https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=196110
Bug ID: 196110
Summary: [patch] procstat shows wrong stack nx information in
ELF auxv mode
Product: Base System
Version: 11.0-CURRENT
Hardware: amd64
OS: Any
Status: New
Severity: Affects Many People
Priority: ---
Component: bin
Assignee: [email protected]
Reporter: [email protected]
Created attachment 150736
--> https://bugs.freebsd.org/bugzilla/attachment.cgi?id=150736&action=edit
Patch for procstat_auxv.c
The ELF auxiliary vector displayed by `procstat -x` contains
information about whether or not the stack for that process is
executable or not.
This information is currently reversed, showing executable
when nxstack is enabled. It can be reproduced quite easily:
# sysctl kern.elf64.nxstack
kern.elf64.nxstack: 1
# procstat -x $$ | grep AT_STACKPROT
1471 csh AT_STACKPROT EXECUTABLE
After disabling nxstack, new processes show nonexecutable.
# sysctl kern.elf64.nxstack=0
kern.elf64.nxstack: 1 -> 0
# sh -c 'procstat -x $$ | grep AT_STACKPROT'
1477 sh AT_STACKPROT NONEXECUTABLE
Looking at the procstat code, the displayed string labels are
reversed for the check. The bitwise and will return !0 if the
executable bit is set.
if ((auxv[i].a_un.a_val & VM_PROT_EXECUTE) != 0)
PRINT(AT_STACKPROT, %s, "NONEXECUTABLE");
else
PRINT(AT_STACKPROT, %s, "EXECUTABLE");
break;
Attached is a simple patch to switch the labels.
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