Skip to content

Fix nasa/cFS#945: Harden CS_OneShotCmd against DoS via secondary memory validation #122

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
Shrey-N wants to merge 4 commits into
base: main
Choose a base branch
from
Open

Fix nasa/cFS#945: Harden CS_OneShotCmd against DoS via secondary memory validation #122

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
4 commits
Select commit Hold shift + click to select a range
8b9acc6
Add event ID for oneshot checksum memory range error
Shrey-N Mar 7, 2026
42f87e5
Declare CS_VerifyAddressRange utility function
Shrey-N Mar 7, 2026
227ce4e
Implementing CS_VerifyAddressRange with boundary check overflow prote…
Shrey-N Mar 7, 2026
be4a6b4
Addition with secondary validation in CS_OneShotCmd
Shrey-N Mar 7, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
4 changes: 4 additions & 0 deletions fsw/inc/cs_eventids.h
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -1997,6 +1997,10 @@
*/
#define CS_VAL_TABLES_DEF_TBL_LONG_NAME_ERR_EID 155

/**
* \brief CS Oneshot Checksum Failed Memory Range Validation Event ID
*/
#define CS_ONESHOT_MEMRANGE_ERR_EID 156
/**@}*/

#endif
31 changes: 23 additions & 8 deletions fsw/src/cs_cmds.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -472,6 +472,28 @@ CFE_Status_t CS_OneShotCmd(const CS_OneShotCmd_t *CmdPtr)
/* validate size and address */
Status = CFE_PSP_MemValidateRange(CmdPtr->Payload.Address, CmdPtr->Payload.Size, CFE_PSP_MEM_ANY);

if (Status == CFE_SUCCESS)
{
/* Perform application-level secondary validation */
Status = CS_VerifyAddressRange(CmdPtr->Payload.Address, CmdPtr->Payload.Size);

if (Status != CFE_SUCCESS)
{
CFE_EVS_SendEvent(CS_ONESHOT_MEMRANGE_ERR_EID, CFE_EVS_EventType_ERROR,
"OneShot checksum failed, address range not in a permitted memory region: 0x%08X",
(unsigned int)Status);

CS_AppData.HkPacket.Payload.CmdErrCounter++;
}
}
else
{
CFE_EVS_SendEvent(CS_ONESHOT_MEMVALIDATE_ERR_EID, CFE_EVS_EventType_ERROR,
"OneShot checksum failed, CFE_PSP_MemValidateRange returned: 0x%08X", (unsigned int)Status);

CS_AppData.HkPacket.Payload.CmdErrCounter++;
}

if (Status == CFE_SUCCESS)
{
if (CS_AppData.HkPacket.Payload.RecomputeInProgress == false &&
Expand Down Expand Up @@ -508,7 +530,7 @@ CFE_Status_t CS_OneShotCmd(const CS_OneShotCmd_t *CmdPtr)
else /* child task creation failed */
{
CFE_EVS_SendEvent(CS_ONESHOT_CREATE_CHDTASK_ERR_EID, CFE_EVS_EventType_ERROR,
"OneShot checkum failed, CFE_ES_CreateChildTask returned: 0x%08X",
"OneShot checksum failed, CFE_ES_CreateChildTask returned: 0x%08X",
(unsigned int)Status);

CS_AppData.HkPacket.Payload.CmdErrCounter++;
Expand All @@ -524,13 +546,6 @@ CFE_Status_t CS_OneShotCmd(const CS_OneShotCmd_t *CmdPtr)

CS_AppData.HkPacket.Payload.CmdErrCounter++;
}
} /* end if CFE_PSP_MemValidateRange */
else
{
CFE_EVS_SendEvent(CS_ONESHOT_MEMVALIDATE_ERR_EID, CFE_EVS_EventType_ERROR,
"OneShot checksum failed, CFE_PSP_MemValidateRange returned: 0x%08X", (unsigned int)Status);

CS_AppData.HkPacket.Payload.CmdErrCounter++;
}

return CFE_SUCCESS;
Expand Down
79 changes: 79 additions & 0 deletions fsw/src/cs_utils.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -1148,3 +1148,82 @@ bool CS_CheckRecomputeOneshot(void)
}
return Result;
}

/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
/* */
/* Verifies that an address range is safe to access */
/* */
/* * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * */
CFE_Status_t CS_VerifyAddressRange(cpuaddr StartAddress, size_t Size)
{
CFE_Status_t Status = CS_TABLE_ERROR;
CS_Res_EepromMemory_Table_Entry_t *ResultsEntry;
uint32 Loop;

/* Check CFE core segment */
ResultsEntry = CS_GetCfeCoreCodeSegResTable();
if (ResultsEntry != NULL && ResultsEntry->State != CS_ChecksumState_EMPTY)
{
if (StartAddress >= ResultsEntry->StartAddress &&
Size <= ResultsEntry->NumBytesToChecksum &&
(StartAddress - ResultsEntry->StartAddress) <= (ResultsEntry->NumBytesToChecksum - Size))
{
Status = CFE_SUCCESS;
}
}

if (Status != CFE_SUCCESS)
{
/* Check OS core segment */
ResultsEntry = CS_GetOSCodeSegResTable();
if (ResultsEntry != NULL && ResultsEntry->State != CS_ChecksumState_EMPTY)
{
if (StartAddress >= ResultsEntry->StartAddress &&
Size <= ResultsEntry->NumBytesToChecksum &&
(StartAddress - ResultsEntry->StartAddress) <= (ResultsEntry->NumBytesToChecksum - Size))
{
Status = CFE_SUCCESS;
}
}
}

if (Status != CFE_SUCCESS)
{
/* Check Memory table */
for (Loop = 0; Loop < CS_MAX_NUM_MEMORY_TABLE_ENTRIES; Loop++)
{
ResultsEntry = CS_GetMemoryResEntry(Loop);
if (ResultsEntry != NULL && ResultsEntry->State != CS_ChecksumState_EMPTY)
{
if (StartAddress >= ResultsEntry->StartAddress &&
Size <= ResultsEntry->NumBytesToChecksum &&
(StartAddress - ResultsEntry->StartAddress) <= (ResultsEntry->NumBytesToChecksum - Size))
{
Status = CFE_SUCCESS;
break;
}
}
}
}

if (Status != CFE_SUCCESS)
{
/* Check EEPROM table */
for (Loop = 0; Loop < CS_MAX_NUM_EEPROM_TABLE_ENTRIES; Loop++)
{
ResultsEntry = CS_GetEepromResEntry(Loop);
if (ResultsEntry != NULL && ResultsEntry->State != CS_ChecksumState_EMPTY)
{
if (StartAddress >= ResultsEntry->StartAddress &&
Size <= ResultsEntry->NumBytesToChecksum &&
(StartAddress - ResultsEntry->StartAddress) <= (ResultsEntry->NumBytesToChecksum - Size))
{
Status = CFE_SUCCESS;
break;
}
}
}
}

return Status;
}
5 changes: 5 additions & 0 deletions fsw/src/cs_utils.h
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -471,6 +471,11 @@ bool CS_CheckRecomputeOneshot(void);
*/
CS_ChecksumState_Enum_t CS_SetDefEntryState(CS_TableWrapper_t *tw, void *EntryPtr, CS_ChecksumState_Enum_t NewState);

/**
* \brief Verifies that an address range is safe to access
*/
CFE_Status_t CS_VerifyAddressRange(cpuaddr StartAddress, size_t Size);

/**
* \brief Checks if the definition table matches the given name
*
Expand Down