Possible overflow bug?

Chris Rapier rapier at psc.edu
Wed Jun 7 02:02:11 AEST 2023


While doing some related work I built openssh 9.3p1 with 
-fsanitize=address and this came up during compilation.

In file included from /usr/include/string.h:535,
                  from kex.c:34:
In function 'explicit_bzero',
     inlined from 'kex_free_newkeys' at kex.c:743:2:
/usr/include/bits/string_fortified.h:72:3: warning: 
'__explicit_bzero_chk' writing 48 bytes into a region of size 8 
overflows the destination [-Wstringop-overflow=]
    72 |   __explicit_bzero_chk (__dest, __len, __glibc_objsize0 (__dest));
       |   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included from kex.c:53:
kex.h: In function 'kex_free_newkeys':
kex.h:116:18: note: destination object 'name' of size 8
   116 |         char    *name;
       |                  ^~~~
/usr/include/bits/string_fortified.h:66:6: note: in a call to function 
'__explicit_bzero_chk' declared with attribute 'access (write_only, 1, 2)'
    66 | void __explicit_bzero_chk (void *__dest, size_t __len, size_t 
__destlen)

Not sure if this is a real problem or not but I thought I'd pass it over 
just in case.

Chris


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