From: Rishabh Bhatnagar rishabhb@codeaurora.org

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 ---

This has been tested with the self test firmware scrip and found no regressions.

drivers/base/firmware_loader/main.c | 30 +++++++++++++++++------------ 1 file changed, 18 insertions(+), 12 deletions(-)

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;