Re: What is the suggested way to use a C compiler with sanitizers?

[christos%astron.com@localhost (Christos Zoulas)]

In article <527159918.27358.1480598518733.JavaMail.ngmail%webmail18.arcor-online.net@localhost>,
Carsten Kunze  <carsten.kunze%arcor.de@localhost> wrote:
>Hello,
>
>if one wants to use the sanitizer features of the C compiler, what is
>the suggested way?
>
>If I e.g. compile and link with options
>
>-O2  -g -O0 -fno-omit-frame-pointer -fno-optimize-sibling-calls -Wall
>-Wextra -Wsign-compare -Wcast-align -Wcast-qual -Wmissing-prototypes
>-Wunused-parameter -Wunused-function -Wshadow -fno-common
>-fsanitize=address -fsanitize=undefined -fsanitize=float-divide-by-zero
>-fsanitize=float-cast-overflow
>
>(-O2 is from CFLAGS which should be reset by -O0)
>
>I get something like
>
>ui.c:2017:11: runtime error: member access within misaligned address
>0xbebebebebebebebe for type 'struct filediff', which requires 8 byte
>alignment
>0xbebebebebebebebe: note: pointer points here                           
>test 
><memory cannot be printed>                                              
>
>ASAN:SIGSEGV                                                            
>
>=================================================================       
>
>==1372==ERROR: AddressSanitizer: SEGV on unknown address 0x72d42a8a5000
>(pc 0x0000004229c5 bp 0x7f7fff49c710 sp 0x7f7fff49c460 T0)
>    #0 0x4229c4  (<unknown module>)                                     
>
>    #1 0x421dd7  (<unknown module>)                                     
>
>    #2 0x44b9be  (<unknown module>)                                     
>
>    #3 0x42a329  (<unknown module>)                                     
>
>    #4 0x4488ad  (<unknown module>)                                     
>
>    #5 0x413a90  (<unknown module>)                                     
>
>    #6 0x410e02  (<unknown module>)                                     
>
>    #7 0x4054ae  (<unknown module>)                                     
>
>    #8 0x4044ba  (<unknown module>)                                     
>
>                                                                        
>
>AddressSanitizer can not provide additional info.                       
>
>SUMMARY: AddressSanitizer: SEGV ??:0 ??                                 
>
>==1372==ABORTING
>
>on errors.  What needs to be configured to make the symbolizer work? 
>(Binary is not stripped.)

You need an external symbolizer... By default it runs llvm-symbolizer,
but you can make it use addr2line by setting:

ASAN_OPTIONS=allow_addr2line=true

But then, it looks for libasan.so.1 in the current working directory, and
you can ln -s /usr/lib/libasan.so.1 ., after that it finds the symbols in
the library but not in the main program, saying "unknown module".

christos