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FAILED: patch "[PATCH] libnvdimm: fix integer overflow static analysis warning" failed to apply to 4.4-stable tree

PATCH [email protected] 1 participant 1 message Sep 18, 2017

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Stable branch libnvdimm: non-volatile memory device
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The patch below does not apply to the 4.4-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

Quoted 1 line

From 58738c495e15badd2015e19ff41f1f1ed55200bc Mon Sep 17 00:00:00 2001

From: Dan Williams <[email protected]>
Date: Thu, 31 Aug 2017 15:41:55 -0700
Subject: [PATCH] libnvdimm: fix integer overflow static analysis warning

Dan reports:
The patch 62232e45f4a2: "libnvdimm: control (ioctl) messages for nvdimm_bus and nvdimm devices" from Jun 8, 2015, leads to the following static checker warning:

drivers/nvdimm/bus.c:1018 __nd_ioctl()
warn: integer overflows 'buf_len'

From a casual review, this seems like it might be a real bug. On the first iteration we load some data into in_env[]. On the second iteration we read a use controlled "in_size" from nd_cmd_in_size(). It can go up to UINT_MAX - 1. A high number means we will fill the whole in_env[] buffer. But we potentially keep looping and adding more to in_len so now it can be any value.

It simple enough to change, but it feels weird that we keep looping even though in_env is totally full. Shouldn't we just return an error if we don't have space for desc->in_num.

We keep looping because the size of the total input is allowed to be bigger than the 'envelope' which is a subset of the payload that tells us how much data to expect. For safety explicitly check that buf_len does not overflow which is what the checker flagged.

Cc <[email protected]>
Fixes 62232e45f4a2: "libnvdimm: control (ioctl) messages for nvdimm_bus..."
Reported-by Dan Carpenter <[email protected]>
Signed-off-by Dan Williams <[email protected]>
drivers/nvdimm/bus.c +9 -8
index a18c2914f4b6..66586ce23f1b 100644
@@ -911,19 +911,20 @@ static int __nd_ioctl(struct nvdimm_bus *nvdimm_bus, struct nvdimm *nvdimm,
 		int read_only, unsigned int ioctl_cmd, unsigned long arg)
 {
 	struct nvdimm_bus_descriptor *nd_desc = nvdimm_bus->nd_desc;
-	size_t buf_len = 0, in_len = 0, out_len = 0;
 	static char out_env[ND_CMD_MAX_ENVELOPE];
 	static char in_env[ND_CMD_MAX_ENVELOPE];
 	const struct nd_cmd_desc *desc = NULL;
 	unsigned int cmd = _IOC_NR(ioctl_cmd);
-	unsigned int func = cmd;
-	void __user *p = (void __user *) arg;
 	struct device *dev = &nvdimm_bus->dev;
-	struct nd_cmd_pkg pkg;
+	void __user *p = (void __user *) arg;
 	const char *cmd_name, *dimm_name;
+	u32 in_len = 0, out_len = 0;
+	unsigned int func = cmd;
 	unsigned long cmd_mask;
-	void *buf;
+	struct nd_cmd_pkg pkg;
 	int rc, i, cmd_rc;
+	u64 buf_len = 0;
+	void *buf;
 
 	if (nvdimm) {
 		desc = nd_cmd_dimm_desc(cmd);

@@ -983,7 +984,7 @@ static int __nd_ioctl(struct nvdimm_bus *nvdimm_bus, struct nvdimm *nvdimm,
 
 	if (cmd == ND_CMD_CALL) {
 		func = pkg.nd_command;
-		dev_dbg(dev, "%s:%s, idx: %llu, in: %zu, out: %zu, len %zu\n",
+		dev_dbg(dev, "%s:%s, idx: %llu, in: %u, out: %u, len %llu\n",
 				__func__, dimm_name, pkg.nd_command,
 				in_len, out_len, buf_len);
 

@@ -1013,9 +1014,9 @@ static int __nd_ioctl(struct nvdimm_bus *nvdimm_bus, struct nvdimm *nvdimm,
 		out_len += out_size;
 	}
 
-	buf_len = out_len + in_len;
+	buf_len = (u64) out_len + (u64) in_len;
 	if (buf_len > ND_IOCTL_MAX_BUFLEN) {
-		dev_dbg(dev, "%s:%s cmd: %s buf_len: %zu > %d\n", __func__,
+		dev_dbg(dev, "%s:%s cmd: %s buf_len: %llu > %d\n", __func__,
 				dimm_name, cmd_name, buf_len,
 				ND_IOCTL_MAX_BUFLEN);
 		return -EINVAL;