[PATCH] f2fs: file: add checks to f2fs_ioc_flush_device()

[Roman Smirnov]

If invalid data is copied from user space and if GET_SEGNO()
returns NULL_SEGNO an overflow is possible.

Add checks for invalid values.

Found by Linux Verification Center (linuxtesting.org) with Svace.

Signed-off-by: Roman Smirnov <r.smirnov@xxxxxx>
---
 fs/f2fs/file.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index 168f08507004..1b9c4fee9db1 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -3093,6 +3093,9 @@ static int f2fs_ioc_flush_device(struct file *filp, unsigned long arg)
 		start_segno = dev_start_segno;
 	end_segno = min(start_segno + range.segments, dev_end_segno);
 
+	if (start_segno > F2FS_MAX_SEGMENT - range.segments || end_segno == NULL_SEGNO)
+		return -EINVAL;
+
 	while (start_segno < end_segno) {
 		if (!f2fs_down_write_trylock(&sbi->gc_lock)) {
 			ret = -EBUSY;
-- 
2.43.0