diff --git a/include/linux/printk.h b/include/linux/printk.h
index 4d5bf5726578c58b739a79a5f093e5f7c4a009a3..baa3f97d8ce87b4e63aceffa2fd9efeb8871c5e4 100644
--- a/include/linux/printk.h
+++ b/include/linux/printk.h
@@ -417,9 +417,9 @@ enum {
DUMP_PREFIX_ADDRESS,
DUMP_PREFIX_OFFSET
};
-extern void hex_dump_to_buffer(const void *buf, size_t len,
- int rowsize, int groupsize,
- char *linebuf, size_t linebuflen, bool ascii);
+extern int hex_dump_to_buffer(const void *buf, size_t len, int rowsize,
+ int groupsize, char *linebuf, size_t linebuflen,
+ bool ascii);
#ifdef CONFIG_PRINTK
extern void print_hex_dump(const char *level, const char *prefix_str,
int prefix_type, int rowsize, int groupsize,
diff --git a/lib/hexdump.c b/lib/hexdump.c
index 4af53f73c7ccd4306d99adc5d41d115505bb9e5b..7ea09699855d98db901737bb6cfad30f4b32149f 100644
--- a/lib/hexdump.c
+++ b/lib/hexdump.c
@@ -97,22 +97,26 @@ EXPORT_SYMBOL(bin2hex);
*
* example output buffer:
* 40 41 42 43 44 45 46 47 48 49 4a 4b 4c 4d 4e 4f @ABCDEFGHIJKLMNO
+ *
+ * Return:
+ * The amount of bytes placed in the buffer without terminating NUL. If the
+ * output was truncated, then the return value is the number of bytes
+ * (excluding the terminating NUL) which would have been written to the final
+ * string if enough space had been available.
*/
-void hex_dump_to_buffer(const void *buf, size_t len, int rowsize,
- int groupsize, char *linebuf, size_t linebuflen,
- bool ascii)
+int hex_dump_to_buffer(const void *buf, size_t len, int rowsize, int groupsize,
+ char *linebuf, size_t linebuflen, bool ascii)
{
const u8 *ptr = buf;
int ngroups;
u8 ch;
int j, lx = 0;
int ascii_column;
+ int ret;
if (rowsize != 16 && rowsize != 32)
rowsize = 16;
- if (!len)
- goto nil;
if (len > rowsize) /* limit to one line at a time */
len = rowsize;
if (!is_power_of_2(groupsize) || groupsize > 8)
@@ -122,27 +126,50 @@ void hex_dump_to_buffer(const void *buf, size_t len, int rowsize,
ngroups = len / groupsize;
ascii_column = rowsize * 2 + rowsize / groupsize + 1;
+
+ if (!linebuflen)
+ goto overflow1;
+
+ if (!len)
+ goto nil;
+
if (groupsize == 8) {
const u64 *ptr8 = buf;
- for (j = 0; j < ngroups; j++)
- lx += scnprintf(linebuf + lx, linebuflen - lx,
- "%s%16.16llx", j ? " " : "",
- (unsigned long long)*(ptr8 + j));
+ for (j = 0; j < ngroups; j++) {
+ ret = snprintf(linebuf + lx, linebuflen - lx,
+ "%s%16.16llx", j ? " " : "",
+ (unsigned long long)*(ptr8 + j));
+ if (ret >= linebuflen - lx)
+ goto overflow1;
+ lx += ret;
+ }
} else if (groupsize == 4) {
const u32 *ptr4 = buf;
- for (j = 0; j < ngroups; j++)
- lx += scnprintf(linebuf + lx, linebuflen - lx,
- "%s%8.8x", j ? " " : "", *(ptr4 + j));
+ for (j = 0; j < ngroups; j++) {
+ ret = snprintf(linebuf + lx, linebuflen - lx,
+ "%s%8.8x", j ? " " : "",
+ *(ptr4 + j));
