[PATCH edk2-platforms v1 1/1] Platform/ARM: Fix uninitialized variable in RunAxf

[PATCH edk2-platforms v1 1/1] Platform/ARM: Fix uninitialized variable in RunAxf

[Sami Mujawar]

RunAxf is a shell command used for running an Axf
file. The ShellDynCmdRunAxfHandler() loads an ELF
file or one processed by the Flashloader. It
calls the appropriate loaders to load the file
in memory and to obtain the entry point address.

The first argument to RunAxfPivot() is the entry
point address for the image to execute. The patch
https://github.com/tianocore/edk2-platforms/commit/996047695a06167a918b07b22fcd0fbd0def5da6
changes set/way cache maintenance operations
to by-VA operation. This patch however introduced
an error: 'variable StartElf is not initialized'.

Since, StartElf is the first argument to
RunAxfPivot(), which is expected to be the entry
point address; RunAxfPivot() would end up branching
to an invalid address resulting in a crash.

Therefore, initialize StartElf to the entry point
address before calling RunAxfPivot().

Signed-off-by: Sami Mujawar <sami.mujawar@arm.com>
---

The changes can be seen at:
https://github.com/samimujawar/edk2-platforms/tree/769_runaxf_fix_uninit_var_v1

Notes:
    V1:
    - Fix uninitialized variable usage in RunAxf                    [SAMI]

 Platform/ARM/Library/ArmShellCmdRunAxf/RunAxf.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/Platform/ARM/Library/ArmShellCmdRunAxf/RunAxf.c b/Platform/ARM/Library/ArmShellCmdRunAxf/RunAxf.c
index dbad50ae866ac91d796b70ce7eed1dda4ab99957..d23739ad38d922ea16b5dc615604e9016c30fcbe 100644
--- a/Platform/ARM/Library/ArmShellCmdRunAxf/RunAxf.c
+++ b/Platform/ARM/Library/ArmShellCmdRunAxf/RunAxf.c
@@ -2,7 +2,7 @@
 *
 *  Shell command for launching AXF files.
 *
-*  Copyright (c) 2014, ARM Limited. All rights reserved.
+*  Copyright (c) 2014 - 2020, ARM Limited. All rights reserved.
 *
 *  SPDX-License-Identifier: BSD-2-Clause-Patent
 *
@@ -315,6 +315,7 @@ ShellDynCmdRunAxfHandler (
       //
       WriteBackDataCacheRange (LoadedImage->ImageBase, LoadedImage->ImageSize);
 
+      StartElf = (ELF_ENTRYPOINT)Entrypoint;
       RunAxfPivot (StartElf, 0, 0, 0, 0);
 
       // We should never get here.. But if we do, spin..
-- 
'Guid(CE165669-3EF3-493F-B85D-6190EE5B9759)'

Re: [PATCH edk2-platforms v1 1/1] Platform/ARM: Fix uninitialized variable in RunAxf

[Ard Biesheuvel]

On Fri, 3 Apr 2020 at 18:05, Sami Mujawar <sami.mujawar@arm.com> wrote:
>
> RunAxf is a shell command used for running an Axf
> file. The ShellDynCmdRunAxfHandler() loads an ELF
> file or one processed by the Flashloader. It
> calls the appropriate loaders to load the file
> in memory and to obtain the entry point address.
>
> The first argument to RunAxfPivot() is the entry
> point address for the image to execute. The patch
> https://github.com/tianocore/edk2-platforms/commit/996047695a06167a918b07b22fcd0fbd0def5da6
> changes set/way cache maintenance operations
> to by-VA operation. This patch however introduced
> an error: 'variable StartElf is not initialized'.
>
> Since, StartElf is the first argument to
> RunAxfPivot(), which is expected to be the entry
> point address; RunAxfPivot() would end up branching
> to an invalid address resulting in a crash.
>
> Therefore, initialize StartElf to the entry point
> address before calling RunAxfPivot().
>
> Signed-off-by: Sami Mujawar <sami.mujawar@arm.com>

Reviewed-by: Ard Biesheuvel <ard.biesheuvel@arm.com>

Pushed as 5780623dc5c8..1d59c5b912d9

Thanks Sami


> ---
>
> The changes can be seen at:
> https://github.com/samimujawar/edk2-platforms/tree/769_runaxf_fix_uninit_var_v1
>
> Notes:
>     V1:
>     - Fix uninitialized variable usage in RunAxf                    [SAMI]
>
>  Platform/ARM/Library/ArmShellCmdRunAxf/RunAxf.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/Platform/ARM/Library/ArmShellCmdRunAxf/RunAxf.c b/Platform/ARM/Library/ArmShellCmdRunAxf/RunAxf.c
> index dbad50ae866ac91d796b70ce7eed1dda4ab99957..d23739ad38d922ea16b5dc615604e9016c30fcbe 100644
> --- a/Platform/ARM/Library/ArmShellCmdRunAxf/RunAxf.c
> +++ b/Platform/ARM/Library/ArmShellCmdRunAxf/RunAxf.c
> @@ -2,7 +2,7 @@
>  *
>  *  Shell command for launching AXF files.
>  *
> -*  Copyright (c) 2014, ARM Limited. All rights reserved.
> +*  Copyright (c) 2014 - 2020, ARM Limited. All rights reserved.
>  *
>  *  SPDX-License-Identifier: BSD-2-Clause-Patent
>  *
> @@ -315,6 +315,7 @@ ShellDynCmdRunAxfHandler (
>        //
>        WriteBackDataCacheRange (LoadedImage->ImageBase, LoadedImage->ImageSize);
>
> +      StartElf = (ELF_ENTRYPOINT)Entrypoint;
>        RunAxfPivot (StartElf, 0, 0, 0, 0);
>
>        // We should never get here.. But if we do, spin..
> --
> 'Guid(CE165669-3EF3-493F-B85D-6190EE5B9759)'
>