strcmp used instead of ACPI_COMPARE_NAMESEG

[BenjaminBerg]

In aslmethod.c there are two cases where strcmp is used. However, these should be strncmp or better ACPI_COMPARE_NAMESEG, resulting in the branches to be never reached.

> ./acpica/source/compiler/aslmethod.c: if (!strcmp (METHOD_NAME__HID, Op->Asl.NameSeg))
> ./acpica/source/compiler/aslmethod.c: else if (!strcmp (METHOD_NAME__CID, Op->Asl.NameSeg))

This issue was found by Red Hat's compiler team recompiling the package against gcc-10.

[Colin Ian King (colin-king)]

Thanks for reporting this issue. The ACPICA source is from the ACPICA project, do you mind build testing the original ACPICA source against gcc-10 and filing a bug against this at https://bugs.acpica.org if the same issue is found.

[BenjaminBerg (benjamin-sipsolutions)]

Reported upstream as https://bugs.acpica.org/show_bug.cgi?id=1504

[Colin Ian King (colin-king)]

Thanks Benjamin, much appreciated!

[Colin Ian King (colin-king)]

Which version of gcc-10 are you using? I can't reproduce this with http://kayari.org/gcc-latest/gcc-latest_10.0.0-20191027svn277495.deb

[BenjaminBerg (benjamin-sipsolutions)]

I don't know to be honest. Fedora also sets a number of hardening warnings/error flags, so quite likely, this only happens because of those.

I can ask for details, but they have not been provided to me so far. That said, I think the bug is actually quite obvious in this case, even if it may not be found with your compile flags.

[Colin Ian King (colin-king)]

OK. Just for reference, it would be useful to know the hardening flags so I can ensure fwts is built with these to try to catch these in the future.

[Colin Ian King (colin-king)]

Fix has landed in ACPICA, will bring it over to fwts now.

commit 3dcd13aa62e70294e194ebc0cf16dd33c90b17ab
Author: Robert Moore <email address hidden>
Date: Fri Nov 8 07:33:54 2019 -0800

    iASL: Use ACPI_COMPARE_NAMESEG instead of strcmp

    For _HID, _CID processing. Reported by Benjamin Berg
    (<email address hidden>).

diff --git a/source/compiler/aslmethod.c b/source/compiler/aslmethod.c
index 667eaaaf8..4b29fc9e7 100644
--- a/source/compiler/aslmethod.c
+++ b/source/compiler/aslmethod.c
@@ -586,7 +586,7 @@ MtMethodAnalysisWalkBegin (

         /* Special typechecking for _HID */

- if (!strcmp (METHOD_NAME__HID, Op->Asl.NameSeg))
+ if (ACPI_COMPARE_NAMESEG (METHOD_NAME__HID, Op->Asl.NameSeg))
         {
             Next = Op->Asl.Child->Asl.Next;
             AnCheckId (Next, ASL_TYPE_HID);
@@ -594,7 +594,7 @@ MtMethodAnalysisWalkBegin (

         /* Special typechecking for _CID */

- else if (!strcmp (METHOD_NAME__CID, Op->Asl.NameSeg))
+ else if (ACPI_COMPARE_NAMESEG (METHOD_NAME__CID, Op->Asl.NameSeg))
         {
             Next = Op->Asl.Child->Asl.Next;

[Colin Ian King (colin-king)]

Patch waiting for review on fwts-devel mailing list: https://lists.ubuntu.com/archives/fwts-devel/2019-November/011616.html