The patch titled
Subject: fat: add simple validation for directory inode
has been added to the -mm tree. Its filename is
fat-add-simple-validation-for-directory-inode.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/fat-add-simple-validation-for-directory-inode.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/fat-add-simple-validation-for-directory-inode.patch
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------------------------------------------------------
From: OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx>
Subject: fat: add simple validation for directory inode
This detects simple corruption cases of directory, and tries to avoid
further damage to user data.
And performance impact of this validation should be very low, or not
measurable.
Signed-off-by: OGAWA Hirofumi <hirofumi@xxxxxxxxxxxxxxxxxx>
Reported-by: Vegard Nossum <vegard.nossum@xxxxxxxxxx>
Tested-by: Vegard Nossum <vegard.nossum@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/fat/inode.c | 22 ++++++++++++++++++++++
1 file changed, 22 insertions(+)
diff -puN fs/fat/inode.c~fat-add-simple-validation-for-directory-inode fs/fat/inode.c
--- a/fs/fat/inode.c~fat-add-simple-validation-for-directory-inode
+++ a/fs/fat/inode.c
@@ -449,6 +449,24 @@ static int fat_calc_dir_size(struct inod
return 0;
}
+static int fat_validate_dir(struct inode *dir)
+{
+ struct super_block *sb = dir->i_sb;
+
+ if (dir->i_nlink < 2) {
+ /* Directory should have "."/".." entries at least. */
+ fat_fs_error(sb, "corrupted directory (invalid entries)");
+ return -EIO;
+ }
+ if (MSDOS_I(dir)->i_start == 0 ||
+ MSDOS_I(dir)->i_start == MSDOS_SB(sb)->root_cluster) {
+ /* Directory should point valid cluster. */
+ fat_fs_error(sb, "corrupted directory (invalid i_start)");
+ return -EIO;
+ }
+ return 0;
+}
+
/* doesn't deal with root inode */
int fat_fill_inode(struct inode *inode, struct msdos_dir_entry *de)
{
@@ -475,6 +493,10 @@ int fat_fill_inode(struct inode *inode,
MSDOS_I(inode)->mmu_private = inode->i_size;
set_nlink(inode, fat_subdirs(inode));
+
+ error = fat_validate_dir(inode);
+ if (error < 0)
+ return error;
} else { /* not a directory */
inode->i_generation |= 1;
inode->i_mode = fat_make_mode(sbi, de->attr,
_
Patches currently in -mm which might be from hirofumi@xxxxxxxxxxxxxxxxxx are
fat-add-simple-validation-for-directory-inode.patch
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