bin/184950: swapon aborts on gdbe device

[Jilles Tjoelker]

The following reply was made to PR bin/184950; it has been noted by GNATS.

From: Jilles Tjoelker <jilles at stack.nl>
To: bug-followup at FreeBSD.org, hsn at sendmail.cz
Cc:  
Subject: Re: bin/184950: swapon aborts on gdbe device
Date: Sat, 21 Dec 2013 00:11:18 +0100

 In PR bin/184950, you wrote:
 > i have system configured for encrypted swap gdbe_swap_enabled=YES
 
 > in fstab
 > /dev/ada0s1b.bde none swap sw 0 0
 
 > in backtrace:
 
 > function swap_on_off() fails at 0x0804a756 which triggers stack
 > checking routines from libc __stack_chk_fail() printing stack
 > underflow
 
 This bug is probably not that conspicuous because most people use geli
 instead of gbde for disk encryption.
 
 I looked at the code anyway, and I think the compiler and the buffer
 overflow detector are perfectly right. On platforms where char is signed
 (i.e. most, with the notable exception of arm), the sprintf() call in
 swap_on_off_gbde() may write 9 instead of the expected 3 bytes. There is
 a probability of 12.5% that the last 3 chars are all non-negative and
 therefore no buffer overflow occurs.
 
 The below patch should fix it. I have only tested that it compiles.
 
 Index: sbin/swapon/swapon.c
 ===================================================================
 --- sbin/swapon/swapon.c	(revision 259508)
 +++ sbin/swapon/swapon.c	(working copy)
 @@ -266,7 +266,8 @@ static const char *
  swap_on_off_gbde(const char *name, int doingall)
  {
  	const char *ret;
 -	char pass[64 * 2 + 1], bpass[64];
 +	char pass[64 * 2 + 1];
 +	unsigned char bpass[64];
  	char *dname;
  	int i, error;
  
 
 -- 
 Jilles Tjoelker