[Cin] unaligned load in bctheme

[Andrew Randrianasulu]

вс, 4 дек. 2022 г., 03:39 Phyllis Smith <phylsmith2017 at gmail.com>:

>
>> so i tried to instrument cingg to see if  she does any unaligned access
>>
>>
>> I added
>>
>>
>> diff --git a/cinelerra-5.1/guicast/Makefile
>> b/cinelerra-5.1/guicast/Makefile
>> index 04d5a2e5..b724c668 100644
>> --- a/cinelerra-5.1/guicast/Makefile
>> +++ b/cinelerra-5.1/guicast/Makefile
>> @@ -116,6 +116,7 @@ UTILS = $(OBJDIR)/bootstrap $(OBJDIR)/pngtoh
>> $(OBJDIR)/pngto
>> raw
>>  BCXFER = xfer/$(OBJDIR)/xfer.stamp
>>
>>  CFLAGS += $(static_incs)
>> +CFLAGS += -Wall -fsanitize=alignment
>>
>>  $(shell echo $(CFLAGS) > $(OBJDIR)/c_flags)
>>  $(shell echo $(OBJS) > $(OBJDIR)/objs)
>>
>>
>> and same -fsanitize=alignment to LDFLAGS env. variable before make.
>>
>
> On 4 different systems I was only able to include in guicast/Makefile, the
> CFLAGS += $(-fsanitize=alignment) and set the LDFLAGS environment variable
> to -fsanitize=alignment in order to compile.  But when I ran bin/cin I
> never got any errors of the type "bctheme.C:458:15: runtime error: load of
> misaligned address".  This was Fedora 32, Ubuntu 16, Debian 32-bit 9.1, and
> Debian 11.0.  I only loaded a file, played a little of it, and added a
> plugin as a test (maybe there was something in particular I should have
> tried?)
>


no, it was right on startup on Slackware 15.0 (mostly) 32-bit over 64-bit
kernel....

I'll try on ppc32 machine hopefully soon (ppc/sparc/alpha said to be much
more sensitive to such errors)



>>
>> so patch below fixes this error.
>>
>> Can you please test it on various arches and distros?
>>
>>
>> diff --git a/cinelerra-5.1/guicast/bctheme.C
>> b/cinelerra-5.1/guicast/bctheme.C
>> index 1ec64c7f..9addf9f7 100644
>> --- a/cinelerra-5.1/guicast/bctheme.C
>> +++ b/cinelerra-5.1/guicast/bctheme.C
>> @@ -455,7 +455,10 @@ void BC_Theme::overlay(VFrame *dst, VFrame *src, int
>> in_x1, int in_x2, int shift
>>
>>  void BC_Theme::set_data(unsigned char *ptr)
>>  {
>> -       int hdr_sz = *(int*)ptr - sizeof(int);
>> +       //int hdr_sz = *(int*)ptr - sizeof(int);
>> +       int hdr_sz = 0;
>> +       memcpy(&hdr_sz, ptr, sizeof(int));
>> +       hdr_sz -= sizeof(int);
>>         unsigned char *cp = ptr + sizeof(int);
>>         unsigned char *dp = cp + hdr_sz;
>>         int start_item = images.size();
>> lines 7-28/28 (END)
>>
>> Next I added the above patch, and all 4 systems compiled and ran the same
> limited set of commands to load and play a video file.  So it seems OK to
> check into GIT.  Just to verify, only the bctheme.C patch should be checked
> in - right?
>
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