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ANDROID: sdcardfs: fix potential crash when reserved_mb is not zero

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sdcardfs_mkdir() calls check_min_free_space(). When reserved_mb is not zero, a negative dentry will be passed to
ext4_statfs() at last and ext4_statfs() will crash. The parent dentry is positive. So we use the parent dentry to
check free space.

Change-Id: I80ab9623fe59ba911f4cc9f0e029a1c6f7ee421b
Signed-off-by: Lianjun Huang <huanglianjun@vivo.com>
This commit is contained in:
Lianjun Huang
2018-06-16 22:59:46 +08:00
parent a4230beab3
commit e1815b3eba
1 changed files with 5 additions and 1 deletions
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6
fs/sdcardfs/inode.c
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@@ -270,6 +270,7 @@ static int sdcardfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode
struct dentry *lower_dentry;
struct vfsmount *lower_mnt;
struct dentry *lower_parent_dentry = NULL;
struct dentry *parent_dentry = NULL;
struct path lower_path;
struct sdcardfs_sb_info *sbi = SDCARDFS_SB(dentry->d_sb);
const struct cred *saved_cred = NULL;
@@ -289,11 +290,14 @@ static int sdcardfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode
OVERRIDE_CRED(SDCARDFS_SB(dir->i_sb), saved_cred, SDCARDFS_I(dir));
/* check disk space */
if (!check_min_free_space(dentry, 0, 1)) {
parent_dentry = dget_parent(dentry);
if (!check_min_free_space(parent_dentry, 0, 1)) {
pr_err("sdcardfs: No minimum free space.\n");
err = -ENOSPC;
dput(parent_dentry);
goto out_revert;
}
dput(parent_dentry);
/* the lower_dentry is negative here */
sdcardfs_get_lower_path(dentry, &lower_path);