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Fix (for the second time) kvm_getprocs() for the case where no

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processes match the given criteria.  Since revision 1.60 of malloc.c,
malloc() and friends return an invalid pointer when given a size of 0.
kvm_getprocs() uses sysctl() with a NULL oldp argument to get an
initial size, but does not check whether it's 0 before passing it to
realloc() (via _kvm_realloc()).  Before the aforementioned malloc()
change, this resulted in a minimal allocation made and a valid poitner
returned, but now results in an invalid, but non-NULL, pointer being
returned.  When this is passed to sysctl(), the latter returns EFAULT
(as it should).
This commit is contained in:
dd 2002-04-07 04:47:58 +00:00
parent 9c4d69ea42
commit 4abe7f3290
1 changed files with 26 additions and 0 deletions
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26
lib/libkvm/kvm_proc.c
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@ -409,6 +409,25 @@ kvm_getprocs(kd, op, arg, cnt)
_kvm_syserr(kd, kd->program, "kvm_getprocs");
return (0);
}
/*
* We can't continue with a size of 0 because we pass
* it to realloc() (via _kvm_realloc()), and passing 0
* to realloc() results in undefined behavior.
*/
if (size == 0) {
/*
* XXX: We should probably return an invalid,
* but non-NULL, pointer here so any client
* program trying to dereference it will
* crash. However, _kvm_freeprocs() calls
* free() on kd->procbase if it isn't NULL,
* and free()'ing a junk pointer isn't good.
* Then again, _kvm_freeprocs() isn't used
* anywhere . . .
*/
kd->procbase = _kvm_malloc(kd, 1);
goto liveout;
}
do {
size += size / 10;
kd->procbase = (struct kinfo_proc *)
@ -422,6 +441,12 @@ kvm_getprocs(kd, op, arg, cnt)
_kvm_syserr(kd, kd->program, "kvm_getprocs");
return (0);
}
/*
* We have to check the size again because sysctl()
* may "round up" oldlenp if oldp is NULL; hence it
* might've told us that there was data to get when
* there really isn't any.
*/
if (size > 0 &&
kd->procbase->ki_structsize != sizeof(struct kinfo_proc)) {
_kvm_err(kd, kd->program,
@ -430,6 +455,7 @@ kvm_getprocs(kd, op, arg, cnt)
kd->procbase->ki_structsize);
return (0);
}
liveout:
nprocs = size == 0 ? 0 : size / kd->procbase->ki_structsize;
} else {
struct nlist nl[4], *p;