Re: [PATCH 4/5] fs: efs: fix possible memory leak

From: Al Viro
Date: Tue Feb 17 2015 - 14:31:10 EST

On Thu, Feb 12, 2015 at 02:32:21PM +0530, Sudip Mukherjee wrote:
> we are allocating memory for struct efs_sb_info, but afterwards when
> we are returning with error we are not releasing the memory.

The hell we are not - unlike ->put_super(), ->kill_sb() is *always*
called, even when fill_super() fails halfway through. Exactly because
it makes for simpler cleanup requirements on failure exits in said
fill_super(). And we have
static void efs_kill_sb(struct super_block *s)
struct efs_sb_info *sbi = SUPER_INFO(s);
for ->kill_sb() there, so sbi will *not* leak.

NAK. This patch not only complicates efs_fill_super() for no good reason,
it ends up with double kfree() on those failure exits - ->s_fs_info is
left pointing to freed memory and efs_kill_sb() does kfree() again.
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