From 4bae615022cb5a5da79ccda83cc6c9ba9f2d479c Mon Sep 17 00:00:00 2001 From: Joseph Myers Date: Wed, 22 Nov 2017 18:44:23 +0000 Subject: [PATCH] Avoid use of strlen in getlogin_r (bug 22447). Building glibc with current mainline GCC fails, among other reasons, because of an error for use of strlen on the nonstring ut_user field. This patch changes the problem code in getlogin_r to use __strnlen instead. It also needs to set the trailing NUL byte of the result explicitly, because of the case where ut_user does not have such a trailing NUL byte (but the result should always have one). Tested for x86_64. Also tested that, in conjunction with , it fixes the build for arm with mainline GCC. [BZ #22447] * sysdeps/unix/getlogin_r.c (__getlogin_r): Use __strnlen not strlen to compute length of ut_user and set trailing NUL byte of result explicitly. --- ChangeLog | 7 +++++++ sysdeps/unix/getlogin_r.c | 5 +++-- 2 files changed, 10 insertions(+), 2 deletions(-) diff --git a/ChangeLog b/ChangeLog index 64a8d9c8ea..013d1e47e5 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,10 @@ +2017-11-22 Joseph Myers + + [BZ #22447] + * sysdeps/unix/getlogin_r.c (__getlogin_r): Use __strnlen not + strlen to compute length of ut_user and set trailing NUL byte of + result explicitly. + 2017-11-21 Mike FABIAN [BZ #15537] diff --git a/sysdeps/unix/getlogin_r.c b/sysdeps/unix/getlogin_r.c index 4a6a40eeb2..ad8e9111f6 100644 --- a/sysdeps/unix/getlogin_r.c +++ b/sysdeps/unix/getlogin_r.c @@ -80,7 +80,7 @@ __getlogin_r (char *name, size_t name_len) if (result == 0) { - size_t needed = strlen (ut->ut_user) + 1; + size_t needed = __strnlen (ut->ut_user, UT_NAMESIZE) + 1; if (needed > name_len) { @@ -89,7 +89,8 @@ __getlogin_r (char *name, size_t name_len) } else { - memcpy (name, ut->ut_user, needed); + memcpy (name, ut->ut_user, needed - 1); + name[needed - 1] = 0; result = 0; } } -- 2.11.4.GIT