The original implementation was using strncpy() with a truncation
length to an uninitialized stack buffer, leaving a string that
was only null terminated by luck.
While here, change to use no-copy semantics (no extra buffer) to
avoid buffer overflows altogether. exportfs already modifies argv
contents elsewhere, so this doesn't break anything anew.
Fixes: 4663c648 (exportfs: Support raw IPv6 addresses with "client:/path")
Signed-off-by: Todd Vierling <todd.vierling@xxxxxxxxxx>
Reviewed-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
---
utils/exportfs/exportfs.c | 18 ++++++++----------
1 file changed, 8 insertions(+), 10 deletions(-)
diff --git a/utils/exportfs/exportfs.c b/utils/exportfs/exportfs.c
index e7d1ac8..bdea12b 100644
--- a/utils/exportfs/exportfs.c
+++ b/utils/exportfs/exportfs.c
@@ -351,16 +351,15 @@ static int exportfs_generic(char *arg, char *options, int verbose)
static int exportfs_ipv6(char *arg, char *options, int verbose)
{
- char *path, *c, hname[NI_MAXHOST + strlen("/128")];
+ char *path, *c;
arg++;
c = strchr(arg, ']');
if (c == NULL)
return 1;
- strncpy(hname, arg, c - arg);
/* no colon means this is a wildcarded DNS hostname */
- if (strchr(hname, ':') == NULL)
+ if (memchr(arg, ':', c - arg) == NULL)
return exportfs_generic(--arg, options, verbose);
path = strstr(c, ":/");
@@ -370,9 +369,9 @@ static int exportfs_ipv6(char *arg, char *options, int verbose)
/* if there's anything between the closing brace and the
* path separator, it's probably a prefix length */
- strcat(hname, ++c);
+ memmove(c, c + 1, path - c);
- exportfs_parsed(hname, path, options, verbose);
+ exportfs_parsed(arg, path, options, verbose);
return 0;
}
@@ -458,16 +457,15 @@ static int unexportfs_generic(char *arg, int verbose)
static int unexportfs_ipv6(char *arg, int verbose)
{
- char *path, *c, hname[NI_MAXHOST + strlen("/128")];
+ char *path, *c;
arg++;
c = strchr(arg, ']');
if (c == NULL)
return 1;
- strncpy(hname, arg, c - arg);
/* no colon means this is a wildcarded DNS hostname */
- if (strchr(hname, ':') == NULL)
+ if (memchr(arg, ':', c - arg) == NULL)
return unexportfs_generic(--arg, verbose);
path = strstr(c, ":/");
@@ -477,9 +475,9 @@ static int unexportfs_ipv6(char *arg, int verbose)
/* if there's anything between the closing brace and the
* path separator, it's probably a prefix length */
- strcat(hname, ++c);
+ memmove(c, c + 1, path - c);
- unexportfs_parsed(hname, path, verbose);
+ unexportfs_parsed(arg, path, verbose);
return 0;
}
--
1.8.3.1
--
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