[PATCH v4 2/2] fs: semihosting: Fixup smh_flen against overflow

[Andrew Goodbody]

The sys calls SYS_FLEN was being used in a way that did ot allow for
file sizes > 2^31. Fixing this required changing the signature of the
function to allow file sizes up to 2^32 - 2 and also being able to
return errors that could be tested for.

This issue was found by Smatch.

Signed-off-by: Andrew Goodbody <andrew.goodbody at linaro.org>
---
 common/spl/spl_semihosting.c |  6 +++---
 fs/semihostingfs.c           | 14 ++++++++------
 include/semihosting.h        |  5 +++--
 lib/semihosting.c            |  6 ++++--
 4 files changed, 18 insertions(+), 13 deletions(-)

diff --git a/common/spl/spl_semihosting.c b/common/spl/spl_semihosting.c
index cff6f5351e265136b3effe483fd5d641fdd109f8..fb578a274d0d937b2ed5bd13e505bcefd4491799 100644
--- a/common/spl/spl_semihosting.c
+++ b/common/spl/spl_semihosting.c
@@ -28,7 +28,8 @@ static int spl_smh_load_image(struct spl_image_info *spl_image,
 {
 	const char *filename = CONFIG_SPL_FS_LOAD_PAYLOAD_NAME;
 	int ret;
-	long fd, len;
+	long fd;
+	size_t len;
 	struct spl_load_info load;
 
 	fd = smh_open(filename, MODE_READ | MODE_BINARY);
@@ -37,12 +38,11 @@ static int spl_smh_load_image(struct spl_image_info *spl_image,
 		return fd;
 	}
 
-	ret = smh_flen(fd);
+	ret = smh_flen(fd, &len);
 	if (ret < 0) {
 		log_debug("could not get length of image: %d\n", ret);
 		goto out;
 	}
-	len = ret;
 
 	spl_load_init(&load, smh_fit_read, &fd, 1);
 	ret = spl_load(spl_image, bootdev, &load, len, 0);
diff --git a/fs/semihostingfs.c b/fs/semihostingfs.c
index 15f58d578b65f7dbbadce19093546f5bdb46c0c3..6a4d0aaaf2fdaf8da154e59677839a5c7a4889e9 100644
--- a/fs/semihostingfs.c
+++ b/fs/semihostingfs.c
@@ -35,10 +35,10 @@ static int smh_fs_read_at(const char *filename, loff_t pos, void *buffer,
 		return ret;
 	}
 	if (!maxsize) {
-		size = smh_flen(fd);
+		ret = smh_flen(fd, &size);
 		if (ret < 0) {
 			smh_close(fd);
-			return size;
+			return ret;
 		}
 
 		maxsize = size;
@@ -79,17 +79,19 @@ static int smh_fs_write_at(const char *filename, loff_t pos, void *buffer,
 
 int smh_fs_size(const char *filename, loff_t *result)
 {
-	long fd, size;
+	long fd;
+	size_t size;
+	int ret;
 
 	fd = smh_open(filename, MODE_READ | MODE_BINARY);
 	if (fd < 0)
 		return fd;
 
-	size = smh_flen(fd);
+	ret = smh_flen(fd, &size);
 	smh_close(fd);
 
-	if (size < 0)
-		return size;
+	if (ret < 0)
+		return ret;
 
 	*result = size;
 	return 0;
diff --git a/include/semihosting.h b/include/semihosting.h
index 42832d86c711ff04e91b6b739c80629253f6d30a..60535199b9532ce16620aea3ca1ea741c5b73766 100644
--- a/include/semihosting.h
+++ b/include/semihosting.h
@@ -124,10 +124,11 @@ long smh_close(long fd);
 /**
  * smh_flen() - Get the length of a file
  * @fd: A file descriptor returned from smh_open()
+ * @size: Pointer which will be updated with length of file on success
  *
- * Return: The length of the file, in bytes, or a negative error on failure
+ * Return: 0 on success or negative error on failure
  */
-long smh_flen(long fd);
+int smh_flen(long fd, size_t *size);
 
 /**
  * smh_seek() - Seek to a position in a file
diff --git a/lib/semihosting.c b/lib/semihosting.c
index e49b16b0aa34ab04b6c8949a3e7cab539fdbef82..547a936e17f38204e840035a50f481e57d159592 100644
--- a/lib/semihosting.c
+++ b/lib/semihosting.c
@@ -154,7 +154,7 @@ long smh_close(long fd)
 	return 0;
 }
 
-long smh_flen(long fd)
+int smh_flen(long fd, size_t *size)
 {
 	long ret;
 
@@ -163,7 +163,9 @@ long smh_flen(long fd)
 	ret = smh_trap(SYSFLEN, &fd);
 	if (ret == -1)
 		return smh_errno();
-	return ret;
+
+	*size = (size_t)ret;
+	return 0;
 }
 
 long smh_seek(long fd, long pos)

-- 
2.47.3