[PATCH] f2fs: add a condition to detect overflow in f2fs_ioc_gc_range()

[PATCH] f2fs: add a condition to detect overflow in f2fs_ioc_gc_range()

[Sahitya Tummala]

end = range.start + range.len;

If the range.start/range.len is a very large value, then end can overflow
in this operation. It results into a crash in get_valid_blocks() when
accessing the invalid range.start segno.

This issue is reported in ioctl fuzz testing.

Signed-off-by: Sahitya Tummala <stummala@codeaurora.org>
---
 fs/f2fs/file.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/fs/f2fs/file.c b/fs/f2fs/file.c
index 5474aaa..c2b4767 100644
--- a/fs/f2fs/file.c
+++ b/fs/f2fs/file.c
@@ -2123,9 +2123,8 @@ static int f2fs_ioc_gc_range(struct file *filp, unsigned long arg)
 		return -EROFS;
 
 	end = range.start + range.len;
-	if (range.start < MAIN_BLKADDR(sbi) || end >= MAX_BLKADDR(sbi)) {
+	if (end < range.start || range.start < MAIN_BLKADDR(sbi) || end >= MAX_BLKADDR(sbi))
 		return -EINVAL;
-	}
 
 	ret = mnt_want_write_file(filp);
 	if (ret)
-- 
Qualcomm India Private Limited, on behalf of Qualcomm Innovation Center, Inc.
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project.

Re: [PATCH] f2fs: add a condition to detect overflow in f2fs_ioc_gc_range()

[Chao Yu]

On 2019/9/17 12:49, Sahitya Tummala wrote:
> end = range.start + range.len;
> 
> If the range.start/range.len is a very large value, then end can overflow
> in this operation. It results into a crash in get_valid_blocks() when
> accessing the invalid range.start segno.
> 
> This issue is reported in ioctl fuzz testing.
> 
> Signed-off-by: Sahitya Tummala <stummala@codeaurora.org>

Reviewed-by: Chao Yu <yuchao0@huawei.com>

Thanks,