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Chen Zhongjin 8bc7775422 configfs: fix possible memory leak in configfs_create_dir() 
[ Upstream commit c65234b283 ]

kmemleak reported memory leaks in configfs_create_dir():

unreferenced object 0xffff888009f6af00 (size 192):
  comm "modprobe", pid 3777, jiffies 4295537735 (age 233.784s)
  backtrace:
    kmem_cache_alloc (mm/slub.c:3250 mm/slub.c:3256 mm/slub.c:3263 mm/slub.c:3273)
    new_fragment (./include/linux/slab.h:600 fs/configfs/dir.c:163)
    configfs_register_subsystem (fs/configfs/dir.c:1857)
    basic_write (drivers/hwtracing/stm/p_basic.c:14) stm_p_basic
    do_one_initcall (init/main.c:1296)
    do_init_module (kernel/module/main.c:2455)
    ...

unreferenced object 0xffff888003ba7180 (size 96):
  comm "modprobe", pid 3777, jiffies 4295537735 (age 233.784s)
  backtrace:
    kmem_cache_alloc (mm/slub.c:3250 mm/slub.c:3256 mm/slub.c:3263 mm/slub.c:3273)
    configfs_new_dirent (./include/linux/slab.h:723 fs/configfs/dir.c:194)
    configfs_make_dirent (fs/configfs/dir.c:248)
    configfs_create_dir (fs/configfs/dir.c:296)
    configfs_attach_group.isra.28 (fs/configfs/dir.c:816 fs/configfs/dir.c:852)
    configfs_register_subsystem (fs/configfs/dir.c:1881)
    basic_write (drivers/hwtracing/stm/p_basic.c:14) stm_p_basic
    do_one_initcall (init/main.c:1296)
    do_init_module (kernel/module/main.c:2455)
    ...

This is because the refcount is not correct in configfs_make_dirent().
For normal stage, the refcount is changing as:

configfs_register_subsystem()
  configfs_create_dir()
    configfs_make_dirent()
      configfs_new_dirent() # set s_count = 1
      dentry->d_fsdata = configfs_get(sd); # s_count = 2
...
configfs_unregister_subsystem()
  configfs_remove_dir()
    remove_dir()
      configfs_remove_dirent() # s_count = 1
    dput() ...
      *dentry_unlink_inode()*
        configfs_d_iput() # s_count = 0, release

However, if we failed in configfs_create():

configfs_register_subsystem()
  configfs_create_dir()
    configfs_make_dirent() # s_count = 2
    ...
    configfs_create() # fail
    ->out_remove:
    configfs_remove_dirent(dentry)
      configfs_put(sd) # s_count = 1
      return PTR_ERR(inode);

There is no inode in the error path, so the configfs_d_iput() is lost
and makes sd and fragment memory leaked.

To fix this, when we failed in configfs_create(), manually call
configfs_put(sd) to keep the refcount correct.

Fixes: 7063fbf226 ("[PATCH] configfs: User-driven configuration filesystem")
Signed-off-by: Chen Zhongjin <chenzhongjin@huawei.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2022-12-31 13:26:08 +01:00
arch x86/boot: Skip realmode init code when running as Xen PV guest 2022-12-31 13:26:03 +01:00
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Documentation dt-bindings: clock: Add resets for LPASS audio clock controller for SC7280 2022-12-31 13:26:07 +01:00
drivers clk: qcom: clk-krait: fix wrong div2 functions 2022-12-31 13:26:08 +01:00
fs configfs: fix possible memory leak in configfs_create_dir() 2022-12-31 13:26:08 +01:00
include dt-bindings: clock: Add support for external MCLKs for LPASS on SC7280 2022-12-31 13:26:07 +01:00
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README 

Linux kernel
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There are several guides for kernel developers and users. These guides can
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In order to build the documentation, use ``make htmldocs`` or
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There are various text files in the Documentation/ subdirectory,
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Please read the Documentation/process/changes.rst file, as it contains the
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