The patch below does not apply to the 4.9-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 <stable@xxxxxxxxxxxxxxx>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>From 422b3db2a5036add39a82425b1dd9fb6c96481e8 Mon Sep 17 00:00:00 2001
From: Rishabh Bhatnagar <rishabhb@xxxxxxxxxxxxxx>
Date: Fri, 31 Aug 2018 08:43:31 -0700
Subject: [PATCH] firmware: Fix security issue with request_firmware_into_buf()
When calling request_firmware_into_buf() with the FW_OPT_NOCACHE flag
it is expected that firmware is loaded into buffer from memory.
But inside alloc_lookup_fw_priv every new firmware that is loaded is
added to the firmware cache (fwc) list head. So if any driver requests
a firmware that is already loaded the code iterates over the above
mentioned list and it can end up giving a pointer to other device driver's
firmware buffer.
Also the existing copy may either be modified by drivers, remote processors
or even freed. This causes a potential security issue with batched requests
when using request_firmware_into_buf.
Fix alloc_lookup_fw_priv to not add to the fwc head list if FW_OPT_NOCACHE
is set, and also don't do the lookup in the list.
Fixes: 0e742e9275 ("firmware: provide infrastructure to make fw caching optional")
[mcgrof: broken since feature introduction on v4.8]
Cc: stable@xxxxxxxxxxxxxxx # v4.8+
Signed-off-by: Vikram Mulukutla <markivx@xxxxxxxxxxxxxx>
Signed-off-by: Rishabh Bhatnagar <rishabhb@xxxxxxxxxxxxxx>
Signed-off-by: Luis Chamberlain <mcgrof@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
diff --git a/drivers/base/firmware_loader/main.c b/drivers/base/firmware_loader/main.c
index 0943e7065e0e..b3c0498ee433 100644
--- a/drivers/base/firmware_loader/main.c
+++ b/drivers/base/firmware_loader/main.c
@@ -209,21 +209,24 @@ static struct fw_priv *__lookup_fw_priv(const char *fw_name)
static int alloc_lookup_fw_priv(const char *fw_name,
struct firmware_cache *fwc,
struct fw_priv **fw_priv, void *dbuf,
- size_t size)
+ size_t size, enum fw_opt opt_flags)
{
struct fw_priv *tmp;
spin_lock(&fwc->lock);
- tmp = __lookup_fw_priv(fw_name);
- if (tmp) {
- kref_get(&tmp->ref);
- spin_unlock(&fwc->lock);
- *fw_priv = tmp;
- pr_debug("batched request - sharing the same struct fw_priv and lookup for multiple requests\n");
- return 1;
+ if (!(opt_flags & FW_OPT_NOCACHE)) {
+ tmp = __lookup_fw_priv(fw_name);
+ if (tmp) {
+ kref_get(&tmp->ref);
+ spin_unlock(&fwc->lock);
+ *fw_priv = tmp;
+ pr_debug("batched request - sharing the same struct fw_priv and lookup for multiple requests\n");
+ return 1;
+ }
}
+
tmp = __allocate_fw_priv(fw_name, fwc, dbuf, size);
- if (tmp)
+ if (tmp && !(opt_flags & FW_OPT_NOCACHE))
list_add(&tmp->list, &fwc->head);
spin_unlock(&fwc->lock);
@@ -493,7 +496,8 @@ int assign_fw(struct firmware *fw, struct device *device,
*/
static int
_request_firmware_prepare(struct firmware **firmware_p, const char *name,
- struct device *device, void *dbuf, size_t size)
+ struct device *device, void *dbuf, size_t size,
+ enum fw_opt opt_flags)
{
struct firmware *firmware;
struct fw_priv *fw_priv;
@@ -511,7 +515,8 @@ _request_firmware_prepare(struct firmware **firmware_p, const char *name,
return 0; /* assigned */
}
- ret = alloc_lookup_fw_priv(name, &fw_cache, &fw_priv, dbuf, size);
+ ret = alloc_lookup_fw_priv(name, &fw_cache, &fw_priv, dbuf, size,
+ opt_flags);
/*
* bind with 'priv' now to avoid warning in failure path
@@ -571,7 +576,8 @@ _request_firmware(const struct firmware **firmware_p, const char *name,
goto out;
}
- ret = _request_firmware_prepare(&fw, name, device, buf, size);
+ ret = _request_firmware_prepare(&fw, name, device, buf, size,
+ opt_flags);
if (ret <= 0) /* error or already assigned */
goto out;
