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[Qemu-devel] [PATCH v2 2/5] linux-user: avoid string truncation warnings
From: |
Daniel P . Berrangé |
Subject: |
[Qemu-devel] [PATCH v2 2/5] linux-user: avoid string truncation warnings in elf field copying |
Date: |
Fri, 12 Apr 2019 13:16:23 +0100 |
In file included from /usr/include/string.h:494,
from include/qemu/osdep.h:101,
from linux-user/elfload.c:2:
In function ‘strncpy’,
inlined from ‘fill_psinfo’ at linux-user/elfload.c:3208:12,
inlined from ‘fill_note_info’ at linux-user/elfload.c:3390:5,
inlined from ‘elf_core_dump’ at linux-user/elfload.c:3539:9:
/usr/include/bits/string_fortified.h:106:10: warning: ‘__builtin_strncpy’
specified bound 16 equals destination size [-Wstringop-truncation]
106 | return __builtin___strncpy_chk (__dest, __src, __len, __bos (__dest));
| ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
We don't require the field to be NUL terminated, so can just
copy the lower of the string length and the target field size
using memcpy.
Signed-off-by: Daniel P. Berrangé <address@hidden>
---
linux-user/elfload.c | 10 ++++------
1 file changed, 4 insertions(+), 6 deletions(-)
diff --git a/linux-user/elfload.c b/linux-user/elfload.c
index c1a26021f8..caa060f7b7 100644
--- a/linux-user/elfload.c
+++ b/linux-user/elfload.c
@@ -3180,6 +3180,7 @@ static int fill_psinfo(struct target_elf_prpsinfo
*psinfo, const TaskState *ts)
{
char *base_filename;
unsigned int i, len;
+ size_t pathlen;
(void) memset(psinfo, 0, sizeof (*psinfo));
@@ -3201,12 +3202,9 @@ static int fill_psinfo(struct target_elf_prpsinfo
*psinfo, const TaskState *ts)
psinfo->pr_gid = getgid();
base_filename = g_path_get_basename(ts->bprm->filename);
- /*
- * Using strncpy here is fine: at max-length,
- * this field is not NUL-terminated.
- */
- (void) strncpy(psinfo->pr_fname, base_filename,
- sizeof(psinfo->pr_fname));
+ pathlen = strlen(base_filename) + 1;
+ pathlen = MIN(pathlen, sizeof(psinfo->pr_fname));
+ memcpy(psinfo->pr_fname, base_filename, pathlen);
g_free(base_filename);
bswap_psinfo(psinfo);
--
2.20.1