On Thu, 17 Mar 2022 20:56:34 GMT, Mikael Vidstedt <mik...@openjdk.org> wrote:
> Note: this PR replaces the one I messed up earlier.
>
> Background, from JBS:
>
> src/java.base/share/native/libverify/check_code.c: In function
> 'read_all_code':
> src/java.base/share/native/libverify/check_code.c:942:5: error: 'lengths' may
> be used uninitialized [-Werror=maybe-uninitialized]
> 942 | check_and_push(context, lengths, VM_MALLOC_BLK);
> | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> src/java.base/share/native/libverify/check_code.c:4145:13: note: by argument
> 2 of type 'const void *' to 'check_and_push' declared here
> 4145 | static void check_and_push(context_type *context, const void *ptr, int
> kind)
> | ^~~~~~~~~~~~~~
>
> Because the second argument of check_and_push is "const void*" GCC assumes
> that the malloc:ed data, which has not yet been initialized, will not be/can
> not be modified later which in turn suggests it may be used without ever
> being initialized.
>
> The same general issue was addressed in JDK-8266168, presumably for GCC 11.1.
>
> Details:
>
> Instead of sprinkling more calloc calls around or using pragmas/gcc
> attributes I chose to change the check_and_push function to take a
> (non-const) void* argument, and provide a new wrapper function
> check_and_push_const which handles the const argument case. For the
> (non-const) VM_MALLOC_BKP that means the pointer never needs to go through a
> const conversion.
>
> To avoid having multiple ways of solving the same problem I also chose to
> revert the change made in JDK-8266168, reverting the calloc back to a malloc
> call.
>
> Testing:
>
> tier1 + builds-tier{2,3,4,5}
This pull request has now been integrated.
Changeset: d8893fad
Author: Mikael Vidstedt <mik...@openjdk.org>
URL:
https://git.openjdk.java.net/jdk/commit/d8893fad23d1ee6841336b96c34599643edb81ce
Stats: 30 lines in 1 file changed: 9 ins; 0 del; 21 mod
8283059: Uninitialized warning in check_code.c with GCC 11.2
Reviewed-by: dholmes
-------------
PR: https://git.openjdk.java.net/jdk/pull/7859
