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lib/: Remove off-by-one bugs in calls to strncpy(3)

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We're not even zeroing the last byte after this call.  This was a
completely gratuitous truncation of one byte, and the resulting
character array still wasn't guaranteed to be null terminated, because
strncpy(3) can't do that.

Just to clarify, none of these structures needed zeroing, as they are
treated as null-padded fixed-size character arrays.  Calling strncpy(3)
was actually the correct call, and the only problem was unnecessarily
truncating strings by one byte more than necessary.

Cc: Matthew House <mattlloydhouse@gmail.com>
Signed-off-by: Alejandro Colomar <alx@kernel.org>
This commit is contained in:
Alejandro Colomar
2023-11-15 22:14:18 +01:00
committed by Serge Hallyn
parent 81f0e6a30f
commit 07ab1af55c
2 changed files with 5 additions and 5 deletions
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2
lib/log.c
View File

@@ -82,7 +82,7 @@ void dolastlog (
newlog.ll_time = ll_time;
STRTCPY(newlog.ll_line, line);
#if HAVE_LL_HOST
strncpy (newlog.ll_host, host, sizeof (newlog.ll_host) - 1);
strncpy(newlog.ll_host, host, sizeof(newlog.ll_host));
#endif
if ( (lseek (fd, offset, SEEK_SET) != offset)
|| (write_full(fd, &newlog, sizeof newlog) == -1)

8
lib/utmp.c
View File

@@ -262,25 +262,25 @@ static
utent->ut_type = USER_PROCESS;
#endif /* HAVE_STRUCT_UTMP_UT_TYPE */
utent->ut_pid = getpid ();
strncpy (utent->ut_line, line, sizeof (utent->ut_line) - 1);
strncpy(utent->ut_line, line, sizeof(utent->ut_line));
#ifdef HAVE_STRUCT_UTMP_UT_ID
if (NULL != ut) {
strncpy (utent->ut_id, ut->ut_id, sizeof (utent->ut_id));
} else {
/* XXX - assumes /dev/tty?? */
strncpy (utent->ut_id, line + 3, sizeof (utent->ut_id) - 1);
strncpy(utent->ut_id, line + 3, sizeof(utent->ut_id));
}
#endif /* HAVE_STRUCT_UTMP_UT_ID */
#ifdef HAVE_STRUCT_UTMP_UT_NAME
strncpy (utent->ut_name, name, sizeof (utent->ut_name));
#endif /* HAVE_STRUCT_UTMP_UT_NAME */
#ifdef HAVE_STRUCT_UTMP_UT_USER
strncpy (utent->ut_user, name, sizeof (utent->ut_user) - 1);
strncpy(utent->ut_user, name, sizeof(utent->ut_user));
#endif /* HAVE_STRUCT_UTMP_UT_USER */
if (NULL != hostname) {
struct addrinfo *info = NULL;
#ifdef HAVE_STRUCT_UTMP_UT_HOST
strncpy (utent->ut_host, hostname, sizeof (utent->ut_host) - 1);
strncpy(utent->ut_host, hostname, sizeof(utent->ut_host));
#endif /* HAVE_STRUCT_UTMP_UT_HOST */
#ifdef HAVE_STRUCT_UTMP_UT_SYSLEN
utent->ut_syslen = MIN (strlen (hostname),