply-To: <20210220215641.604535-1-ben.widawsky@intel.com>

When submitting a command for userspace, input and output payload bounce
buffers are allocated. For a given command, both input and output
buffers may exist and so when allocation of the input buffer fails, the
output buffer must be freed too.

As far as I can tell, userspace can't easily exploit the leak to OOM a
machine unless the machine was already near OOM state.

Fixes: 583fa5e71cae ("cxl/mem: Add basic IOCTL interface")
Reported-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Ben Widawsky <ben.widawsky@intel.com>
---
 drivers/cxl/mem.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/cxl/mem.c b/drivers/cxl/mem.c
index df895bcca63a..244cb7d89678 100644
--- a/drivers/cxl/mem.c
+++ b/drivers/cxl/mem.c
@@ -514,8 +514,10 @@ static int handle_mailbox_cmd_from_user(struct cxl_mem *cxlm,
 	if (cmd->info.size_in) {
 		mbox_cmd.payload_in = vmemdup_user(u64_to_user_ptr(in_payload),
 						   cmd->info.size_in);
-		if (IS_ERR(mbox_cmd.payload_in))
+		if (IS_ERR(mbox_cmd.payload_in)) {
+			kvfree(mbox_cmd.payload_out);
 			return PTR_ERR(mbox_cmd.payload_in);
+		}
 	}
 
 	rc = cxl_mem_mbox_get(cxlm);
-- 
2.30.1
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  parent reply	other threads:[~2021-02-21  3:58 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-20 21:56 [PATCH] cxl/mem: Fixes to IOCTL interface Ben Widawsky
2021-02-21  2:38 ` Dan Williams
2021-02-21  3:47   ` Ben Widawsky
2021-02-22 16:12     ` Dan Williams
2021-02-22 17:19     ` Konrad Rzeszutek Wilk
2021-02-21  3:58 ` Ben Widawsky [this message]
2021-02-22 16:28   ` [PATCH v2] cxl/mem: Fix potential memory leak Jonathan Cameron
2021-02-22 17:09   ` Konrad Rzeszutek Wilk

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