[PATCH] ext4fs: Fix: Read outside partition error

[Tony Dinh]

Use lbaint_t for blknr to avoid overflow in ext4fs_read_file().

Background:

blknr (block number) used in ext4fs_read_file() could be increased to a
very large value and causes a wrap around at 32 bit signed integer max,
thus becomes negative. This results in an out-of-normal range for sector
number (during the assignment delayed_start = blknr) where delayed_start
sector is typed uint64 lbaint_t. This causes the "Read outside partition"
error.

This patch was tested on the Synology DS116 (Armada 385) board, and a
4TB Seagate HDD.

Signed-off-by: Tony Dinh <mibodhi at gmail.com>
---

 fs/ext4/ext4fs.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/ext4/ext4fs.c b/fs/ext4/ext4fs.c
index 1727da2dc6d..f10c622e62c 100644
--- a/fs/ext4/ext4fs.c
+++ b/fs/ext4/ext4fs.c
@@ -101,7 +101,7 @@ int ext4fs_read_file(struct ext2fs_node *node, loff_t pos,
 	blockcnt = lldiv(((len + pos) + blocksize - 1), blocksize);
 
 	for (i = lldiv(pos, blocksize); i < blockcnt; i++) {
-		long int blknr;
+		lbaint_t blknr;
 		int blockoff = pos - (blocksize * i);
 		int blockend = blocksize;
 		int skipfirst = 0;
-- 
2.39.5

base-commit: 421d4844591e967435fe0fcfa048ad45c3a48377
branch: master