ext4fs: Fix: Read outside partition error

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@gmail.com>

diff --git a/fs/ext4/ext4fs.c b/fs/ext4/ext4fs.c
index 1727da2..f10c622 100644 (file)
--- 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;