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hostfs: fix memory handling in follow_link()

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[ Upstream commit 7f6c411c9b50cfab41cc798e003eff27608c7016 ]

1) argument should not be freed in any case - the caller already has
it as ->s_fs_info (and uses it a lot afterwards)
2) allocate readlink buffer with kmalloc() - the caller has no way
to tell if it's got that (on absolute symlink) or a result of
kasprintf().  Sure, for SLAB and SLUB kfree() works on results of
kmem_cache_alloc(), but that's not documented anywhere, might change
in the future *and* is already not true for SLOB.

Fixes: 52b209f7b8 ("get rid of hostfs_read_inode()")
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Al Viro 2021-03-25 14:12:34 -04:00 committed by Greg Kroah-Hartman
parent 613f35568a
commit e472f6814c
1 changed files with 3 additions and 4 deletions
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7
fs/hostfs/hostfs_kern.c
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@ -142,7 +142,7 @@ static char *follow_link(char *link)
char *name, *resolved, *end;
int n;
name = __getname();
name = kmalloc(PATH_MAX, GFP_KERNEL);
if (!name) {
n = -ENOMEM;
goto out_free;
@ -171,12 +171,11 @@ static char *follow_link(char *link)
goto out_free;
}
__putname(name);
kfree(link);
kfree(name);
return resolved;
out_free:
__putname(name);
kfree(name);
return ERR_PTR(n);
}