From: =?UTF-8?q?Daniel=20P=2E=20Berrang=C3=A9?= Date: Wed, 1 May 2019 15:46:46 +0100 Subject: linux-user: avoid string truncation warnings in uname field copying MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit In file included from /usr/include/string.h:494, from include/qemu/osdep.h:101, from linux-user/uname.c:20: In function ‘strncpy’, inlined from ‘sys_uname’ at linux-user/uname.c:94:3: /usr/include/bits/string_fortified.h:106:10: warning: ‘__builtin_strncpy’ output may be truncated copying 64 bytes from a string of length 64 [-Wstringop-truncation] 106 | return __builtin___strncpy_chk (__dest, __src, __len, __bos (__dest)); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ We don't care where the NUL terminator in the original uname field was. It suffices to copy the entire original field and simply force a NUL terminator at the end of the new field. Signed-off-by: Daniel P. Berrangé Reviewed-by: Philippe Mathieu-Daudé Message-Id: <20190501144646.4851-1-berrange@redhat.com> Signed-off-by: Laurent Vivier [BR: Played with indent to avoid error from checkpatch.pl] (cherry picked from commit b2acfb55962bc8caeaa50a5158da2f701f2c1f7c) Signed-off-by: Bruce Rogers --- linux-user/uname.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/linux-user/uname.c b/linux-user/uname.c index 313b79dbad..0c6ddf2ad9 100644 --- a/linux-user/uname.c +++ b/linux-user/uname.c @@ -72,9 +72,8 @@ const char *cpu_to_uname_machine(void *cpu_env) #define COPY_UTSNAME_FIELD(dest, src) \ do { \ - /* __NEW_UTS_LEN doesn't include terminating null */ \ - (void) strncpy((dest), (src), __NEW_UTS_LEN); \ - (dest)[__NEW_UTS_LEN] = '\0'; \ + memcpy((dest), (src), MIN(sizeof(src), sizeof(dest))); \ + (dest)[sizeof(dest) - 1] = '\0'; \ } while (0) int sys_uname(struct new_utsname *buf)