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Bug #1387

Updated by tuxillo about 7 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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