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firmware: Fix security issue with request_firmware_into_buf()

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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@vger.kernel.org # v4.8+
Signed-off-by: Vikram Mulukutla <markivx@codeaurora.org>
Signed-off-by: Rishabh Bhatnagar <rishabhb@codeaurora.org>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Rishabh Bhatnagar 2018-08-31 08:43:31 -07:00 committed by Greg Kroah-Hartman
parent 6712cc9c22
commit 422b3db2a5
1 changed files with 18 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

16
drivers/base/firmware_loader/main.c
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@ -209,11 +209,12 @@ 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);
if (!(opt_flags & FW_OPT_NOCACHE)) {
tmp = __lookup_fw_priv(fw_name);
if (tmp) {
kref_get(&tmp->ref);
@ -222,8 +223,10 @@ static int alloc_lookup_fw_priv(const char *fw_name,
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;