2024-02-08 12:36:19

by Auditya Bhattaram

Subject: [PATCH v3] soc: qcom: mdt_loader: Add Upperbounds check for program header access

hash_index is evaluated by looping phdrs till QCOM_MDT_TYPE_HASH
is found. Add an upperbound check to phdrs to access within elf size.

Fixes: 64fb5eb87d58 ("soc: qcom: mdt_loader: Allow hash to reside in any segment")
Cc: <[email protected]>
Signed-off-by: Auditya Bhattaram <[email protected]>
---
Changes in v3:
- Corrected wrong patch versioning in the Subject.
- Added error prints for Invalid access.
Link to v2 https://lore.kernel.org/linux-arm-msm/[email protected]/T/#t
Link to v1 https://lore.kernel.org/linux-arm-msm/[email protected]/T/#t
---
drivers/soc/qcom/mdt_loader.c | 5 +++++
1 file changed, 5 insertions(+)

diff --git a/drivers/soc/qcom/mdt_loader.c b/drivers/soc/qcom/mdt_loader.c
index 6f177e46fa0f..61e2377cc5c3 100644
--- a/drivers/soc/qcom/mdt_loader.c
+++ b/drivers/soc/qcom/mdt_loader.c
@@ -145,6 +145,11 @@ void *qcom_mdt_read_metadata(const struct firmware *fw, size_t *data_len,
if (phdrs[0].p_type == PT_LOAD)
return ERR_PTR(-EINVAL);

+ if (((size_t)(phdrs + ehdr->e_phnum)) > ((size_t)ehdr + fw->size)) {
+ dev_err(dev, "Invalid phdrs access: %s\n", fw_name);
+ return ERR_PTR(-EINVAL);
+ }
+
for (i = 1; i < ehdr->e_phnum; i++) {
if ((phdrs[i].p_flags & QCOM_MDT_TYPE_MASK) == QCOM_MDT_TYPE_HASH) {
hash_segment = i;
--
2.17.1

2024-02-08 14:45:23

by Mukesh Ojha

Subject: Re: [PATCH v3] soc: qcom: mdt_loader: Add Upperbounds check for program header access

On 2/8/2024 6:05 PM, Auditya Bhattaram wrote:
> hash_index is evaluated by looping phdrs till QCOM_MDT_TYPE_HASH
> is found. Add an upperbound check to phdrs to access within elf size.
>
> Fixes: 64fb5eb87d58 ("soc: qcom: mdt_loader: Allow hash to reside in any segment")
> Cc: <[email protected]>
> Signed-off-by: Auditya Bhattaram <[email protected]>
> ---
> Changes in v3:
> - Corrected wrong patch versioning in the Subject.
> - Added error prints for Invalid access.
> Link to v2 https://lore.kernel.org/linux-arm-msm/[email protected]/T/#t
> Link to v1 https://lore.kernel.org/linux-arm-msm/[email protected]/T/#t
> ---
> drivers/soc/qcom/mdt_loader.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/drivers/soc/qcom/mdt_loader.c b/drivers/soc/qcom/mdt_loader.c
> index 6f177e46fa0f..61e2377cc5c3 100644
> --- a/drivers/soc/qcom/mdt_loader.c
> +++ b/drivers/soc/qcom/mdt_loader.c
> @@ -145,6 +145,11 @@ void *qcom_mdt_read_metadata(const struct firmware *fw, size_t *data_len,
> if (phdrs[0].p_type == PT_LOAD)
> return ERR_PTR(-EINVAL);
>
> + if (((size_t)(phdrs + ehdr->e_phnum)) > ((size_t)ehdr + fw->size)) {

This change is valid only if somehow, ehdr->e_phnum gets corrupted or
changed via some engineering means and results in out-of-bounds access.

Acked-by: Mukesh Ojha <[email protected]>

> + dev_err(dev, "Invalid phdrs access: %s\n", fw_name);

Should it print ehdr->e_phnum as well to be more valid?

-Mukesh

> + return ERR_PTR(-EINVAL);
> + }
> +
> for (i = 1; i < ehdr->e_phnum; i++) {
> if ((phdrs[i].p_flags & QCOM_MDT_TYPE_MASK) == QCOM_MDT_TYPE_HASH) {
> hash_segment = i;
> --
> 2.17.1
>
>

2024-02-09 05:46:16

by Auditya Bhattaram

Subject: Re: [PATCH v3] soc: qcom: mdt_loader: Add Upperbounds check for program header access

On 2/8/2024 7:59 PM, Mukesh Ojha wrote:
>
>
> On 2/8/2024 6:05 PM, Auditya Bhattaram wrote:
>> hash_index is evaluated by looping phdrs till QCOM_MDT_TYPE_HASH
>> is found. Add an upperbound check to phdrs to access within elf size.
>>
>> Fixes: 64fb5eb87d58 ("soc: qcom: mdt_loader: Allow hash to reside in
>> any segment")
>> Cc: <[email protected]>
>> Signed-off-by: Auditya Bhattaram <[email protected]>
>> ---
>> Changes in v3:
>>   - Corrected wrong patch versioning in the Subject.
>>   - Added error prints for Invalid access.
>> Link to v2
>> https://lore.kernel.org/linux-arm-msm/[email protected]/T/#t
>> Link to v1
>> https://lore.kernel.org/linux-arm-msm/[email protected]/T/#t
>> ---
>>   drivers/soc/qcom/mdt_loader.c | 5 +++++
>>   1 file changed, 5 insertions(+)
>>
>> diff --git a/drivers/soc/qcom/mdt_loader.c
>> b/drivers/soc/qcom/mdt_loader.c
>> index 6f177e46fa0f..61e2377cc5c3 100644
>> --- a/drivers/soc/qcom/mdt_loader.c
>> +++ b/drivers/soc/qcom/mdt_loader.c
>> @@ -145,6 +145,11 @@ void *qcom_mdt_read_metadata(const struct
>> firmware *fw, size_t *data_len,
>>       if (phdrs[0].p_type == PT_LOAD)
>>           return ERR_PTR(-EINVAL);
>>
>> +    if (((size_t)(phdrs + ehdr->e_phnum)) > ((size_t)ehdr + fw->size)) {
>
> This change is valid only if somehow, ehdr->e_phnum gets corrupted or
> changed via some engineering means and results in out-of-bounds access.
>
> Acked-by: Mukesh Ojha <[email protected]>
>
>> +        dev_err(dev, "Invalid phdrs access: %s\n", fw_name);
>
> Should it print ehdr->e_phnum as well to be more valid?
>
> -Mukesh
>

Sure, planning to add fw->size as well.
dev_err(dev, "Invalid phdrs access for fw: %s, e_phnum: %hu, fw->size:
%zu \n", fw_name, ehdr->e_phnum, fw->size);

>> +        return ERR_PTR(-EINVAL);
>> +    }
>> +
>>       for (i = 1; i < ehdr->e_phnum; i++) {
>>           if ((phdrs[i].p_flags & QCOM_MDT_TYPE_MASK) ==
>> QCOM_MDT_TYPE_HASH) {
>>               hash_segment = i;
>> --
>> 2.17.1
>>
>>