Do not read past the end of fmt_desc[]

Callers of parse_format() pass a size in bytes while the parse_format()
function itself expects a number of elements. Fix this by making the
fmt_desc[] array NULL-terminated. This patch fixes the following Coverity
complaint:

CID 300986 (#1 of 1): Out-of-bounds access (OVERRUN)
overrun-buffer-arg: Overrunning array fmt_desc of 1 24-byte elements by
passing it to a function which accesses it at element index 23 (byte
offset 575) using argument 24U.

Cc: Roman Pen <r.peniaev@gmail.com>
Fixes: 634bd210c17a ("lib/pattern: add set of functions to parse combined pattern input")
Signed-off-by: Bart Van Assche <bvanassche@acm.org>

3 files changed, 7 insertions, 12 deletions

diff --git a/lib/pattern.c b/lib/pattern.c
index 04d30657..680a12be 100644
--- a/lib/pattern.c
+++ b/lib/pattern.c
@@ -205,7 +205,6 @@ static const char *parse_number(const char *beg, char *out,
  * @parsed - number of bytes which were already parsed so far
  * @out_len - length of the output buffer
  * @fmt_desc - format descriptor array, what we expect to find
- * @fmt_desc_sz - size of the format descriptor array
  * @fmt - format array, the output
  * @fmt_sz - size of format array
  *
@@ -223,19 +222,18 @@ static const char *parse_number(const char *beg, char *out,
 static const char *parse_format(const char *in, char *out, unsigned int parsed,
 				unsigned int out_len, unsigned int *filled,
 				const struct pattern_fmt_desc *fmt_desc,
-				unsigned int fmt_desc_sz,
 				struct pattern_fmt *fmt, unsigned int fmt_sz)
 {
 	int i;
 	struct pattern_fmt *f = NULL;
 	unsigned int len = 0;
 
-	if (!out_len || !fmt_desc || !fmt_desc_sz || !fmt || !fmt_sz)
+	if (!out_len || !fmt_desc || !fmt || !fmt_sz)
 		return NULL;
 
 	assert(*in == '%');
 
-	for (i = 0; i < fmt_desc_sz; i++) {
+	for (i = 0; fmt_desc[i].fmt; i++) {
 		const struct pattern_fmt_desc *desc;
 
 		desc = &fmt_desc[i];
@@ -267,7 +265,6 @@ static const char *parse_format(const char *in, char *out, unsigned int parsed,
  * @out - output buffer where parsed result will be put
  * @out_len - lengths of the output buffer
  * @fmt_desc - array of pattern format descriptors [input]
- * @fmt_desc_sz - size of the format descriptor array
  * @fmt - array of pattern formats [output]
  * @fmt_sz - pointer where the size of pattern formats array stored [input],
  *           after successfull parsing this pointer will contain the number
@@ -311,7 +308,6 @@ static const char *parse_format(const char *in, char *out, unsigned int parsed,
 int parse_and_fill_pattern(const char *in, unsigned int in_len,
 			   char *out, unsigned int out_len,
 			   const struct pattern_fmt_desc *fmt_desc,
-			   unsigned int fmt_desc_sz,
 			   struct pattern_fmt *fmt,
 			   unsigned int *fmt_sz_out)
 {
@@ -340,8 +336,7 @@ int parse_and_fill_pattern(const char *in, unsigned int in_len,
 			break;
 		case '%':
 			end = parse_format(beg, out, out - out_beg, out_len,
-					   &filled, fmt_desc, fmt_desc_sz,
-					   fmt, fmt_rem);
+					   &filled, fmt_desc, fmt, fmt_rem);
 			parsed_fmt = 1;
 			break;
 		default:
diff --git a/lib/pattern.h b/lib/pattern.h
index 2d655ad0..a6d9d6b4 100644
--- a/lib/pattern.h
+++ b/lib/pattern.h
@@ -24,7 +24,6 @@ struct pattern_fmt {
 int parse_and_fill_pattern(const char *in, unsigned int in_len,
 			   char *out, unsigned int out_len,
 			   const struct pattern_fmt_desc *fmt_desc,
-			   unsigned int fmt_desc_sz,
 			   struct pattern_fmt *fmt,
 			   unsigned int *fmt_sz_out);
 
diff --git a/options.c b/options.c
index bb450fff..85a0f490 100644
--- a/options.c
+++ b/options.c
@@ -24,7 +24,8 @@ static const struct pattern_fmt_desc fmt_desc[] = {
 		.fmt   = "%o",
 		.len   = FIELD_SIZE(struct io_u *, offset),
 		.paste = paste_blockoff
-	}
+	},
+	{ }
 };
 
 /*
@@ -1339,7 +1340,7 @@ static int str_buffer_pattern_cb(void *data, const char *input)
 
 	/* FIXME: for now buffer pattern does not support formats */
 	ret = parse_and_fill_pattern(input, strlen(input), td->o.buffer_pattern,
-				     MAX_PATTERN_SIZE, NULL, 0, NULL, NULL);
+				     MAX_PATTERN_SIZE, NULL, NULL, NULL);
 	if (ret < 0)
 		return 1;
 
@@ -1388,7 +1389,7 @@ static int str_verify_pattern_cb(void *data, const char *input)
 
 	td->o.verify_fmt_sz = ARRAY_SIZE(td->o.verify_fmt);
 	ret = parse_and_fill_pattern(input, strlen(input), td->o.verify_pattern,
-				     MAX_PATTERN_SIZE, fmt_desc, sizeof(fmt_desc),
+				     MAX_PATTERN_SIZE, fmt_desc,
 				     td->o.verify_fmt, &td->o.verify_fmt_sz);
 	if (ret < 0)
 		return 1;