On 14/01/2020 16:53, Paul-Antoine Arras wrote:
I'm stumbling upon a weird message from Valgrind when run on my
application as follows:
$ valgrind --vgdb=yes --vgdb-error=0 --undef-value-errors=no $my_app
So Valgrind reports:
==1644== Thread 9:
==1644== Invalid read of size 8
==1644== at 0x4A39B40: PR_int__give_lang_env_for_slave (PR__int.c:348)
==1644== Address 0x12d152c8 is 24 bytes inside a block of size 104 alloc'd
==1644== at 0x483577F: malloc (vg_replace_malloc.c:309)
==1644== by 0x4A3C4B4: [...]
I struggle to understand how a read into a block of properly alloc'd
memory can be invalid, given that the application doesn't use client
requests.
To be sure, I double-checked the status of the entire buffer under vgdb:
(gdb) mo xb 0x12d152b0 104
[...]
Address 0x12D152B0 len 104 has 104 bytes unaddressable
How can a block of dynamically-allocated memory be marked unaddressable
without having been freed?
By using the VALGRIND_MAKE_MEM_NOACCESS macro.
Tom
--
Tom Hughes (t...@compton.nu)
http://compton.nu/
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