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authorSteven <sluong@cisco.com>2019-01-07 20:32:01 -0800
committerDave Barach <openvpp@barachs.net>2019-01-10 22:18:40 +0000
commitf09179f91aea0ca0b427a5097c0932dc64589fe0 (patch)
tree095df46689f5e66e766413366fcef1363e9dafef
parent339bc6b51dd1ea7d783b211c485881ccb495fd0d (diff)
strncpy_s_inline copies more bytes than necessary
Given n equals to the maximum number of bytes to copy from src in the API, or the rough estimate strlen of src, strncpy_s_inline should not copy more than the number of bytes, computed by strlen(src), to dst if n is greater than strlen(src). The number of bytes to copy is computed by strnlen(src,n), not n. Change-Id: I088b46125d9776962750e121f1fbf441952efc2b Signed-off-by: Steven <sluong@cisco.com>
-rw-r--r--src/plugins/unittest/string_test.c11
-rw-r--r--src/vppinfra/string.h5
2 files changed, 13 insertions, 3 deletions
diff --git a/src/plugins/unittest/string_test.c b/src/plugins/unittest/string_test.c
index 0d41bb27918..41b4c61dff4 100644
--- a/src/plugins/unittest/string_test.c
+++ b/src/plugins/unittest/string_test.c
@@ -628,7 +628,7 @@ test_strncpy_s (vlib_main_t * vm, unformat_input_t * input)
{
char src[] = "Those who dare to fail miserably can achieve greatly.";
char dst[100], old_dst[100];
- int indicator;
+ int indicator, i;
size_t s1size = sizeof (dst); // including null
errno_t err;
@@ -658,6 +658,10 @@ test_strncpy_s (vlib_main_t * vm, unformat_input_t * input)
return -1;
/* n > string len of src */
+ err = clib_memset (dst, 1, sizeof (dst));
+ if (err != EOK)
+ return -1;
+
err = strncpy_s (dst, s1size, src, clib_strnlen (src, sizeof (src)) + 10);
if (err != EOK)
return -1;
@@ -667,6 +671,11 @@ test_strncpy_s (vlib_main_t * vm, unformat_input_t * input)
if (indicator != 0)
return -1;
+ /* Make sure bytes after strlen(dst) is untouched */
+ for (i = 1 + clib_strnlen (dst, sizeof (dst)); i < sizeof (dst); i++)
+ if (dst[i] != 1)
+ return -1;
+
/* truncation, n >= dmax */
err = strncpy_s (dst, clib_strnlen (src, sizeof (src)), src,
clib_strnlen (src, sizeof (src)));
diff --git a/src/vppinfra/string.h b/src/vppinfra/string.h
index d5686704c22..42f7890f3d0 100644
--- a/src/vppinfra/string.h
+++ b/src/vppinfra/string.h
@@ -103,7 +103,7 @@ void clib_memswap (void *_a, void *_b, uword bytes);
* In order to provide smooth mapping from unsafe string API to the clib string
* macro, we often have to improvise s1max and s2max due to the additional
* arguments are required for implementing the safe API. This macro is used
- * to provide the s1max/s2max. It is not perfect becuase the actual
+ * to provide the s1max/s2max. It is not perfect because the actual
* s1max/s2max may be greater than 4k and the mapping from the unsafe API to
* the macro would cause a regression. However, it is not terribly likely.
* So I bet against the odds.
@@ -1025,7 +1025,8 @@ strncpy_s_inline (char *__restrict__ dest, rsize_t dmax,
}
}
else
- m = n;
+ /* cap the copy to strlen(src) in case n > strlen(src) */
+ m = clib_strnlen (src, n);
/* Check for src/dst overlap, which is not allowed */
low = (uword) (src < dest ? src : dest);