On Fri, Mar 11, 2016 at 11:38:53PM +0800, Eryu Guan wrote:
> ext4_reserve_inode_write() in ext4_mark_inode_dirty() could fail on
> error (e.g. EIO) and iloc.bh can be NULL in this case. But the error is
> ignored in the following "if" condition and ext4_expand_extra_isize()
> might be called with NULL iloc.bh set, which triggers NULL pointer
> dereference.
Nice catch! I'm going fix this slightly differently (although I'll
keep your description). The patch is a wee bit bigger, but the end
result is simpler to read.
Thanks,
- Ted
diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
index ce2c4c6..b41432e 100644
--- a/fs/ext4/inode.c
+++ b/fs/ext4/inode.c
@@ -5312,6 +5312,8 @@ int ext4_mark_inode_dirty(handle_t *handle, struct inode *inode)
might_sleep();
trace_ext4_mark_inode_dirty(inode, _RET_IP_);
err = ext4_reserve_inode_write(handle, inode, &iloc);
+ if (err)
+ return err;
if (ext4_handle_valid(handle) &&
EXT4_I(inode)->i_extra_isize < sbi->s_want_extra_isize &&
!ext4_test_inode_state(inode, EXT4_STATE_NO_EXPAND)) {
@@ -5342,9 +5344,7 @@ int ext4_mark_inode_dirty(handle_t *handle, struct inode *inode)
}
}
}
- if (!err)
- err = ext4_mark_iloc_dirty(handle, inode, &iloc);
- return err;
+ return ext4_mark_iloc_dirty(handle, inode, &iloc);
}
/*
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