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efivarfs: revert "fix memory leak in efivarfs_create()"

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[ Upstream commit ff04f3b6f2e27f8ae28a498416af2a8dd5072b43 ]

The memory leak addressed by commit fe5186cf12e3 is a false positive:
all allocations are recorded in a linked list, and freed when the
filesystem is unmounted. This leads to double frees, and as reported
by David, leads to crashes if SLUB is configured to self destruct when
double frees occur.

So drop the redundant kfree() again, and instead, mark the offending
pointer variable so the allocation is ignored by kmemleak.

Cc: Vamshi K Sthambamkadi <vamshi.k.sthambamkadi@gmail.com>
Fixes: fe5186cf12e3 ("efivarfs: fix memory leak in efivarfs_create()")
Reported-by: David Laight <David.Laight@aculab.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Ard Biesheuvel 2020-11-25 08:45:55 +01:00 committed by Greg Kroah-Hartman
parent abae897f28
commit 0d245cbd93
2 changed files with 2 additions and 1 deletions
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2
fs/efivarfs/inode.c
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@ -7,6 +7,7 @@
#include <linux/efi.h> #include <linux/efi.h>
#include <linux/fs.h> #include <linux/fs.h>
#include <linux/ctype.h> #include <linux/ctype.h>
#include <linux/kmemleak.h>
#include <linux/slab.h> #include <linux/slab.h>
#include <linux/uuid.h> #include <linux/uuid.h>
@ -103,6 +104,7 @@ static int efivarfs_create(struct inode *dir, struct dentry *dentry,
var->var.VariableName[i] = '\0'; var->var.VariableName[i] = '\0';
inode->i_private = var; inode->i_private = var;
kmemleak_ignore(var);
err = efivar_entry_add(var, &efivarfs_list); err = efivar_entry_add(var, &efivarfs_list);
if (err) if (err)

1
fs/efivarfs/super.c
View File

@ -21,7 +21,6 @@ LIST_HEAD(efivarfs_list);
static void efivarfs_evict_inode(struct inode *inode) static void efivarfs_evict_inode(struct inode *inode)
{ {
clear_inode(inode); clear_inode(inode);
kfree(inode->i_private);
} }
static const struct super_operations efivarfs_ops = { static const struct super_operations efivarfs_ops = {