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w: Prevent out-of-bounds reads in print_display_or_interface().

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They occur if disp or tmp reaches host + len: add checks. Also, constify
everything.
This commit is contained in:
Qualys Security Advisory 1970-01-01 00:00:00 +00:00 committed by Craig Small
parent e1eaf83b34
commit 3a437012f0
1 changed files with 9 additions and 9 deletions
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18
w.c
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@ -113,21 +113,22 @@ static void print_host(const char *restrict host, int len, const int fromlen)
/* This routine prints the display part of the host or IPv6 link address interface */ /* This routine prints the display part of the host or IPv6 link address interface */
static void print_display_or_interface(const char *restrict host, int len, int restlen) static void print_display_or_interface(const char *restrict host, int len, int restlen)
{ {
char *disp,*tmp; const char *const end = host + (len > 0 ? len : 0);
const char *disp, *tmp;
if (restlen <= 0) return; /* not enough space for printing anything */ if (restlen <= 0) return; /* not enough space for printing anything */
/* search for a collon (might be a display) */ /* search for a collon (might be a display) */
disp = (char *)host; disp = host;
while ( (disp < (host + len)) && (*disp != ':') && isprint(*disp) ) disp++; while ( (disp < end) && (*disp != ':') && isprint(*disp) ) disp++;
/* colon found */ /* colon found */
if (*disp == ':') { if (disp < end && *disp == ':') {
/* detect multiple colons -> IPv6 in the host (not a display) */ /* detect multiple colons -> IPv6 in the host (not a display) */
tmp = disp+1; tmp = disp+1;
while ( (tmp < (host + len)) && (*tmp != ':') && isprint(*tmp) ) tmp++; while ( (tmp < end) && (*tmp != ':') && isprint(*tmp) ) tmp++;
if (*tmp != ':') { /* multiple colons not found - it's a display */ if (tmp >= end || *tmp != ':') { /* multiple colons not found - it's a display */
/* number of chars till the end of the input field */ /* number of chars till the end of the input field */
len -= (disp - host); len -= (disp - host);
@ -149,9 +150,9 @@ static void print_display_or_interface(const char *restrict host, int len, int r
} else { /* multiple colons found - it's an IPv6 address */ } else { /* multiple colons found - it's an IPv6 address */
/* search for % (interface separator in case of IPv6 link address) */ /* search for % (interface separator in case of IPv6 link address) */
while ( (tmp < (host + len)) && (*tmp != '%') && isprint(*tmp) ) tmp++; while ( (tmp < end) && (*tmp != '%') && isprint(*tmp) ) tmp++;
if (*tmp == '%') { /* interface separator found */ if (tmp < end && *tmp == '%') { /* interface separator found */
/* number of chars till the end of the input field */ /* number of chars till the end of the input field */
len -= (tmp - host); len -= (tmp - host);
@ -170,7 +171,6 @@ static void print_display_or_interface(const char *restrict host, int len, int r
fputc('-', stdout); fputc('-', stdout);
} }
} }
} }
} }