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ext4: fix kernel oops caused by spurious casefold flag

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If an directory has the a casefold flag set without the casefold
feature set, s_encoding will not be initialized, and this will cause
the kernel to dereference a NULL pointer.  In addition to adding
checks to avoid these kernel oops, attempts to load inodes with the
casefold flag when the casefold feature is not enable will cause the
file system to be declared corrupted.

Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This commit is contained in:
Theodore Ts'o
2019-09-03 01:43:17 -04:00
parent 9ba55543fc
commit 6456ca6520
4 changed files with 10 additions and 6 deletions
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4
fs/ext4/namei.c
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@@ -1312,7 +1312,7 @@ void ext4_fname_setup_ci_filename(struct inode *dir, const struct qstr *iname,
{
int len;
if (!IS_CASEFOLDED(dir)) {
if (!IS_CASEFOLDED(dir) || !EXT4_SB(dir->i_sb)->s_encoding) {
cf_name->name = NULL;
return;
}
@@ -2183,7 +2183,7 @@ static int ext4_add_entry(handle_t *handle, struct dentry *dentry,
#ifdef CONFIG_UNICODE
if (ext4_has_strict_mode(sbi) && IS_CASEFOLDED(dir) &&
utf8_validate(sbi->s_encoding, &dentry->d_name))
sbi->s_encoding && utf8_validate(sbi->s_encoding, &dentry->d_name))
return -EINVAL;
#endif