Messages in this thread Patch in this message | | | From | Rishabh Bhatnagar <> | Subject | [PATCH] firmware: Fix security issue with request_firmware_into_buf() | Date | Wed, 1 Aug 2018 16:25:56 -0700 |
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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")
Signed-off-by: Vikram Mulukutla <markivx@codeaurora.org> Signed-off-by: Rishabh Bhatnagar <rishabhb@codeaurora.org> --- 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 0943e70..b3c0498 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 @@ int assign_fw(struct firmware *fw, struct device *device, 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 @@ static void fw_abort_batch_reqs(struct firmware *fw) 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; -- The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project
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