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kernel: make sure we wont run into the tos when copying exec() arguments

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in case the calling process changes its arguments under us, it could
happen that the final argument string lengths become bigger than
initially calculated. this is fine as we still make sure we wont
overflow the stack segment, but we could overrun into the tos
structure at the end of the stack. so change the limit to the
base of the tos, not the end of the stack segment.
This commit is contained in:
cinap_lenrek 2020-02-28 16:45:20 +01:00
parent ff3e0eeb22
commit adb36de077
1 changed files with 3 additions and 1 deletions
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4
sys/src/9/port/sysproc.c
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@ -466,8 +466,10 @@ sysexec(va_list list)
if(indir)
e = strchr(a, 0);
else {
if(charp >= (char*)tos)
error(Ebadarg);
validaddr((uintptr)a, 1, 0);
e = vmemchr(a, 0, (char*)tstk - charp);
e = vmemchr(a, 0, (char*)tos - charp);
if(e == nil)
error(Ebadarg);
}