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Bug #1387

Updated by tuxillo over 6 years ago

Hello.

On recent -DEVELOPMENT ps command displays a non-intuitive error message

on a non-existent pid:

ps: kvm_getprocs: Bad address



Apparently the recent malloc reimplementation has changed malloc(3) family

so as malloc(0) now returns a pointer such that useracc() returns EFAULT

for it. kvm_getprocs() is one the functions affected by the new behavior

(no, I don't have the list of affected functions other than this

yet :). It used to return a non-NULL pointer and a 0 to *cnt, but now

it returns just NULL without affecting *cnt, so ps command displays the

error message. I think one way to fix is something like below (the fix

to the callers is taken from FreeBSD), but if we can restore the old

behavior of malloc(0), we don't need such fix.



%%%

diff --git a/bin/ps/ps.c b/bin/ps/ps.c

index 82e3e63..b66988a 100644

--- a/bin/ps/ps.c

+++ b/bin/ps/ps.c

@@ -385,7 +385,9 @@ main(int argc, char **argv)

/*

* select procs

*/

- if ((kp = kvm_getprocs(kd, what, flag, &nentries)) == NULL)

+ nentries = -1;

+ kp = kvm_getprocs(kd, what, flag, &nentries);

+ if ((kp == NULL && nentries > 0) || (kp != NULL && nentries < 0))

errx(1, "%s", kvm_geterr(kd));

if ((kinfo = malloc(nentries * sizeof(*kinfo))) == NULL)

err(1, NULL);

diff --git a/lib/libkvm/kvm_proc.c b/lib/libkvm/kvm_proc.c

index 1c39636..d0e388d 100644

--- a/lib/libkvm/kvm_proc.c

+++ b/lib/libkvm/kvm_proc.c

@@ -479,6 +479,10 @@ kvm_getprocs(kvm_t *kd, int op, int arg, int *cnt)

_kvm_syserr(kd, kd->program, "kvm_getprocs");

return (0);

}

+ if (size == 0) {

+ *cnt = 0;

+ return (0);

+ }

do {

size += size / 10;

kd->procbase = (struct kinfo_proc *)

diff --git a/usr.bin/fstat/fstat.c b/usr.bin/fstat/fstat.c

index 133fff7..7a8545d 100644

--- a/usr.bin/fstat/fstat.c

+++ b/usr.bin/fstat/fstat.c

@@ -241,7 +241,9 @@ main(int argc, char **argv)

if (kvm_nlist(kd, nl) != 0)

errx(1, "no namelist: %s", kvm_geterr(kd));

#endif

- if ((p = kvm_getprocs(kd, what, arg, &cnt)) == NULL)

+ cnt = -1;

+ p = kvm_getprocs(kd, what, arg, &cnt);

+ if ((p == NULL && cnt > 0) || (p != NULL && cnt < 0))

errx(1, "%s", kvm_geterr(kd));

if (nflg)

printf("USER %-*.*s %*.*s FD DEV %*.*s MODE SZ|DV R/W",

%%%

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