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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@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:
parent
6712cc9c22
commit
422b3db2a5
@ -209,21 +209,24 @@ static struct fw_priv *__lookup_fw_priv(const char *fw_name)
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static int alloc_lookup_fw_priv(const char *fw_name,
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struct firmware_cache *fwc,
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struct fw_priv **fw_priv, void *dbuf,
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size_t size)
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size_t size, enum fw_opt opt_flags)
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{
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struct fw_priv *tmp;
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spin_lock(&fwc->lock);
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tmp = __lookup_fw_priv(fw_name);
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if (tmp) {
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kref_get(&tmp->ref);
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spin_unlock(&fwc->lock);
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*fw_priv = tmp;
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pr_debug("batched request - sharing the same struct fw_priv and lookup for multiple requests\n");
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return 1;
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if (!(opt_flags & FW_OPT_NOCACHE)) {
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tmp = __lookup_fw_priv(fw_name);
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if (tmp) {
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kref_get(&tmp->ref);
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spin_unlock(&fwc->lock);
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*fw_priv = tmp;
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pr_debug("batched request - sharing the same struct fw_priv and lookup for multiple requests\n");
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return 1;
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}
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}
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tmp = __allocate_fw_priv(fw_name, fwc, dbuf, size);
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if (tmp)
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if (tmp && !(opt_flags & FW_OPT_NOCACHE))
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list_add(&tmp->list, &fwc->head);
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spin_unlock(&fwc->lock);
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@ -493,7 +496,8 @@ int assign_fw(struct firmware *fw, struct device *device,
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*/
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static int
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_request_firmware_prepare(struct firmware **firmware_p, const char *name,
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struct device *device, void *dbuf, size_t size)
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struct device *device, void *dbuf, size_t size,
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enum fw_opt opt_flags)
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{
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struct firmware *firmware;
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struct fw_priv *fw_priv;
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@ -511,7 +515,8 @@ _request_firmware_prepare(struct firmware **firmware_p, const char *name,
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return 0; /* assigned */
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}
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ret = alloc_lookup_fw_priv(name, &fw_cache, &fw_priv, dbuf, size);
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ret = alloc_lookup_fw_priv(name, &fw_cache, &fw_priv, dbuf, size,
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opt_flags);
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/*
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* bind with 'priv' now to avoid warning in failure path
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@ -571,7 +576,8 @@ _request_firmware(const struct firmware **firmware_p, const char *name,
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goto out;
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}
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ret = _request_firmware_prepare(&fw, name, device, buf, size);
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ret = _request_firmware_prepare(&fw, name, device, buf, size,
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opt_flags);
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if (ret <= 0) /* error or already assigned */
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goto out;
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