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Subject[PATCH] protect ext3 ioctl modifying append_only, immutable, etc. with i_mutex
	All modifications of ->i_flags in inodes that might be visible to
somebody else must be under ->i_mutex. That patch fixes ext3 ioctl()
setting S_APPEND and friends.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

---
fs/ext3/ioctl.c | 18 ++++++++++++++----
1 files changed, 14 insertions(+), 4 deletions(-)
48ef5cddd158b0bbce7b646a16ba9ce3c599b0f1
diff --git a/fs/ext3/ioctl.c b/fs/ext3/ioctl.c
index aaf1da1..8c22aa9 100644
--- a/fs/ext3/ioctl.c
+++ b/fs/ext3/ioctl.c
@@ -48,6 +48,7 @@ int ext3_ioctl (struct inode * inode, st
if (!S_ISDIR(inode->i_mode))
flags &= ~EXT3_DIRSYNC_FL;

+ mutex_lock(&inode->i_mutex);
oldflags = ei->i_flags;

/* The JOURNAL_DATA flag is modifiable only by root */
@@ -60,8 +61,10 @@ int ext3_ioctl (struct inode * inode, st
* This test looks nicer. Thanks to Pauline Middelink
*/
if ((flags ^ oldflags) & (EXT3_APPEND_FL | EXT3_IMMUTABLE_FL)) {
- if (!capable(CAP_LINUX_IMMUTABLE))
+ if (!capable(CAP_LINUX_IMMUTABLE)) {
+ mutex_unlock(&inode->i_mutex);
return -EPERM;
+ }
}

/*
@@ -69,14 +72,18 @@ int ext3_ioctl (struct inode * inode, st
* the relevant capability.
*/
if ((jflag ^ oldflags) & (EXT3_JOURNAL_DATA_FL)) {
- if (!capable(CAP_SYS_RESOURCE))
+ if (!capable(CAP_SYS_RESOURCE)) {
+ mutex_unlock(&inode->i_mutex);
return -EPERM;
+ }
}


handle = ext3_journal_start(inode, 1);
- if (IS_ERR(handle))
+ if (IS_ERR(handle)) {
+ mutex_unlock(&inode->i_mutex);
return PTR_ERR(handle);
+ }
if (IS_SYNC(inode))
handle->h_sync = 1;
err = ext3_reserve_inode_write(handle, inode, &iloc);
@@ -93,11 +100,14 @@ int ext3_ioctl (struct inode * inode, st
err = ext3_mark_iloc_dirty(handle, inode, &iloc);
flags_err:
ext3_journal_stop(handle);
- if (err)
+ if (err) {
+ mutex_unlock(&inode->i_mutex);
return err;
+ }

if ((jflag ^ oldflags) & (EXT3_JOURNAL_DATA_FL))
err = ext3_change_inode_journal_flag(inode, jflag);
+ mutex_unlock(&inode->i_mutex);
return err;
}
case EXT3_IOC_GETVERSION:
--
1.3.0.g0080f
-
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