+ if (ret >= linebuflen - lx)
+ goto overflow1;
+ lx += ret;
+ }
} else if (groupsize == 2) {
const u16 *ptr2 = buf;
- for (j = 0; j < ngroups; j++)
- lx += scnprintf(linebuf + lx, linebuflen - lx,
- "%s%4.4x", j ? " " : "", *(ptr2 + j));
+ for (j = 0; j < ngroups; j++) {
+ ret = snprintf(linebuf + lx, linebuflen - lx,
+ "%s%4.4x", j ? " " : "",
+ *(ptr2 + j));
+ if (ret >= linebuflen - lx)
+ goto overflow1;
+ lx += ret;
+ }
} else {
- for (j = 0; (j < len) && (lx + 3) <= linebuflen; j++) {
+ for (j = 0; j < len; j++) {
+ if (linebuflen < lx + 3)
+ goto overflow2;
ch = ptr[j];
linebuf[lx++] = hex_asc_hi(ch);
linebuf[lx++] = hex_asc_lo(ch);
@@ -154,14 +181,24 @@ void hex_dump_to_buffer(const void *buf, size_t len, int rowsize,
if (!ascii)
goto nil;
- while (lx < (linebuflen - 1) && lx < ascii_column)
+ while (lx < ascii_column) {
+ if (linebuflen < lx + 2)
+ goto overflow2;
linebuf[lx++] = ' ';
- for (j = 0; (j < len) && (lx + 2) < linebuflen; j++) {
+ }
+ for (j = 0; j < len; j++) {
+ if (linebuflen < lx + 2)
+ goto overflow2;
ch = ptr[j];
linebuf[lx++] = (isascii(ch) && isprint(ch)) ? ch : '.';
}
nil:
+ linebuf[lx] = '\0';
+ return lx;
+overflow2:
linebuf[lx++] = '\0';
+overflow1:
+ return ascii ? ascii_column + len : (groupsize * 2 + 1) * ngroups - 1;
}
EXPORT_SYMBOL(hex_dump_to_buffer);
diff --git a/lib/test-hexdump.c b/lib/test-hexdump.c
index 9d3bd1e9ae488a313a3d09a08864bf52b58da644..daf29a390a89d184dc05a485e38206a1f1e4a827 100644
--- a/lib/test-hexdump.c
+++ b/lib/test-hexdump.c
@@ -114,6 +114,45 @@ static void __init test_hexdump_set(int rowsize, bool ascii)
test_hexdump(len, rowsize, 1, ascii);
}
+static void __init test_hexdump_overflow(bool ascii)
+{
+ char buf[56];
+ const char *t = test_data_1_le[0];
+ size_t l = get_random_int() % sizeof(buf);
+ bool a;
+ int e, r;
+
+ memset(buf, ' ', sizeof(buf));
+
+ r = hex_dump_to_buffer(data_b, 1, 16, 1, buf, l, ascii);
+
+ if (ascii)
+ e = 50;
+ else
+ e = 2;
+ buf[e + 2] = '\0';
+
+ if (!l) {
+ a = r == e && buf[0] == ' ';
+ } else if (l < 3) {
+ a = r == e && buf[0] == '\0';
+ } else if (l < 4) {
+ a = r == e && !strcmp(buf, t);
+ } else if (ascii) {
+ if (l < 51)
+ a = r == e && buf[l - 1] == '\0' && buf[l - 2] == ' ';
+ else
+ a = r == e && buf[50] == '\0' && buf[49] == '.';
+ } else {
+ a = r == e && buf[e] == '\0';
+ }
+
+ if (!a) {
+ pr_err("Len: %zu rc: %u strlen: %zu\n", l, r, strlen(buf));
+ pr_err("Result: '%s'\n", buf);
+ }
+}
+
static int __init test_hexdump_init(void)
{
unsigned int i;
@@ -129,6 +168,12 @@ static int __init test_hexdump_init(void)
for (i = 0; i < 16; i++)
test_hexdump_set(rowsize, true);
+ for (i = 0; i < 16; i++)
+ test_hexdump_overflow(false);
+
+ for (i = 0; i < 16; i++)
+ test_hexdump_overflow(true);
+
return -EINVAL;
}
module_init(test_hexdump_init);